Volcanic activity, declining ocean oxygen triggered mass extinction of ancient organisms

June 12, 2018

Postdoctoral Fellow Theodore Them (left, holding an extinct fossil sample) and Assistant Professor Jeremy Owens (right, holding a rock core sample). The researchers used the samples to study the global record of oxygenation. Credit: Stephen Bilenky

Global climate change, fueled by skyrocketing levels of atmospheric carbon dioxide, is siphoning oxygen from today’s oceans at an alarming pace — so fast that scientists aren’t entirely sure how the planet will respond.

Their only hint? Look to the past.

In a study to be published this week in the journal Proceedings of the National Academy of Sciences, researchers from Florida State University did just that — and what they found brings into stark relief the disastrous effects a deoxygenated ocean could have on marine life.

Millions of years ago, scientists discovered, powerful volcanoes pumped Earth’s atmosphere full of carbon dioxide, draining the oceans of oxygen and driving a mass extinction of marine organisms.

“We want to understand how volcanism, which can be related to modern anthropogenic carbon dioxide release, manifests itself in ocean chemistry and extinction events,” said study co-author Jeremy Owens, an assistant professor in FSU’s Department of Earth, Ocean and Atmospheric Science. “Could this be a precursor to what we’re seeing today with oxygen loss in our oceans? Will we experience something as catastrophic as this mass extinction event?”

For this study, an international team of scientists set out to better understand today’s oxygen-deprived oceans by investigating the Toarcian Oceanic Anoxic Event (T-OAE), an interval of global oceanic deoxygenation characterized by a mass extinction of marine organisms that occurred in the Early Jurassic Period.

“We wanted to reconstruct Early Jurassic ocean oxygen levels to better understand the mass extinction and the T-OAE,” said Theodore Them, a postdoctoral researcher at FSU who led the study. “We used to think of ocean temperature and acidification as a one-two punch, but more recently we’ve learned this third variable, oxygen change, is equally important.”

By analyzing the thallium isotope composition of ancient rocks from North America and Europe, the team found that ocean oxygen began to deplete well before the defined time interval traditionally ascribed to the T-OAE.

That initial deoxygenation, researchers say, was precipitated by massive episodes of volcanic activity — a process not altogether unlike the industrial emission of carbon dioxide we’re familiar with today.

“Over the past 50 years, we’ve seen that a significant amount of oxygen has been lost from our modern oceans,” Them said. “While the timescales are different, past volcanism and carbon dioxide increases could very well be an analog for present events.”

When the atmosphere is suffused with carbon dioxide, global temperatures climb, triggering a cascade of hydrological, biological and chemical events that conspire to sap the oceans of oxygen.

Scientists have found evidence that several hundred thousand years before the T-OAE, volcanoes flooded Earth’s atmosphere with carbon dioxide, helping to set in motion the sequence of events that would ultimately result in oceanic deoxygenation and widespread marine life extinction.

While researchers have long surmised a link between volcanism, loss of oxygen and mass extinction, this study provides the first conclusive data.

“As a community, we’ve suggested that sediments deposited during the T-OAE were indicative of widespread oxygen loss in the oceans, but we’ve never had the data until now,” Them said.

Prehistorical examples of carbon dioxide deluges and suffocating oceanic deoxygenation provide a lesson in how Earth systems respond to a variable climate.

This analysis of the T-OAE, and the onset of deoxygenation that preceded it, is another in a lineage of reports that presage a bleak future for oceans with diminishing levels of oxygen.

“It’s extremely important to study these past events,” Them said. “It seems that no matter what event we observe in Earth’s history, when we see carbon dioxide concentrations increasing rapidly, the result tends to be very similar: a major or mass extinction event. This is another situation where we can unequivocally link widespread oceanic deoxygenation to a mass extinction.”

Steps can still be taken to curb oxygen loss in the modern oceans. For example, conserving important wetlands and estuaries — along with other environments that absorb and store large amounts of carbon dioxide — could help to blunt the effects of harmful industrial emissions.

But should our oceans’ oxygen contents continue to decline at their current rates, future marine organisms could be doomed to the same fate that befell their Jurassic ancestors.

“If you’re an oxygen-consuming organism, you don’t want to see major changes in marine oxygen levels,” Them said. “You either adapt or go extinct.”

Measurements for this study were conducted at the FSU-based National High Magnetic Field Laboratory. The research was funded by the National Science Foundation and the National Aeronautic and Space Administration.

Reference:
Theodore R. Them, Benjamin C. Gill, Andrew H. Caruthers, Angela M. Gerhardt, Darren R. Gröcke, Timothy W. Lyons, Selva M. Marroquín, Sune G. Nielsen, João P. Trabucho Alexandre, Jeremy D. Owens. Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction. Proceedings of the National Academy of Sciences, 2018; 201803478 DOI: 10.1073/pnas.1803478115

Note: The above post is reprinted from materials provided by Florida State University.

Oldest mammal in Brazil lived in the age of dinosaurs

June 12, 2018

Table of Contents

Brasilestes stardusti is the name given to the oldest known mammal found in Brazil. It lived in what is now the northwest of São Paulo State at the end of the Mesozoic Era between 87 million and 70 million years ago. It is the only Brazilian mammal known to have coexisted with the dinosaurs.

The discovery of Brasilestes was announced on May 30, 2018, by a team led by Max Langer, a professor at the University of São Paulo’s Ribeirão Preto School of Philosophy, Science & Letters (FFCLRP-USP). Langer’s team included colleagues at the Federal University of Goiás and the University of Campinas in Brazil, La Plata Museum in Argentina, and the Massachusetts Institute of Technology (MIT) in the US.

Physically speaking, Brasilestes consists of a fossilized premolar tooth with a maximum crown length of 3.5 mm. “The tooth is small and incomplete: the roots are missing,” said paleontologist Mariela Cordeiro de Castro, first author of the paper recently published in Royal Society Open Science.

“Small but not tiny,” Castro continued. “Although it’s only 3.5 mm, the Brasilestes tooth is three times bigger than all known Mesozoic mammal teeth. In the age of the dinosaurs, most mammals were the size of mice. Brasilestes was far larger, about the size of an opossum.”

The name of the new species pays tribute to British rock star David Bowie, who died in January 2016, a month after the fossil was found. Brasilestes stardusti alludes to Ziggy Stardust, an extraterrestrial character created by Bowie for a 1972 album.

The research was supported by the São Paulo Research Foundation—FAPESP as part of the thematic project “The origin and rise of dinosaurs in Gondwana (late Triassic-early Jurassic),” for which Langer is principal investigator.

The fossilized tooth was found in a rocky outcrop of the Adamantina Formation in General Salgado, São Paulo State. The rocks are in a field on a ranch called Fazenda Buriti.

“We were visiting Mesozoic outcrops when Júlio Marsola [another member of the team], keen-sighted as a lynx, spotted a small tooth sticking up out of a rock,” said Castro, a professor at the Federal University of Goiás (UFG).

“The General Salgado deposits are well-known. Several Mesozoic crocodiles have come from them. The particular outcrop where I found Brasilestes is interesting, with dozens of fragments of Mesozoic crocodile eggshells. I bent down to look more closely at a small part of the outcrop to see if there were any eggshells and spotted the tooth. If it had stayed out in the open like that for a few more days, the rain would have swept it away.

“When I noticed what appeared to resemble the base of the tooth’s two roots [the roots themselves have broken off], I thought it must be a mammal. Laboratory analysis gave us the certainty that it is indeed from a mammal.”

A placental mammal in the Botucatu Desert

While a mere 3.5 mm tooth, especially an incomplete one, may seem insufficient to describe a new species of mammal, in actual, fact extinct mammals are frequently described on the basis of a single fossilized tooth.

This is because teeth are the most durable part of the mammalian skeleton. After all, they have to withstand the wear and tear of chewing for an entire lifetime. In contrast, many fish species and reptiles, for example, grow new teeth continually throughout their lives. Indeed, mammalian teeth are often the only skeletal remains that stay intact long enough to become fossilized.

The fact that a single premolar is all that is left of Brasilestes and that it is incomplete prevented the researchers from distinguishing with absolute confidence the group of mammals to which the species belonged. They know the tooth belonged to a therian, a member of a large subclass of Mammalia that includes marsupials and placentals.

Although there is not enough evidence to support the inclusion of Brasilestes in either infraclass, the researchers believe (but cannot categorically conclude) it was a placental mammal. If so, the fossil is unique.

Today, there are three major groups of mammals, namely, placentals, marsupials and monotremes. All three evolved during the Mesozoic Era. At that time, however, they were by no means the only groups of mammals. There were also multituberculates, which were common in the northern hemisphere, as well as groups typical of the southern hemisphere such as meridiolestids and gondwanatherians—named for Gondwana, the ancient southern supercontinent that gave rise to Africa, South America, Australia, Antarctica, and India.

The first Mesozoic mammal fossils were found in Argentinian Patagonia in the early 1980s, and some 30 species are now known. Until the Brasilestes announcement, these were the only ones found in South America. None remotely resembles the little tooth found in Brazil.

“When I showed the Brasilestes fossil to Edgardo Ortiz-Jaureguizar, a paleontologist at La Plata Museum, he was very surprised. He said he’d never seen anything like it, and at once showed it to another specialist at the same institution, Francisco Goin, who had the same reaction. Goin said Brasilestes resembled no other Mesozoic mammal found in Argentina, hence in South America,” Castro recalled.

Among the 30-odd Argentinian species of Mesozoic mammals, there are meridiolestids, gondwanatherians, and even a few suspected multituberculates. There are no marsupials or placentals. The only fossils in these two groups found in South America date from after the mass extinction that wiped out the dinosaurs 66 million years ago in an event that marks the end of the Mesozoic and the onset of the current geological era, the Cenozoic.

Until the discovery of Brasilestes, the only traces of Mesozoic mammals in Brazil were hundreds of tracks and footprints left by unknown creatures 130 million years ago as they traversed the dunes of the Botucatu Desert in what is now São Paulo State. The solidified surface of those dunes has been preserved as sandstone slabs on which the footprints can be seen.

In 1993, Reinaldo José Bertini , a professor at São Paulo State University (UNESP) in Rio Claro, announced the discovery of a mammalian jawbone fragment with a single tooth far smaller than the Brasilestes premolar. However, Bertini did not publish a detailed study of the fossil and therefore could not name a new species.

“Brasilestes is not just the first Brazilian Mesozoic mammal to be described but also one of the few Mesozoic mammals found in more central regions of South America. The Argentinian fossils were found in geological formations in Patagonia, the southern tip of the continent,” Langer said.

“Furthermore, Brasilestes is different from everything found before, suggesting that possibly placental mammals inhabited South America between 87.8 million and 70 million years ago,” said the FAPESP thematic project coordinator.

New species possibly related to a mammal from India

Even more surprisingly, the Mesozoic mammal with premolars that most resemble the Brasilestes tooth lived on the other side of the world, in India, between 70 million and 66 million years ago. Its name is Deccanolestes. No other creature in the global fossil record is so similar to Brasilestes.

How could two members of the same lineage have lived so far apart in unconnected regions? Approximately 100 million years ago, when South America and Africa had only just been separated by the opening of the South Atlantic, India was breaking away from Gondwana and starting to wander through the Indian Ocean.

This implies that at least 100 million years ago, the ancestors of Brasilestes and Deccanolestes populated the Gondwana supercontinent. In other words, the lineage to which Brasilestes and Deccanolestes belong is far older than the ages of their fossils—between 87 million and 70 million years ago for Brasilestes, and between 70 million and 66 million for Deccanolestes.

“The discovery of Brasilestes raises many more questions than answers about the biogeography of South American Mesozoic mammals,” Langer said. “Thanks to Brasilestes, we’ve realized that the history of Gondwana’s mammals is more complex than we thought.”

Finding triggers speculation on xenarthrans’ origins

This could give rise to new hypotheses and new lines of investigation. Who knows, for example, whether future research inspired by the discovery of Brasilestes will reveal the origin of a typical South American group, the xenarthrans, the order of armadillos, anteaters and sloths? Castro’s main research interest, in fact, is the evolutionary history of the xenarthrans.

“An interesting feature of the Brasilestes premolar is its superthin enamel, which is only 20 micrometers thick. The Brasilestes enamel is the thinnest of any Cretaceous mammal in the fossil record. Most Mesozoic mammals have enamel in the range of 100 to 300 micrometers,” Castro said.

“Tens of known species of xenarthrans are alive now. Hundreds are extinct. Only three have enamel. The microstructure of Brasilestes’ premolar enamel is very similar to that of the nine-banded armadillo,” said the FAPESP-supported researcher.

According to Castro, “molecular clock evidence suggests the xenarthran lineage started at least 85 million years ago. However, the oldest armadillo fossils, found in Rio de Janeiro, are about 50 million years old”.

While it is intriguing to imagine Brasilestes as an ancient xenarthran, it is far too soon for any such affirmation.

“The age and provenance of Brasilestes do match molecular hypotheses for the origin of the xenarthrans, but it would be premature to infer taxonomic affinity in light of the morphological differences between the Brasilestes tooth and armadillo teeth,” Castro said.

Langer agreed. “We have only one Brasilestes fossil. That’s nowhere near enough to extract conclusions from the fossil record,” he said.

The fact that no Mesozoic mammal fossils were found in Brazil before Brasilestes could mean such fossils are rare or too fragile to be preserved. “Who knows, one day we may find new Brasilestes fossils that help us understand its history better. It could take decades,” Langer said.

Reference:
Mariela C. Castro et al, A Late Cretaceous mammal from Brazil and the first radioisotopic age for the Bauru Group, Royal Society Open Science (2018). DOI: 10.1098/rsos.180482

Note: The above post is reprinted from materials provided by FAPESP.

International collaboration studies the predictability of earthquakes

June 12, 2018

Since 2007, the Collaboratory for the Study of Earthquake Predictability or CSEP has been studying earthquake forecast models to find out how well each model stacks up against its competitors, and how well each forecast predicts later seismic activity.

At four centers in California, New Zealand, Europe and Japan—and in countless labs across the globe—CSEP’s experiments and its rigorous testing procedures have shed light on the predictability of earthquakes, according to a special focus section published June 13 in Seismological Research Letters.

“The fundamental idea of CSEP is simple in principle but complex in practice: forecasting models should be tested against future observations to assess their performance, thereby ensuring an unbiased test of the forecasting power of a model,” said Danijel Schorlemmer of GFZ Potsdam in Germany, who wrote about CSEP’s achievements for the journal.

At each of its four testing centers (development of a fifth center in China is underway), earthquake forecasts generated automatically from a set of models are compared with the region’s observed seismicity. The CSEP experiments are governed by strict rules that include a precise description of the region under study and the high quality of the seismic recordings, among other criteria. The experiments test how well the number, the distribution and the magnitudes of observed earthquakes in a region match up with a forecast’s predictions.

In Italy, for example, there are three CSEP experiments underway to evaluate one-day, three-month and five year earthquake forecasts for the country. As Matteo Taroni and colleagues write in the focus section, the one-day forecasts have proved useful enough for the models to be incorporated into Italy’s Department of Civil Protection’s seismic forecasts.

CSEP center experiments conducted from 2008 to 2017, a time period that included major earthquakes such as the 2011 magnitude 6.2 Christchurch quake and the 2016 magnitude 7.8 Kaikoura earthquake, provided data used to refine real-time community warnings during these major earthquakes, according to David Rhoades of GNS Science and colleagues.

With some caveats, the lessons learned from CSEP experiments can be used to evaluate “classic” forecasts with an eye to making future forecasts more testable. In his focus paper, UCLA emeritus David D. Jackson applied CSEP tests to the 1988 30-year forecast developed by the Working Group on California Earthquake Probabilities for 16 areas of the San Andreas, Hayward, San Jacinto and Imperial faults. He concluded that only one quake, the magnitude 6 Parkfield earthquake in 2004, is associated with the 1988 forecast.

Researchers have also used CSEP to test candidate seismicity models to use in forecasting. One example comes from a focus paper by Camilla Cattania of Stanford University and colleagues, who looked at how the widely-known earthquake triggering mechanism called the static Coulomb stress hypothesis, which suggests stress changes in deformed geological material can move through faults to promote new tremors, can be used in forecasting. Their analysis, applied to the 2010-2012 Canterbury earthquake sequence in New Zealand, suggests physics-based models such as the Coulomb model are more promising for forecasting than previously thought, especially in combination with other statistical models.

The future of CSEP will include more types of earthquake modeling, including combination models, 3-D models and more physics-based modeling, along with expanded use of seismic datasets from Asia and South America, said Schorlemmer.

More information: “Preface to the Focus Section on the Collaboratory for the Study of Earthquake Predictability (CSEP): New Results and Future Directions,” Seismological Research Letters (2018).

“The Collaboratory for the Study of Earthquake Predictability: Achievements and Priorities,” Seismological Research Letters (2018).

“Prospective CSEP evaluation of 1-day, 3-month, and 5-year earthquake forecasts for Italy,” Seismological Research Letters (2018).

“Highlights from the first ten years of the New Zealand Earthquake Forecast Testing Center,” Seismological Research Letters (2018).

“The forecasting skill of physics-based seismicity models during the 2010-2012 Canterbury, New Zealand, earthquake sequence,” Seismological Research Letters (2018).

“Ranking some global forecasts with the Kagan information score,” Seismological Research Letters (2018).

“Exploring magnitude forecasting of the next earthquake,” Seismological Research Letters (2018).

“Ensemble smoothed seismicity models for the new Italian probabilistic seismic hazard map,” Seismological Research Letters (2018).

“Prospective evaluation of global earthquake forecast models: Two years of observations support merging smoothed seismicity with geodetic strain rates,” Seismological Research Letters (2018).

Note: The above post is reprinted from materials provided by Seismological Society of America.

‘Monstrous’ new Russian saber-tooth fossils clarify early evolution of mammal lineage

June 9, 2018

The therocephalian Gorynychus masyutinae, top predator of the Kotelnich fossil assemblage, hunting a tree-dwelling herbivore (Suminia getmanovi). Art by Matt Celeskey.

Fossils representing two new species of saber-toothed prehistoric predators have been described by researchers from the North Carolina Museum of Natural Sciences (Raleigh, USA) and the Vyatka Paleontological Museum (Kirov, Russia). These new species improve the scientists’ understanding of an important interval in the early evolution of mammals — a time, between mass extinctions, when the roles of certain carnivores changed drastically.

Living mammals are descended from a group of animals called therapsids, a diverse assemblage of “protomammals” that dominated terrestrial ecosystems in the Permian Period (~299-252 million years ago), millions of years before the earliest dinosaurs. These protomammals included tusked herbivores, burrowing insectivores, and saber-toothed predators. The vast majority of Permian therapsids have been found in the Karoo Basin of South Africa, and as a result, the South African record has played an outsized role influencing scientists’ understanding of protomammal evolution. Because of this, therapsid fossils from outside of South Africa are extremely important, allowing scientists to discern whether observed events in the protomammal fossil record represent global or merely regional patterns.

Recent expeditions by the Vyatka Paleontological Museum have collected a wealth of spectacularly-preserved Permian fossils near the town of Kotelnich along the Vyatka River in European Russia. These fossil discoveries include the remains of two previously unknown species of predatory protomammals, newly described in the journal PeerJ by Christian Kammerer of the North Carolina Museum of Natural Sciences and Vladimir Masyutin of the Vyatka Paleontological Museum. The first of the two new species, Gorynychus masyutinae, was a wolf-sized carnivore representing the largest predator in the Kotelnich fauna. The second new species, Nochnitsa geminidens, was a smaller, long-snouted carnivore with needle-like teeth. Gorynychus belongs to a subgroup of protomammals called therocephalians (“beast heads”), whereas Nochnitsa belongs to a different subgroup called gorgonopsians (“gorgon faces”).

Both new species are named after legendary monsters from Russian folklore, befitting their menacing appearances. Gorynychus is named after Zmey Gorynych, a three-headed dragon, and Nochnitsa is named after a malevolent nocturnal spirit. (Based on their relatively large eye sockets, it is likely that Nochnitsa and its relatives were nocturnal.)

Gorynychus and Nochnitsa improve scientists’ understanding of ecosystem reorganization after the mid-Permian extinction (260 mya). Although not as well-known as the more devastating end-Permian mass extinction (252 mya, which nearly wiped out protomammals), the mid-Permian mass extinction also played a major role in shaping the course of protomammal evolution. In typical late Permian ecosystems, the top predators were giant (tiger-sized), saber-toothed gorgonopsians and therocephalians were generally small insectivores. In mid-Permian ecosystems, by contrast, these roles are reversed. At Kotelnich, the saber-toothed top predator Gorynychus is a therocephalian and the only gorgonopsians are much smaller animals.

“In between these extinctions, there was a complete flip-flop in what roles these carnivores were playing in their ecosystems — as if bears suddenly became weasel-sized and weasels became bear-sized in their place,” says Kammerer. The new species from Russia provide the first evidence that there was a worldwide turnover in predators after the mid-Permian extinction, and not just a localized turnover in South Africa.

Kammerer adds, “Kotelnich is one of the most important localities worldwide for finding therapsid fossils — not only because they are amazingly complete and well-preserved there, but also because they provide an all-too-rare window into mammal ancestry in the Northern Hemisphere during the Permian.”

Reference:
Christian F. Kammerer, Vladimir Masyutin. A new therocephalian (Gorynychus masyutinae gen. et sp. nov.) from the Permian Kotelnich locality, Kirov Region, Russia. PeerJ, 2018; 6: e4933 DOI: 10.7717/peerj.4933

Note: The above post is reprinted from materials provided by North Carolina Museum of Natural Sciences.

Minerology on Mars points to a cold and icy ancient climate

June 9, 2018

Herðubreið Volcano in Iceland — Researchers expect the volcanoes in Mars’ Sisyphi Planum region to look similar to subglacial volcanoes on earth, such as Herðubreið in Iceland. Credit: Purdue University photo/Sheridan Ackiss

The climate throughout Mars’ early history has long been debated — was the Red Planet warm and wet, or cold and icy? New research published in Icarus provides evidence for the latter.

Mars is littered with valley networks, deltas and lake deposits, meaning it must have had freely flowing water at some point, probably around 4 billion years ago. But climate models of the planet’s deep past haven’t been able to produce warm enough conditions to allow liquid water on the surface.

“There are people trying to model Mars’ ancient climate using the same kind of models we use here on Earth, and they’re having a really hard time doing it. It’s difficult to create a warm ancient Mars because the sun was a lot fainter then. The whole solar system was cooler,” said Briony Horgan, an assistant professor of earth, atmospheric and planetary sciences at Purdue University. “While a lot of people are using climate models, we’re coming at this from a unique perspective — what does the volcanic record of Mars tell us?”

Volcanism was abundant throughout Mars’ early history. There are large, broad volcanoes on some of the planet’s widely studied regions, but less is known about a region of low and smooth topography in the southern highlands known as Sisyphi Planum. Here, there are more than 100 flat-topped mounds known as the Sisyphi Montes, which could be volcanic in origin.

When volcanoes erupt beneath ice sheets and glaciers on Earth, the combination of heat and melt water create flat-topped, steep-sided mountains called “tuyas,” or table mountains. When subglacial eruptions don’t breach the surface of the ice, the tops of the volcanoes remain cone-shaped instead of becoming flat. The minerology produced during these events is unique due to the interaction between hot lava and cold glacial meltwater.

Sheridan Ackiss, a Ph.D. candidate at Purdue and lead author of the paper, used images from NASA’s Compact Reconnaissance Imaging Spectrometers for Mars (CRISM) to find out if the mineral makeup of the region was consistent with subglacial volcanism.

CRISM detects both the visible range and shorter wavelengths of light, which helps the instrument’s operators identify a broad range of minerals on the Martian surface. At visible wavelengths, the way light is reflected is strongly influenced by iron, whereas at infrared wavelengths, CRISM can pick up features from carbonate, sulfate, hydroxyl and water incorporated in mineral crystals.

“Each rock has a specific fingerprint, and you can identify that with reflections of light,” Ackiss said.

The findings identify three distinct mineral combinations in the region, dominated by gypsum, polyhydrated sulfates and a smectite-zeolite-iron oxide mixture — all of which have been associated with volcanoes in glacial environments.

“We now have two sets of data, minerals and morphology, that say there had to have been ice on Mars at some point in time,” said Ackiss. “And it was probably relatively late in Mars’ history.”

Ackiss’ team hopes their findings can be used as a reference point for other regions on Mars with a volcanic history. If researchers could find evidence for volcanic activity under ice sheets elsewhere, it would solidify the case for a very cold ancient Mars. But fear not, space enthusiasts, this doesn’t eliminate the possibility of past life on Mars.

“Even if Mars was a cold and icy wasteland, these volcanic eruptions interacting with ice sheets could have created a little happy place for microbes to exist,” Horgan said. “This is the kind of place you’d want to go to understand how life would’ve survived on Mars during that time.”

Reference:
S. Ackiss, B. Horgan, F. Seelos, W. Farrand, J. Wray. Mineralogic evidence for subglacial volcanism in the Sisyphi Montes region of Mars. Icarus, 2018; 311: 357 DOI: 10.1016/j.icarus.2018.03.026

Note: The above post is reprinted from materials provided by Purdue University. Original written by Kayla Zacharias.

Tiny paragliding beetle that lived with dinosaurs discovered in amber, named ‘Jason’

June 7, 2018

Featherwing beetles are smaller than the period at the end of this sentence. They get their name from the feathery fringe on their wings that enables them to catch the air and float like dandelion seeds. And, it turns out, they go way back — scientists discovered a 99-million-year-old featherwing beetle preserved in amber, and they named it “Jason.”

“This tiny beetle lived during the Cretaceous Period, it saw actual dinosaurs,” says Shuhei Yamamoto, a researcher at the Field Museum in Chicago and co-lead author of a paper describing the beetle in Cretaceous Research. “The amber the beetle was found in is like a time capsule.”

The new beetle, the earliest member of its family to get a scientific name, is called Kekveus jason. “Jason” is a reference to the Greek hero who sailed the world in search of the Golden Fleece; “Kekveus,” meanwhile, doesn’t mean anything — co-lead author Vasily Grebennikov of the Canadian Food Inspection Agency, picked it because new genus names for little-known fossils often wind up changing when the species is later reclassified as scientists learn more about it. “From my perspective I always believe that an animal name should not have any meaning (except when named after a person), since if the authors are wrong, it might be odd to have later species ‘chinensis’ endemic to Europe, or something similarly absurd,” says Grebennikov.

Yamamoto discovered the tiny sailing insect by poring over pieces of amber. Amber is made from fossilized resin, a sap-like substance produced by plants. When prehistoric insects got trapped in resin, their bodies would get incorporated into the amber that formed — think the mosquitos from Jurassic Park, minus the “resurrecting dinosaurs” part.

When Yamamoto spotted a tiny black speck in the amber, he was cautiously optimistic that he’d found a prehistoric insect. “I didn’t have much confidence at first, but after cutting and polishing the amber so I could get a better look, I realized, oh, this is truly an amazing fossil,” he says.

The beetle is only 0.536 millimeters long — it’s dwarfed by the tip of a mechanical pencil. But under a microscope, Yamamoto was able to glean details of its anatomy that revealed it as a different species and genus from living featherwing beetles. For instance, it has three grooves running like pinstripes up its body, a feature not found on its modern cousins. Overall, though, the researchers found that K. jason has a lot in common with featherwings alive today, meaning that the family of beetles evolved features like a tiny body size and fringed wings millions of years ago. According to Yamamoto, amber fossils yield a level of preservation rarely found in regular rock, especially for insects. “There are many rock fossils from the Jurassic and Cretaceous periods, but they’re limited to big animals like larger insects, mammals, dinosaurs, and birds, because small insects cannot be preserved in rock fossil very clearly. Only fossil insects in amber are preserved in fine detail, in three dimensions,” says Yamamoto. Yamamoto looks forward to further discoveries of prehistoric animals preserved in amber. “It’s likely that we’ll find more in the future — Burmese amber is one of the hottest fossils in the world,” he says. “There are so many great findings happening, literally day by day. Many important discoveries of insects will be made.”

Reference:
Shûhei Yamamoto, Vasily V. Grebennikov, Yui Takahashi. Kekveus jason gen. et sp. nov. from Cretaceous Burmese amber, the first extinct genus and the oldest named featherwing beetle (Coleoptera: Ptiliidae: Discheramocephalini). Cretaceous Research, 2018; DOI: 10.1016/j.cretres.2018.05.016

Note: The above post is reprinted from materials provided by Field Museum. The original story is licensed under a Creative Commons License.

Jurassic diet: Why our knowledge of what ancient pterosaurs ate might be wrong

June 7, 2018

Restoration of the giant azhdarchid pterosaur Hatzegopteryx catching an unsuspecting dinosaur for supper. In addition to carnivory, azhdarchids have been hypothesized to have eaten fish, insects, fruits, hard-shelled organisms or a combination of them all. Credit: Mark P. Witton/CC BY 4.0

Whenever we think about extinct animals we often imagine them eating their favourite meals, whether it be plants, other animals or a combination of both.

But are our ideas about extinct diets grounded within scientific reasoning, or are they actually little more than conjecture and speculation?

New research, published in Biological Reviews and led by a team of palaeobiologists from the University of Leicester, has revealed that the diets of pterosaurs are largely based on ideas that have been uncritically accepted for decades, or even centuries — and may often be wrong.

The study shows that one group of extinct animals where our dietary knowledge is lacking are the pterosaurs; extinct flying reptiles who lived in the Mesozoic Period 215-66 million years ago.

The research involved a comprehensive analysis of the scientific literature, summarising over 300 statements from 126 studies about the diets of pterosaurs, and the types of evidence used to support ideas of what they ate.

The research shows the vast majority of ideas about pterosaur diet are based on inferences drawn from modern organisms and/or the environments in which pterosaur fossils are preserved. These are not always reliable.

Jordan Bestwick, a PhD student from the School of Geography, Geology and the Environment, and lead author of the study, said: “Working out the diets of extinct animals is vitally important for understanding how they fitted within their respective ecosystems, which can tell us about how present ecosystems function and may change in the future.

“Being able to robustly test ideas is a key attribute of the scientific process, and helps us fully understand what we can know about the lifestyles of extinct animals, and what we can never know.”

Analysis reveals that over sixty percent of all hypotheses of pterosaur diet are based on simplistic anatomical comparisons between pterosaurs and modern organisms, particularly of the skulls and teeth. A key problem with this is that many of these interpretations are difficult, if not impossible, to test.

Jordan explained: “The potential range of pterosaur diets has been reviewed in the past but little attention has been paid to the evidence, if any, that support dietary interpretations. We realised that not only was it important to discover what we know about pterosaur diets, but to also find out how we know what we know about pterosaur diets.

“We find for some pterosaurs there is strong agreement among researchers as to their likely diet. Pteranodontids for example, which include one of the best known pterosaurs, Pteranodon, are almost unanimously agreed to have been fish feeders, an idea that is independently supported by multiple lines of evidence.

“In contrast, there is far less agreement as to what the giant azhdarchid pterosaurs ate. Azhdarchids can reach sizes of up to 10 metres or more in wingspan, like Hatzegopteryx, and there have been at least six different diets argued for these pterosaurs.”

This is not to say there are no methods or techniques that yield reliable evidence for understanding diets in these extinct animals. Biomechanical analysis of how hard pterosaurs could bite, and flight modelling that predicts how pterosaurs may have foraged for food have proven useful for understanding what some pterosaurs may or may not have eaten.

However techniques like these are employed in a small minority of studies and as such, it is currently not possible to identify the biological reasons that might explain the range and diversity of pterosaurs diets.

Dr David Hone from the Queen Mary University of London, who was not involved in the study, commented: “This is an important summary of what we know (and what we don’t) about what these animals fed on. This gives pterosaur researchers an excellent and critical starting point and a roadmap for future research on the diets of pterosaurs, and more broadly for all extinct animals.”

Reference:
Jordan Bestwick, David M. Unwin, Richard J. Butler, Donald M. Henderson, Mark A. Purnell. Pterosaur dietary hypotheses: a review of ideas and approaches. Biological Reviews, 2018; DOI: 10.1111/brv.12431

Note: The above post is reprinted from materials provided by University of Leicester.

Scientists use 4D scanning to predict behavior of volcanoes

June 7, 2018

Scientists are using the latest in 4D technology to predict the behaviour of lava flows and its implications for volcanic eruptions.

The results explain why some lava flows can cover kilometres in just a few hours, whilst others travel more slowly during an eruption, highlighting the hazard posed by fast-moving flows which often pose the most danger to civilian populations close to volcanoes.

The research, which is being led by The University of Manchester, is studying the processes which happen during crystallisation in basaltic magmas using 4D synchrotron X-ray microtomography. It is the first time this kind of 4D scanning technology has been used for investigating crystallisation during volcanic eruptions and for simulating the behaviour of a natural lava flow. The study was recently published in Nature Scientific Reports.

The team, led by Prof Mike Burton, Chair of Volcanology at the University, monitored crystallisation in magmas, a fundamental process that drives eruptions and controls different kinds of volcanic activity. Using this new and novel approach and technology they can, for the first time, watch the crystals grow in 3D in real-time, simulating the behaviour of lava flows once a volcano has erupted. The process is similar to scenes recently witnessed at Kilauea in Hawaii.

Prof Burton explains: “During volcanic eruptions small crystals grow within magma. These crystals can greatly change the way magma flows. Simply put, the more crystals there are the slower the eruption will be which also reduces the speed and distance travelled by lava flows.”

“The fewer crystals present in the lava means the eruption will speed up, potentially becoming more powerful and devastating. Our research and this new approach open an entirely new frontier in the study of volcanic processes.” To study the rate of crystal growth the team set up a sample from a real eruption in a high temperature cell, before performing X-ray CAT scans whilst controlling the temperature of the magma. This allowed the team to visualise the formation and growth of crystals, and measure how quickly they grew.

Using this method and technology the researchers can collect hundreds of 3D images during a single experiment. This data is then used in complex, numerical models to fully characterise the behaviour of volcanic eruptions more accurately.

Dr Margherita Polacci, from Manchester’s School of Earth and Environmental Sciences, and study’s lead author, said: “Being able to more accurately predict the behaviour of lava flows could also allow us to help relevant safety agencies devise and develop new safety strategies and actions when dealing with eruptions in populated areas.”

This isn’t the only use for such technology in Geosciences. Prof Burton added: “There are many more applications of this approach in materials science, mineral extraction and other geological processes. We are very excited about the prospect of extending our studies to high pressures, which we will be doing in further experiments in 2018.”

Reference:
M. Polacci, F. Arzilli, G. La Spina, N. Le Gall, B. Cai, M. E. Hartley, D. Di Genova, N. T. Vo, S. Nonni, R. C. Atwood, E. W. Llewellin, P. D. Lee, M. R. Burton. Crystallisation in basaltic magmas revealed via in situ 4D synchrotron X-ray microtomography. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-26644-6

Note: The above post is reprinted from materials provided by University of Manchester.

Researchers report the earliest fossil footprints

June 7, 2018

Trackways and burrows excavated in situ from the Ediacaran Dengying Formation. Credit: NIGP

On July 20, 1969, Neil Armstrong put the first human footprint on the moon. But when did animals leave the first footprint on Earth?

Recently, an international research team reported discovering fossil footprints for animal appendages in the Ediacaran Period (about 635-541 million years ago) in China. This is considered the earliest animal fossil footprint record. The research was published in Science Advances on June 6, 2018.

Bilaterian animals such as arthropods and annelids have paired appendages and are among the most diverse animals today and in the geological past. They are often assumed to have appeared and radiated suddenly during the Cambrian Explosion about 541 to 510 million years ago, although it has long been suspected that their evolutionary ancestry was rooted in the Ediacaran Period. Until the current discovery, however, no fossil record of animal appendages had been found from the Ediacaran Period.

Researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and Virginia Tech in the United States studied trackways and burrows discovered in the Ediacaran Shibantan Member of the Dengying Formation (551-541 million years ago) in the Yangtze Gorges area of South China. The trackways are somewhat irregular, consisting of two rows of imprints that are arranged in series or repeated groups.

The characteristics of the trackways indicate that they were produced by bilaterian animals with paired appendages that raised the animal body above the water-sediment interface. The trackways appear to be connected to burrows, suggesting that the animals may have periodically dug into sediments and microbial mats, perhaps to mine oxygen and food.

These trace fossils represent some of the earliest known evidence for animal appendages and extend the earliest trace fossil record of animals with appendages from the early Cambrian to the late Ediacaran Period. The body fossils of the animals that made these traces, however, have not yet been found. It is possible that such remains were never preserved.

Reference:
“Late Ediacaran trackways produced by bilaterian animals with paired appendages” Science Advances (2018). advances.sciencemag.org/content/4/6/eaao6691

Note: The above post is reprinted from materials provided by Chinese Academy of Sciences.

First tetrapods of Africa lived within the Devonian Antarctic Circle

June 7, 2018

Full reconstruction of Waterloo Farm by Maggie Newman including Tutusius and Umzantsia. Credit: Maggie Newman

Table of Contents

The first African fossils of Devonian tetrapods (four-legged vertebrates) show these pioneers of land living within the Antarctic circle, 360 million years ago.

The evolution of tetrapods from fishes during the Devonian period was a key event in our distant ancestry. Newly found fossils from the latest Devonian Waterloo Farm locality near Grahamstown in the Eastern Cape, South Africa, published today in Science, force a major reassessment of this event. “Whereas all previously found Devonian tetrapods came from localities which were in tropical regions during the Devonian, these specimens lived within the Antarctic circle,” explains lead author, Dr. Robert Gess of the Albany Museum in Grahamstown, and co-author Professor Per Ahlberg of Uppsala University in Sweden. The research was supported by the South African DST-NRF Centre of Excellence in Palaeosciences, based at the University of the Witwatersrand and the Millennium Trust.

The first African Devonian tetrapods

Two new species, named Tutusius and Umzantsia, are Africa’s earliest known four-legged vertebrates by a remarkable 70 million years. The approximately metre-long Tutusius umlambo (named in honour of Archbishop Emeritus Desmond Tutu) and the somewhat smaller Umzantsia amazana are both incomplete. Tutusius is represented by a single bone from the shoulder girdle, whereas Umzantsia is known from a greater number of bones, but they both appear similar to previously known Devonian tetrapods. Alive, they would have resembled a cross between a crocodile and a fish, with a crocodile-like head, stubby legs, and a tail with a fish-like fin.

The Waterloo Farm locality (where the tetrapods were discovered) is a roadcut first revealed in 2016 after controlled rock-cutting explosions by the South African National Roads Agency (SANRAL) along the N2 highway between Grahamstown and the Fish River. This cutting exposed dark grey mudstones of the Witpoort Formation that represent an ancient environment of a brackish, tidal river estuary that contain abundant fossils of animals and plants.

The first tetrapod found outside of tropical regions

The real importance of Tutusius and Umzantsia lies in where they were found.

Devonian tetrapod fossils are found in widely scattered localities. However, if the continents are mapped back to their Devonian positions, it emerges that all previous finds are from rocks deposited in the palaeotropics—between 30 degrees north and south of the equator. Almost all come from Laurussia, a supercontinent that later fragmented into North America, Greenland and Europe.

The much larger southern supercontinent, Gondwana, which incorporated present-day Africa, South America, Australia, Antarctica, and India, has hitherto yielded almost no Devonian tetrapods, with only an isolated jaw (named Metaxygnathus) and footprints, being found in eastern Australia. Because Australia was the northernmost part of Gondwana, extending into the tropics, an assumption developed that tetrapods evolved in the tropics, most likely in Laurussia. By extension it was assumed that movement of vertebrates from water onto land (terrestrialisation) also occurred in the tropics. Attempts to understand the causes of these major macroevolutionary steps therefore focussed on conditions prevalent in tropical water bodies.

The Waterloo Farm tetrapods not only come from Gondwana, but from its southernmost part: reconstructed to have been more than 70 degrees south, within the Antarctic circle. Abundant plant fossils show that forests grew nearby, so it wasn’t frozen, but it was definitely not tropical and during winter it will have experienced months of complete darkness. This finding changes our understanding of the distribution of Devonian tetrapods. We now know that tetrapods occurred throughout the world by the Late Devonian and that their evolution and terrestrialisation could realistically have occurred anywhere.

South Africa now adds insights into the emergence of land animals to its incredible fossil record, which also includes transition to mammals from reptile-like ancestors and the evolution of humans. There is probably not another country on the planet that so fully documents the long and dramatic evolutionary history of our own lineage.

Reference:
R. Gess at Albany Museum in Grahamstown, South Africa el al., “A tetrapod fauna from within the Devonian Antarctic Circle,” Science (2018). DOI: 1126/science.aaq1645

Note: The above post is reprinted from materials provided by Wits University.

Earth could have supported continental crust, life earlier than thought

June 7, 2018

Scientists studied 3.9-billion-year-old rocks from Nuvvuagittuq, Canada, and found evidence for an earlier formation of the crust. Credit: Elizabeth Bell

The early Earth might have been habitable much earlier than thought, according to new research from a group led by University of Chicago scientists.

Counting strontium atoms in rocks from northern Canada, they found evidence that the Earth’s continental crust could have formed hundreds of millions of years earlier than previously thought. Continental crust is richer in essential minerals than younger volcanic rock, which would have made it significantly friendlier to supporting life.

“Our evidence, which squares with emerging evidence including rocks in western Australia, suggests that the early Earth was capable of forming continental crust within 350 million years of the formation of the solar system,” said Patrick Boehnke, the T.C. Chamberlin Postdoctoral Fellow in the Department of Geophysical Sciences and the first author on the paper. “This alters the classic view, that the crust was hot, dry and hellish for more than half a billion years after it formed.”

One of the open questions in geology is how and when some of the crust — originally all younger volcanic rock — changed into the continental crust we know and love, which is lighter and richer in silica. This task is made harder because the evidence keeps getting melted and reformed over millions of years. One of the few places on Earth where you can find bits of crust from the very earliest epochs of Earth is in tiny flecks of apatite imbedded in younger rocks.

Luckily for scientists, some of these “younger” minerals (still about 3.9 billion years old) are zircons — very hard, weather-resistant minerals somewhat similar to diamonds. “Zircons are a geologist’s favorite because these are the only record of the first three to four hundred million years of Earth. Diamonds aren’t forever — zircons are,” Boehnke said.

Plus, the zircons themselves can be dated. “They’re like labeled time capsules,” said Prof. Andrew Davis, chair of the Department of Geophysical Sciences and a coauthor on the study.

Scientists usually look at the different variants of elements, called isotopes, to tell a story about these rocks. They wanted to use strontium, which offers clues to how much silica was around at the time it formed. The only problem is that these flecks are absolutely tiny — about five microns across, the diameter of a strand of spider silk — and you have to count the strontium atoms one by one.

This was a task for a unique instrument that came online last year: the CHicago Instrument for Laser Ionization, or CHILI. This detector uses lasers that can be tuned to selectively pick out and ionize strontium. When they used CHILI to count strontium isotopes in rocks from Nuvvuagittuq, Canada, they found the isotope ratio suggested plenty of silica was present when it formed.

This is important because the makeup of the crust directly affects the atmosphere, the composition of seawater, and nutrients available to any budding life hoping to thrive on planet Earth. It also may imply there were fewer meteorites than thought pummeling the Earth at this time, which would have made it hard for continental crust to form.

“Having continental crust that early changes the picture of early Earth in a number of ways,” said Davis, who is also a professor with the Enrico Fermi Institute. “Now we need a way for the geologic processes that make the continents to happen much faster; you probably need water and magma that’s about 600 degrees Fahrenheit less hot.”

The study is also confluent with a recent paper by Davis and Boehnke’s colleague Nicolas Dauphas, which found evidence for rain falling on continents 2.5 billion years ago, earlier than previously thought.

Reference:
Patrick Boehnke, Elizabeth A. Bell, Thomas Stephan, Reto Trappitsch, C. Brenhin Keller, Olivia S. Pardo, Andrew M. Davis, T. Mark Harrison, Michael J. Pellin. Potassic, high-silica Hadean crust. Proceedings of the National Academy of Sciences, 2018; 201720880 DOI: 10.1073/pnas.1720880115

Note: The above post is reprinted from materials provided by University of Chicago. Original written by Louise Lerner.

New insight into Earth’s crust, mantle and outer core interactions

June 5, 2018

A new study by the University of Liverpool, in collaboration with the Universities of Lancaster and Oslo, sheds light on a longstanding question that has puzzled earth scientists.

Using previously unavailable data, researchers confirm a correlation between the movement of plate tectonics on the Earth’s surface, the flow of mantle above the Earth’s core and the rate of reversal of the Earth’s magnetic field which has long been hypothesised.

In a paper published in the journal Tectonophysics, they suggest that it takes around 120-130 million years for slabs of ancient ocean floor to sink (subduct) from the Earth’s surface to a sufficient depth in the mantle where they can cool the core, which in turn causes the liquid iron in the Earth’s outer core to flow more vigorously and produce more reversals of the Earth’s magnetic field.

This study is the first to demonstrate this correlation using records and proxies of global rates of subduction from various sources including a continuous global plate reconstruction model developed at the University of Sydney. These records were compared with a new compilation of magnetic field reversals whose occurrence is locked into volcanic and sedimentary rocks.

Liverpool palaeomagnetist, Professor Andy Biggin, said: “Until recently we did not have good enough records of how much global rates of subduction had changed over the last few hundreds of millions of years and so we had nothing to compare with the magnetic records.

“When we were able to compare them, we found that the two records of subduction and magnetic reversal rate do appear to be correlated after allowing for a time delay of 120-130 million years for the slabs of ocean floor to go from the surface to a sufficient depth in the mantle where they can cool the core.

“We do not know for sure that the correlation is causal but it does seem to fit with our understanding of how the crust, mantle and core should all be interacting and this value of 120-130 million could provide a really useful observational constraint on how quickly slabs of ancient sea floor can fall through the mantle and affect flow currents within it and in the underlying core.”

The magnetic field is generated deep within the Earth in a fluid outer core of iron and other elements that creates electric currents, which in turn produces magnetic fields.

The core is surrounded by a nearly 3,000 km thick mantle which although made of solid rock, flows very slowly (mm per year). The mantle produces convection currents which are strongly linked to movement of the tectonic plates but also affect the core by varying the amount of heat that is transferred across the core-mantle boundary.

The Earth’s magnetic field occasionally flips its polarity and the average length of time between such flips has changed dramatically through Earth’s history. For example, today such magnetic reversals occur on average four times per million years but one hundred million years ago, the field essentially stayed in the same polarity for nearly 40 million years.

Professor Biggin heads up the University’s Determining Earth Evolution from Palaeomagnetism (DEEP) research group which brings together research expertise across geophysics and geology to develop palaeomagnetism as a tool for understanding deep Earth processes occurring across timescales of millions to billions of years.

Reference:
Mark W. Hounslow, Mathew Domeier, Andrew J. Biggin. Subduction flux modulates the geomagnetic polarity reversal rate. Tectonophysics, 2018; 742-743: 34 DOI: 10.1016/j.tecto.2018.05.018

Note: The above post is reprinted from materials provided by University of Liverpool.

Red tide fossils point to Jurassic sea flood

June 5, 2018

Dinoflagellate cysts — One of the dinoflagellate cysts, normally the cause of red tides in the sea, has been found in arid Australia. Credit: Carmine Wainman, University of Adelaide

Dinosaur-age fossilised remains of tiny organisms normally found in the sea have been discovered in inland, arid Australia — suggesting the area was, for a short time at least, inundated by sea water 40 million years before Australia’s large inland sea existed.

The fossils are the egg-like cysts of microorganisms known as dinoflagellates, best known for producing red tides or algal blooms that can turn the sea water blood red. The cysts rest on the sea floor before hatching new dinoflagellates.

Researchers at the University of Adelaide, in collaboration with geological consultancy MGPalaeo, discovered these microfossils in Jurassic rocks of south-western Queensland, near the town of Roma.

Described in the journal Palynology, the fossils have been dated to the late Jurassic period, 148 million years ago. This is a time when Australia was joined to Antarctica, and where dinosaurs roamed across ancient rivers, floodplains and swamps.

“We have plenty of evidence from the 110 million-year-old vast inland Eromanga Sea, which covered a large swathe of central, eastern Australia during the Cretaceous period (following on from the Jurassic),” says Dr Carmine Wainman, Postdoctoral Fellow in the University of Adelaide’s Australian School of Petroleum.

“We’ve seen the opalised fossils sold in Adelaide’s Rundle Mall, and the spectacular ancient marine reptiles on display in the South Australian Museum — all from the later Cretaceous period.

“However, this new microfossil evidence from the same region suggests there was a short-lived precursor to this sea 40 million years earlier.”

Dr Wainman believes these microfossils must have been brought inland by an incursion of sea water and then evolved quickly to adapt to the freshwater or brackish conditions as the sea waters slowly receded.

“There is no other feasible explanation for how they managed to reach the interior of the Australian continent when the ancient coastline was thousands of kilometres away,” Dr Wainman says.

“It was probably a result of rising sea levels during a time of greenhouse conditions before the establishment of the Eromanga Sea. With further investigations, we may find more of these microorganisms or even fossilised marine reptiles that uncover untold secrets about how this part of the world looked in the Jurassic.”

Reference:
Carmine C. Wainman, Daniel J. Mantle, Carey Hannaford, Peter J. McCabe. Possible freshwater dinoflagellate cysts and colonial algae from the Upper Jurassic strata of the Surat Basin, Australia. Palynology, 2018; 1 DOI: 10.1080/01916122.2018.1451785

Note: The above post is reprinted from materials provided by University of Adelaide.

New way to estimate magma beneath Yellowstone supervolcano

June 5, 2018

Washington State University researchers ‘spike’ a Yellowstone hot spring with deuterium, a stable isotope, to calculate water and heat flowing out of the springs and estimate how fast magma is recharging beneath the Yellowstone supervolcano. The material had no environmental impact and was done with a permit from the National Park Service. Credit: Washington State University

Researchers at Washington State University and the University of Idaho have found a new way to estimate how fast magma is recharging beneath the Yellowstone supervolcano. While their findings offer no help in predicting if the volcano will erupt, they can now get a better understanding of a key factor — a pool of basalt magma recharging the system — in how it works.

“It is the coal in the furnace that’s heating things up,” said Peter Larson, a professor in the Washington State University School of the Environment. “It’s heating up the boiler. The boiler is what explodes. This tells us what is heating the boiler.”

Some 640,000 years have passed since the volcano’s last major eruption. But it can be “super,” having produced one of the largest known blasts on Earth and spewing more than 2,000 times as much ash as Mount St. Helens did in 1980.

A major element in the volcano’s power is the explosive, silica-rich rhyolite that break’s through the Earth’s crust during an eruption. Larson and his colleagues focused on the plume of basalt magma heating the rhyolite from below.

“This gives us an idea of how much magma is recharging the volcano every year,” said Larson, whose findings appear in the latest issue of the journal Geosphere.

With funding from the National Science Foundation, the researchers “spiked” several hot springs in Yellowstone National Park with deuterium, a stable hydrogen isotope. The researchers used the length of time needed for deuterium concentrations to return to background levels and the temperature of the hot springs to calculate the amount of water and heat flowing out of the springs. Using deuterium for estimating heat flow is safe for the environment and has no visual impact to distract from the park visitors’ experience.

The team found that previous studies underestimated the amount of water coursing through the springs and the amount of heat leaving the springs. The data also allowed the team to estimate the amount of magma entering the supervolcano from the mantle.

The study also has implications for geothermal energy, helping inform how heat is transported to the earth’s surface from molten rock.

Reference:
Nicholas McMillan, Peter Larson, Jerry Fairley, Joseph Mulvaney-Norris, Cary Lindsey. Direct measurement of advective heat flux from several Yellowstone hot springs, Wyoming, USA. Geosphere, 2018; DOI: 10.1130/GES01598.1

Note: The above post is reprinted from materials provided by Washington State University.

Thank the moon for Earth’s lengthening day

June 5, 2018

Image of Earth taken by the Apollo 8 astronauts on Dec. 22, 1968 as they became the first humans to circumnavigate the moon. Credit: Courtesy of NASA

For anyone who has ever wished there were more hours in the day, geoscientists have some good news: Days on Earth are getting longer.

A new study that reconstructs the deep history of our planet’s relationship to the moon shows that 1.4 billion years ago, a day on Earth lasted just over 18 hours. This is at least in part because the moon was closer and changed the way Earth spun around its axis.

“As the moon moves away, the Earth is like a spinning figure skater who slows down as they stretch their arms out,” explains Stephen Meyers, professor of geoscience at the University of Wisconsin-Madison and co-author of the study published this week [June 4, 2018] in the Proceedings of the National Academy of Sciences.

It describes a tool, a statistical method, that links astronomical theory with geological observation (called astrochronology) to look back on Earth’s geologic past, reconstruct the history of the solar system and understand ancient climate change as captured in the rock record.

“One of our ambitions was to use astrochronology to tell time in the most distant past, to develop very ancient geological time scales,” Meyers says. “We want to be able to study rocks that are billions of years old in a way that is comparable to how we study modern geologic processes.”

Earth’s movement in space is influenced by the other astronomical bodies that exert force on it, like other planets and the moon. This helps determine variations in Earth’s rotation around and wobble on its axis, and in the orbit Earth traces around the sun.

These variations are collectively known as Milankovitch cycles and they determine where sunlight is distributed on Earth, which also means they determine Earth’s climate rhythms. Scientists like Meyers have observed this climate rhythm in the rock record, spanning hundreds of millions of years.

But going back further, on the scale of billions of years, has proved challenging because typical geologic means, like radioisotope dating, do not provide the precision needed to identify the cycles. It’s also complicated by lack of knowledge of the history of the moon, and by what is known as solar system chaos, a theory posed by Parisian astronomer Jacques Laskar in 1989.

The solar system has many moving parts, including the other planets orbiting the sun. Small, initial variations in these moving parts can propagate into big changes millions of years later; this is solar system chaos, and trying to account for it can be like trying to trace the butterfly effect in reverse.

Last year, Meyers and colleagues cracked the code on the chaotic solar system in a study of sediments from a 90 million-year-old rock formation that captured Earth’s climate cycles. Still, the further back in the rock record he and others have tried to go, the less reliable their conclusions.

For instance, the moon is currently moving away from Earth at a rate of 3.82 centimeters per year. Using this present day rate, scientists extrapolating back through time calculated that “beyond about 1.5 billion years ago, the moon would have been close enough that its gravitational interactions with the Earth would have ripped the moon apart,” Meyers explains. Yet, we know the moon is 4.5 billion years old.

So, Meyers sought a way to better account for just what our planetary neighbors were doing billions of years ago in order to understand the effect they had on Earth and its Milankovitch cycles. This was the problem he brought with him to a talk he gave at Columbia University’s Lamont-Doherty Earth Observatory while on sabbatical in 2016.

In the audience that day was Alberto Malinverno, Lamont Research Professor at Columbia. “I was sitting there when I said to myself, ‘I think I know how to do it! Let’s get together!'” says Malinverno, the other study co-author. “It was exciting because, in a way, you dream of this all the time; I was a solution looking for a problem.”

The two teamed up to combine a statistical method that Meyers developed in 2015 to deal with uncertainty across time — called TimeOpt — with astronomical theory, geologic data and a sophisticated statistical approach called Bayesian inversion that allows the researchers to get a better handle on the uncertainty of a study system.

They then tested the approach, which they call TimeOptMCMC, on two stratigraphic rock layers: the 1.4 billion-year-old Xiamaling Formation from Northern China and a 55 million-year-old record from Walvis Ridge, in the southern Atlantic Ocean.

With the approach, they could reliably assess from layers of rock in the geologic record variations in the direction of the axis of rotation of Earth and the shape of its orbit both in more recent time and in deep time, while also addressing uncertainty. They were also able to determine the length of day and the distance between Earth and the moon.

“In the future, we want to expand the work into different intervals of geologic time,” says Malinverno.

The study complements two other recent studies that rely on the rock record and Milankovitch cycles to better understand Earth’s history and behavior.

A research team at Lamont-Doherty used a rock formation in Arizona to confirm the remarkable regularity of Earth’s orbital fluctuations from nearly circular to more elliptical on a 405,000 year cycle. And another team in New Zealand, in collaboration with Meyers, looked at how changes in Earth’s orbit and rotation on its axis have affected cycles of evolution and extinction of marine organisms called graptoloids, going back 450 million years.

“The geologic record is an astronomical observatory for the early solar system,” says Meyers. “We are looking at its pulsing rhythm, preserved in the rock and the history of life.”

The study was funded by the National Science Foundation (EAR-1151438).

Reference:
Stephen R. Meyers, Alberto Malinverno. Proterozoic Milankovitch cycles and the history of the solar system. Proceedings of the National Academy of Sciences, 2018; 201717689 DOI: 10.1073/pnas.1717689115

Note: The above post is reprinted from materials provided by University of Wisconsin-Madison. Original written by Kelly April Tyrrell.

Scientists find pre-earthquake activity in central Alaska

June 5, 2018

Lakes in the roadless Minto Flats surround the Tanana River in this photo from July 2014. The ridge on the horizon leads down to the town of Nenana, Alaska. Seismic stations placed in this unique region detected some intriguing pre-earthquake activity. Credit: UAF Photo by Carl Tape

Earth scientists consistently look for a reliable way to forecast earthquakes. New research from University of Alaska Fairbanks Geophysical Institute professor Carl Tape may help in that endeavor, due to a unique set of circumstances.

“Our observations have recorded an unequivocally interesting sequence of events,” Tape said.

Tape and his colleagues found evidence for accelerating activity before a 2016 earthquake in a laterally moving fault zone in central Alaska. The activity included a phenomenon known as very low-frequency earthquakes, referring to the type of energy waves associated with it.

Typical earthquakes have two associated energy waves, called the P and S waves. Very low-frequency earthquakes do not have such signals. Instead, their waves occur on much lower frequencies.

“Most earthquakes start abruptly, but not always,” said Luciana Astiz, a program director in the National Science Foundation’s Division of Earth Sciences, which supported the research. “A fault zone in central Alaska monitored by new scientific instruments offers a look at a more complex process. This study reports the first observations of a slow process that transitions into an earthquake — something previously observed only in laboratory experiments. These new observations contribute toward understanding the physics of earthquakes.”

In 2015, Tape installed 13 seismic stations in the Minto Flats of central Alaska to capture the area’s fault activity. Nine days later, the instruments recorded a long-duration, very low-frequency process, normally only seen in deep subduction zones. This event showed a small amount of activity gathering, or nucleating, in a central area below the surface. It did not lead to an earthquake.

A second, similar event in 2016 led to a key observation. At Minto Flats, a magnitude 3.7 quake occurred at a depth of about 10.5 miles, not an unusual event in itself. However, the event was preceded by a 12-hour accelerating sequence of earthquakes and 22 seconds of distinct high- and low-frequency waves in a concentrated area.

Tape said that this kind of slow event transitioning into a rupture had previously only been seen in laboratory experiments.

“The rupture process started, then it found a patch of the fault that was ready to go, and that’s what people have not seen. It’s really exciting,” Tape said.

“The leap we make, and maybe the more controversial thing, is that this emergent long-period signal only seen on top of the fault is a low-frequency signal that can sometimes turn into an earthquake and sometimes not,” Tape said.

Tape and his colleagues may have seen this kind of activity before. In 2012, there was a similar small event recorded in central Alaska. At that time, a magnitude 8.6 earthquake took place under the Indian Ocean and its energy was felt around the world. Because of the magnitude of this event, the smaller activity from central Alaska was overshadowed. Whatever signal the Minto Flats site gave off could not be confirmed. However, it was intriguing enough to help justify putting sensors in the area.

“Never in my wildest dreams did I expect we’d see something like that again,” Tape said. “I assumed that the conditions that happened in 2012 were somehow unique and that huge surface waves led to this nucleation. Even though I proposed putting instruments on the area in a proposal, it was the last item I put on. I thought, “Maybe we’ll see something crazy out there.'”

By 2016, Tape had high-quality stations on top of the Minto Flat faults, around 18 miles from the main events, and no triggering earthquake to complicate the data.

“We are staring right at this process, and what it showed was that exactly during the tremor-like signal there is this emergent long-duration signal that hints at what’s driving this nucleation phase,” he said.

Geologists have been looking for something like this for a long time. So why hasn’t anyone seen it?

“I’m left saying ‘I don’t know,'” Tape said. “I’m going to assume everyone has been looking for something before the P wave forever. It leads me to believe there is something special about this fault zone.”

Minto Flats has a deep sedimentary basin, strike-slip faulting, active tectonics and deep earthquakes; it is an unusual site.

“In some ways, I wish there wasn’t anything special. I wish it was a global phenomenon that we discovered, but it’s not,” Tape said. “It appears there is something special about the conditions in Minto Flats.”

The results of the research will appear in the latest issue of the journal Nature Geoscience. The paper is titled “Earthquake Nucleation and Fault Slip Complexity in the Lower Crust of Central Alaska.”

The project was primarily funded by a National Science Foundation CAREER project that supported Tape and his student co-authors, Vipul Silwal and Kyle Smith.

Reference:
Carl Tape, Stephen Holtkamp, Vipul Silwal, Jessica Hawthorne, Yoshihiro Kaneko, Jean Paul Ampuero, Chen Ji, Natalia Ruppert, Kyle Smith, Michael E. West. Earthquake nucleation and fault slip complexity in the lower crust of central Alaska. Nature Geoscience, 2018; DOI: 10.1038/s41561-018-0144-2

Note: The above post is reprinted from materials provided by University of Alaska Fairbanks.

Earth’s first giant predators produced killer babies

June 2, 2018

This is an artistic representation of juvenile (foreground) and adult (background) Lyrarapax unguispinus hunting in the water column. Relative sizes are based on the smallest (length: 1.8 cm) and largest (length: 8 cm) known specimens of L. unguispinus. Credit: Science China Press

Some of the earliest predators that patrolled the oceans over 500 million years ago are also some of the largest animals to have lived at the time. However, a new fossil study led by Jianni Liu from the Northwest University of Xi’an in China, has shown that their tiny babies were also proficient killers.

The “creepy crawly” animal group known as the Arthropoda, which includes spiders, insects and crustaceans, has often been the inspiration behind many science fiction monsters, largely due to their scary-looking appendages. Some of the oldest and most primitive arthropod species belong to a group called the Radiodonta (“radiating teeth”), which were armed with large, spiny raptorial (or grasping) appendages at the front of the head and a circular mouth adorned with tooth-like serrations. These animals, including the famous Anomalocaris, are considered the giant apex predators of their time, reaching lengths of over one metre.

Until now, virtually nothing was known about the juveniles of radiodontans and their feeding habits. The discovery of an exceptionally-preserved juvenile of a species called Lyrarapax unguispinus from the early Cambrian (518 million-year-old) Chengjiang biota of China has shed new light on this iconic group of fossil arthropods.

At only 18mm in total body length, this almost complete specimen represents the smallest radiodontan ever found. To the surprise of the research team, its anatomy is extraordinarily well developed–especially the spiny grasping appendages–giving it the appearance of a miniaturised adult. This indicates that Lyrarapax unguispinus was a well-equipped predator at an early developmental stage, similar to modern arthropods such as praying mantises, mantis shrimps, and arachnids. This discovery confirms that raptorial feeding habits in juveniles appeared early on in the evolutionary history of arthropods.

This fossil find also has important implications for the rapid evolution of the first animals over half-a-billion years ago – an event referred to colloquially as the Cambrian ‘Explosion’. It is hypothesised that predation was a major driver of this evolutionary event, with predators placing selective pressures on animal communities, forcing prey species to adapt and evolve or face extinction.The predatory lifestyles of juvenile radiodontans adds further complexity to Cambrian marine food webs by placing additional pressures on small prey during this evolutionary ‘arms race’.

Reference:
Liu, J. N., Lerosey-Aubril, R., Steiner, M., Dunlop, J. A., Shu, D. G. & Paterson, J. R. 2018.Origin of raptorial feeding in juvenile euarthropods revealed by a Cambrian radiodontan. National Science Review. DOI: 10.1093/nsr/nwy057

Note: The above post is reprinted from materials provided by Science China Press.

World’s oldest lizard fossil discovered

May 30, 2018

An international team of paleontologists, which includes the University of Bristol, have identified the world’s oldest lizard, providing key insight into the evolution of modern lizards and snakes.

The 240-million-year-old fossil, Megachirella wachtleri, is the most ancient ancestor of all modern lizards and snakes, known as squamates, the new study, published today in the journal Nature, shows.

The fossil, along with data from both living and extinct reptiles — which involved anatomical data drawn from CT scans and DNA — suggests the origin of squamates is even older, taking place in the late Permian period, more than 250 million years ago.

Tiago Simões, lead author and PhD student from the University of Alberta in Canada, said: “The specimen is 75 million years older than what we thought were the oldest fossil lizards in the entire world and provides valuable information for understanding the evolution of both living and extinct squamates.”

Currently, there are 10,000 species of lizards and snakes around the world — twice as many different species as mammals. Despite this modern diversity, scientists did not know much about the early stages of their evolution.

Tiago Simões added: “It is extraordinary when you realize you are answering long-standing questions about the origin of one of the largest groups of vertebrates on Earth.”

Co-author, Dr Michael Caldwell, also from the University of Alberta, added: “Fossils are our only accurate window into the ancient past. Our new understanding of Megachirella is but a point in ancient time, but it tells us things about the evolution of lizards that we simply cannot learn from any of the 9000 or so species of lizards and snakes alive today.”

Originally found in the early 2000s in the Dolomites Mountains of Northern Italy, researchers considered it an enigmatic lizard-like reptile but could not reach conclusive placement, and it ramained nearly unnoticed by the international community.

In order to better understand both the anatomy of Megachirella and the earliest evolution of lizards and snakes the authors assembled the largest reptile dataset ever created.

The authors combined it with several new anatomical information from Megachirella obtained from high-resolution CT scans.

All this new information was analysed using state of the art methods to assess relationships across species, revealing that the once enigmatic reptile was actually the oldest known squamate.

Co-author Dr Randall Nydam of the Midwestern University in Arizona, said: “At first I did not think Megachirella was a true lizard, but the empirical evidence uncovered in this study is substantial and can lead to no other conclusion.”

Co-author Dr Massimo Bernardi from MUSE — Science Museum, Italy and University of Bristol’s School of Earth Sciences, added: “This is the story of the re-discovery of a specimen and highlights the importance of preserving naturalistic specimens in well maintained, publicly accessible collections.

“New observations, that could arise from the use of new techniques — as for the mCT data we have obtained here, could provide a completely new understanding even of long-known specimens.”

Reference:
Tiago R. Simões, Michael W. Caldwell, Mateusz Tałanda, Massimo Bernardi, Alessandro Palci, Oksana Vernygora, Federico Bernardini, Lucia Mancini, Randall L. Nydam. The origin of squamates revealed by a Middle Triassic lizard from the Italian Alps. Nature, 2018; 557 (7707): 706 DOI: 10.1038/s41586-018-0093-3

Note: The above post is reprinted from materials provided by University of Bristol.

Life recovered rapidly at impact site of dino-killing asteroid

May 30, 2018

An asteroid impact 66 million years ago wiped out life across the planet, but microorganisms quickly rebounded. New research has found evidence for a diverse array of plankton and other organisms inhabiting the crater only a few years after the extinction-causing impact. The three hair-covered forms (left) represent species of plankton found inside the crater. The geometric form (bottom left) is a species of algae. Small organisms like these moved into the crater so quickly that bones from animals that were killed by the impact, such as the mosasaur pictured here, may have still been visible. Credit: Original art by John Maisano, University of Texas Jackson School of Geosciences.

About 66 million years ago, an asteroid smashed into Earth, triggering a mass extinction that ended the reign of the dinosaurs and snuffed out 75 percent of life.

Although the asteroid killed off species, new research led by The University of Texas at Austin has found that the crater it left behind was home to sea life less than a decade after impact, and it contained a thriving ecosystem within 30,000 years — a much quicker recovery than other sites around the globe.

Scientists were surprised by the findings, which undermine a theory that recovery at sites closest to the crater is the slowest due to environmental contaminants — such as toxic metals — released by the impact. Instead, the evidence suggests that recovery around the world was influenced primarily by local factors, a finding that could have implications for environments rocked by climate change today.

“We found life in the crater within a few years of impact, which is really fast, surprisingly fast,” said Chris Lowery, a postdoctoral researcher at the University of Texas Institute for Geophysics (UTIG) who led the research. “It shows that there’s not a lot of predictability of recovery in general.”

The research was published May 30 in the journal Nature. UTIG research scientists Gail Christeson and Sean Gulick and postdoctoral researcher Cornelia Rasmussen are co-authors on the paper, along with a team of international scientists. UTIG is a research unit of the Jackson School of Geosciences.

The evidence for life comes primarily in the form of microfossils — the remains of unicellular organisms such as algae and plankton — as well as the burrows of larger organisms discovered in a rock extracted from the crater during recent scientific drilling conducted jointly by the International Ocean Discovery Program and International Continental Drilling Program.

The tiny fossils are hard evidence that organisms inhabited the crater, but also a general indicator about habitability in the environment years after impact. The swift recovery suggests that other life forms aside from the microscopic were living in the crater shortly after impact.

“Microfossils let you get at this complete community picture of what’s going on,” Lowery said. “You get a chunk of rock and there’s thousands of microfossils there, so we can look at changes in the population with a really high degree of confidence … and we can use that as kind of a proxy for the larger scale organisms.”

The scientists found the first evidence for the appearance of life two to three years after impact. The evidence included burrows made by small shrimp or worms. By 30,000 years after impact, a thriving ecosystem was present in the crater, with blooming phytoplankton (microscopic plants) supporting a diverse community of organisms in the surface waters and on the seafloor. In contrast, other areas around the world, including the North Atlantic and other areas of the Gulf of Mexico, took up to 300,000 years to recover in a similar manner.

The core containing the fossil evidence was extracted from the crater during a 2016 expedition co-led by the Jackson School. In this study, scientists zeroed in on a unique core section that captures the post-impact seafloor in unprecedented detail. Whereas core samples from other parts of the ocean hold only millimeters of material deposited in the moments after impact, the section from the crater used in this study contains more than 130 meters of such material, the upper 30 inches of which settled out slowly from the turbid water. This material provides a record that captures the seafloor environment days to years after the impact.

“You can see layering in this core, while in others, they’re generally mixed, meaning that the record of fossils and materials is all churned up, and you can’t resolve tiny time intervals,” said co-author Timothy Bralower, a micropaleontology professor at Pennsylvania State University. “We have a fossil record here where we’re able to resolve daily, weekly, monthly, yearly changes.”

Ellen Thomas, a senior research scientist in geology and geophysics at Yale University who was not part of the study, said that although she thinks the paper makes a strong case for a speedy recovery, she expects that the larger scientific community will be interested in digging into the data for themselves.

“In my opinion, we will see considerable debate on the character, age, sedimentation rate and microfossil content … especially of the speculation that burrowing animals may have returned within years of the impact,” Thomas said.

The relatively rapid rebound of life in the crater suggests that although the asteroid caused the extinction, it didn’t hamper recovery. The scientists point to local factors, from water circulation to interactions between organisms and the availability of ecological niches, as having the most influence on a particular ecosystem’s recovery rate.

The findings indicate that recovery after a global catastrophe could be a local affair.

The International Ocean Discovery Program, the International Continental Drilling Program, the National Science Foundation and NASA funded the research.

Reference:
Christopher M. Lowery, Timothy J. Bralower, Jeremy D. Owens, Francisco J. Rodríguez-Tovar, Heather Jones, Jan Smit, Michael T. Whalen, Phillipe Claeys, Kenneth Farley, Sean P. S. Gulick, Joanna V. Morgan, Sophie Green, Elise Chenot, Gail L. Christeson, Charles S. Cockell, Marco J. L. Coolen, Ludovic Ferrière, Catalina Gebhardt, Kazuhisa Goto, David A. Kring, Johanna Lofi, Rubén Ocampo-Torres, Ligia Perez-Cruz, Annemarie E. Pickersgill, Michael H. Poelchau, Auriol S. P. Rae, Cornelia Rasmussen, Mario Rebolledo-Vieyra, Ulrich Riller, Honami Sato, Sonia M. Tikoo, Naotaka Tomioka, Jaime Urrutia-Fucugauchi, Johan Vellekoop, Axel Wittmann, Long Xiao, Kosei E. Yamaguchi, William Zylberman. Rapid recovery of life at ground zero of the end-Cretaceous mass extinction. Nature, 2018; DOI: 10.1038/s41586-018-0163-6

Note: The above post is reprinted from materials provided by University of Texas at Austin.

The smallest biggest theropod dinosaur

May 30, 2018

Spinosaurus is the longest, and among the largest predatory dinosaurs, and possesses many adaptations for a semiaquatic lifestyle. A tiny claw phalanx of the foot, discovered in Cretaceous-aged sandstones of the Sahara, shows a peculiar shape compatible with an early juvenile Spinosaurus. As reported in PeerJ — the Journal of Life & Environmental Sciences, the fossil is from the smallest known individual of this giant, sail-backed theropod. The findings suggest the small specimen retains the same locomotor adaptations as the large version — such as traversing soft substrates or paddling — during the entire lifespan.

Collected in Morocco in 1999, a 21 mm-long pedal ungual phalanx (a phalanx supporting a claw of the foot) remained unnoticed in the Paleontological Collection of the Natural History Museum of Milan, until the recent discovery (2014) of a new partial skeleton of Spinosaurus aegyptiacus, that preserves an almost complete right foot with peculiar morphology in the phalanges.

The striking similarities with the claw phalanges of the foot of Spinosaurus allowed palaeontologists Simone Maganuco and Cristiano Dal Sasso to identify the tiny bone to a very small and young specimen of the sail-backed Spinosaurus, the smallest individual reported up to today. “Besides the rarity of the fossils belonging to juvenile theropod dinosaurs, and the rarity of Spinosaurus bones, this finding is even more remarkable if we consider the dramatic size attained by some large specimens of Spinosaurus, which are possibly the longest, and among the largest predatory dinosaurs ever found”- says Maganuco.

Assuming the juveniles looked like smaller versions of the adults, the 21 mm-long claw phalanx from this small specimen would pertain to an early juvenile individual, 1.78 m-long, only just a little bit longer than the estimated length of the sole head of the largest adult Spinosaurus known to date, which is also housed at the Natural History Museum of Milan.

According to recent studies, the broader than deep unguals in Spinosaurus with their flat plantar surface are reminiscent of the flattened pedal shape of shorebirds that do not perch, and the whole foot may have been adapted to traversing soft substrates or webbed for paddling. “This find indicates that in Spinosaurus the foot of early juveniles had the same locomotor adaptations observed in large individuals, that were probably achieved early in ontogeny and retained for the entire lifespan,” remarks co-author Cristiano Dal Sasso.

Reference:
Simone Maganuco, Cristiano Dal Sasso. The smallest biggest theropod dinosaur: a tiny pedal ungual of a juvenile Spinosaurus from the Cretaceous of Morocco. PeerJ, 2018; 6: e4785 DOI: 10.7717/peerj.4785

Note: The above post is reprinted from materials provided by PeerJ.

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