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New Egyptian dinosaur reveals ancient link between Africa and Europe

Skeletal reconstruction of the new titanosaurian dinosaur Mansourasaurus shahinae from the Late Cretaceous of the Dakhla Oasis, Egypt.
Skeletal reconstruction of the new titanosaurian dinosaur Mansourasaurus shahinae from the Late Cretaceous of the Dakhla Oasis, Egypt. Bones shown in color are those that are preserved in the original fossil; other bones are based on those of closely related dinosaurs. Credit: Andrew McAfee, Carnegie Museum of Natural History

When it comes to the final days of the dinosaurs, Africa is something of a blank page. Fossils found in Africa from the Late Cretaceous, the time period from 100 to 66 million years ago, are few and far between. That means that the course of dinosaur evolution in Africa has largely remained a mystery. But in the Sahara Desert of Egypt, scientists have discovered a new species of dinosaur that helps fill in those gaps: Mansourasaurus shahinae, a school-bus-length, long-necked plant-eater with bony plates embedded in its skin.

The fossilized remains of Mansourasaurus were unearthed by an expedition undertaken by the Mansoura University Vertebrate Paleontology (MUVP) initiative, an effort led by Dr. Hesham Sallam of the Department of Geology at Mansoura University in Mansoura, Egypt. Sallam is the lead author of the paper published today in the journal Nature Ecology and Evolution that names the new species. The field team included several of his students, many of whom — Ms. Iman El-Dawoudi, Ms. Sanaa El-Sayed, and Mrs. Sara Saber — also participated in the study of the new dinosaur. The creature’s name honors both Mansoura University and Ms. Mona Shahin for her integral role in developing the MUVP. According to Sallam, “The discovery and extraction of Mansourasaurus was such an amazing experience for the MUVP team. It was thrilling for my students to uncover bone after bone, as each new element we recovered helped to reveal who this giant dinosaur was.”

“Mansourasaurus shahinae is a key new dinosaur species, and a critical discovery for Egyptian and African paleontology,” says Dr. Eric Gorscak, a postdoctoral research scientist at The Field Museum and a contributing author on the study. Gorscak, who began work on the project as a doctoral student at Ohio University, where his research focused on African dinosaurs, adds, “Africa remains a giant question mark in terms of land-dwelling animals at the end of the Age of Dinosaurs. Mansourasaurus helps us address longstanding questions about Africa’s fossil record and paleobiology — what animals were living there, and to what other species were these animals most closely related?”

Late Cretaceous dinosaur fossils in Africa are hard to come by — much of the land where their fossils might be found is covered in lush vegetation, rather than the exposed rock of dinosaur treasure troves such as those in the Rocky Mountain region, the Gobi Desert, or Patagonia. The lack of a Late Cretaceous fossil record in Africa is frustrating for paleontologists since, at that time, the continents were undergoing massive geological and geographic changes.

During the earlier years of the dinosaurs, throughout much of the Triassic and Jurassic periods, all the continents were joined together as the supercontinent of Pangaea. During the Cretaceous Period, however, the continents began splitting apart and shifting towards the configuration we see today. Historically, it hasn’t been clear how well-connected Africa was to other Southern Hemisphere landmasses and Europe during this time — to what degree Africa’s animals may have been cut off from their neighbors and evolving on their own separate tracks. Mansourasaurus, as one of the few African dinosaurs known from this time period, helps to answer that question. By analyzing features of its bones, Sallam and his team determined that Mansourasaurus is more closely related to dinosaurs from Europe and Asia than it is to those found farther south in Africa or in South America. This, in turn, shows that at least some dinosaurs could move between Africa and Europe near the end of these animals’ reign. “Africa’s last dinosaurs weren’t completely isolated, contrary to what some have proposed in the past,” says Gorscak. “There were still connections to Europe.”

Mansourasaurus belongs to the Titanosauria, a group of sauropods (long-necked plant-eating dinosaurs) that were common throughout much of the world during the Cretaceous. Titanosaurs are famous for including the largest land animals known to science, such as Argentinosaurus, Dreadnoughtus, and Patagotitan. Mansourasaurus, however, was moderate-sized for a titanosaur, roughly the weight of an African bull elephant. Its skeleton is important in being the most complete dinosaur specimen so far discovered from the end of the Cretaceous in Africa, preserving parts of the skull, the lower jaw, neck and back vertebrae, ribs, most of the shoulder and forelimb, part of the hind foot, and pieces of dermal plates. Says study coauthor and dinosaur paleontologist Dr. Matt Lamanna of Carnegie Museum of Natural History, “When I first saw pics of the fossils, my jaw hit the floor. This was the Holy Grail — a well-preserved dinosaur from the end of the Age of Dinosaurs in Africa — that we paleontologists had been searching for for a long, long time.”

Also contributing to the Mansourasaurus research were experts on African paleontology from other institutions in Egypt and the US. MUVP student Iman El-Dawoudi played a particularly important role in the analysis of the new titanosaur, making numerous observations on its skeleton. “The combined effort of multiple institutions across the globe, not to mention the absolutely key role played by students on the project from the field, to the laboratory, to the final analysis and writeup of the results, exemplifies the collaborative nature of expeditionary sciences today,” notes Dr. Patrick O’Connor, study coauthor and professor of anatomy at the Ohio University Heritage College of Osteopathic Medicine.

Funding for the Mansourasaurus study was provided by grants from Mansoura University, the Jurassic Foundation, the Leakey Foundation, the National Geographic Society/Waitt Foundation, and the National Science Foundation (NSF).

“The discovery of rare fossils like this sauropod dinosaur helps us understand how creatures moved across continents, and gives us a greater understanding of the evolutionary history of organisms in this region,” says Dena Smith, a program director in NSF’s Division of Earth Sciences, which partially funded the laboratory portion of the research.

Scientific discoveries are often compared to finding the last missing puzzle piece to complete a picture; Gorscak says that since so little is known about African dinosaurs, Mansourasaurus is better likened to an earlier step in the puzzle-solving process. “It’s like finding an edge piece that you use to help figure out what the picture is, that you can build from. Maybe even a corner piece.”

“What’s exciting is that our team is just getting started. Now that we have a group of well-trained vertebrate paleontologists here in Egypt, with easy access to important fossil sites, we expect the pace of discovery to accelerate in the years to come,” says Sallam.

Reference:
Hesham M. Sallam, Eric Gorscak, Patrick M. O’Connor, Iman A. El-Dawoudi, Sanaa El-Sayed, Sara Saber, Mahmoud A. Kora, Joseph J. W. Sertich, Erik R. Seiffert, Matthew C. Lamanna. New Egyptian sauropod reveals Late Cretaceous dinosaur dispersal between Europe and Africa. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-017-0455-5

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

Mansourasaurus- A story from the land of Pharaoh and Dinosaurs

Mansourasaurus, New Egyptian dinosaur
Mansourasaurus, New Egyptian dinosaur

The story of the Mansourasaurus discovery began in December of 2013, when I received an invitation to give a talk about vertebrate paleontology at New Valley University in Kharga Oasis in southern Egypt. To get there I drove 12 hours with my graduate students from Mansoura University, Sanaa El-Sayed and Iman El-Dawoudi, who had just graduated and were eager to reach out to other Egyptian students about fossil vertebrates. On the way there we also picked up my third student, Sara Saber, from Assiut University. After the talk, we drove out to quickly have a closer look at the dinosaur-bearing rock exposures around Dakhla Oasis that I had been working in since 2008, with American colleagues from Ohio University, the University of Southern California, and the Denver Museum of Nature and Science. Our project aims to fill a ~30 million year gap in the Late Cretaceous fossil record of Africa, from which very few fossils of land-living vertebrates are known.

As the sun was going down, I noticed a new road that could give us a view of some unexplored exposures, so the next morning we drove all the way to its end and found a gravel quarry. We had only half an hour to look at the rocks before the long drive back to Mansoura. Sara and I walked in the same direction, while the others headed off in different directions to cover as much ground as possible. Only a few minutes later, I looked over my shoulder to see that Sara was brushing something, which I assumed was probably a rock. I kept walking and a few minutes later my cell phone rang. It was Sara. I picked up the phone to hear her excitedly telling me to please come back, because there were fossil bones all over the place. I quickly returned to find that the area was indeed full of bones… the remains of an associated partial skeleton of a sauropod dinosaur. I noticed my footprints all over the site, and joked with Sara, saying “by the way, I saw it first but left it for you as a test.” She replied quickly, saying “no, professor, you stepped all over the bones!,” and we had a good laugh. It was one of those wonderful moments in paleontology when you know that something really important has just been discovered.

I knew that we needed at least two weeks of fieldwork to properly excavate the skeleton, so we made the difficult decision to come back later and better prepared. Leaving such an important discovery behind made everyone incredibly anxious, because all of the bulldozers moving through the area could destroy the fossils in an instant. After two long months of preparation, we returned to the site with Sanaa, Iman, Sara, and two of my other colleagues, Mai El-Amir and Farahat Ibrahim. The excavation was difficult as the area is extremely hot, and we were hit with sandstorms and even pouring rain, but our enthusiasm kept us going, as we knew that we were writing a new chapter in the history of Egyptian vertebrate paleontology. Every evening, we went to the highest point in the area to get access to the Internet to learn more about dinosaur anatomy. On the third day we found the most diagnostic bone, the left dentary, from which it was clear that the lower jaw of this sauropod had a pronounced ‘chin.’ We were in close contact with our friends and colleagues in Egypt and the U.S.A., who were following the action daily. As time passed it became clear that we had skull bones, much of the shoulder girdle and forelimb, multiple vertebrae and ribs, part of the foot, and pieces of several dermal plates – more than was known for any dinosaur of this age from the entire African continent. While chatting with my American colleague Joe Sertich, he suggested the name Mansourasaurus, and it stuck.

We ended up working at the site for three weeks, and by the time we were finished we had made 19 plaster jackets and collected loads of isolated bone fragments. When we returned to Mansoura, we brought the jackets to be CT scanned at the university hospital. Never having seen plaster jackets in the hospital before, some of the staff stopped us and asked what we were pushing around on a gurney. I told them it was a dinosaur. They were astonished! One man asked if it was sick… to which I replied that it had been dead for at least 75 million years!

As time went on we would regularly meet up with our American colleagues over Skype, particularly the sauropod experts Eric Gorscak of Ohio University and later The Field Museum, Matt Lamanna of the Carnegie Museum, and Patrick O’Connor of Ohio University. Slowly the picture started to come together of just what we were dealing with. I think most of us initially expected Mansourasaurus to have been a member of a very ancient African lineage, given that continent’s hypothesized isolation during the Cretaceous, but it turned out that its closest affinities were instead with European sauropods, providing some of the first compelling evidence for the movement of dinosaurs between Africa and Europe in the later part of the Cretaceous. A find like this shows how little we still know about the Late Cretaceous of Africa, and has motivated us all to keep up the search for new fossils in Egypt.

Note: The above post is reprinted from materials provided by Nature. The original article was written by Hesham Sallam.

Researchers pose revolutionary theory on horse evolution

Silhouettes show Mesohippus primigenium, an early ancestor of the modern horse that lived 40 million years ago and was previously believed to have three toes, and the modern horse
Silhouettes show Mesohippus primigenium, an early ancestor of the modern horse that lived 40 million years ago and was previously believed to have three toes, and the modern horse. Photographs of both animals’ hand bones appear alongside renderings of the researchers’ proposed digit identities. The researchers argue that missing digits one and five are partially expressed on the surfaces of the side toes (shown in red/blue). While the horse is described as being monodactyl, with only one complete digit, the researchers demonstrate that digits two and four are expressed as the splint bones and frog (padding of the foot), as shown in yellow/green. Missing digits one and five are expressed as ridges on the splint bones and as the hoof cartilages, as shown in the lower red/blue areas. Credit: NYITCOM

Scientists have long wondered how the horse evolved from an ancestor with five toes to the animal we know today. While it is largely believed that horses simply evolved with fewer digits, researchers at New York Institute of Technology College of Osteopathic Medicine (NYITCOM) pose a new theory that suggests remnants of all five toes are still present within the hooves of the horse.

Humans and horses are descendants of a common ancestor with five digits. As horses evolved to live on open grassland their anatomy required a more compact design to enable movement across the hard plains. Until now, scientists believed horses adapted to these conditions by gradually evolving with fewer digits than its five-toed ancestor, with the first horse retaining only four digits, its later descendant reduced to three, and today’s horse retaining just the central digit known as the metacarpal, the long bone above the hoof.

For the first time, as published in the January 24 issue of Royal Society Open Science, NYITCOM researcher, Nikos Solounias, Ph.D., paleontologist and anatomy professor, and a team of researchers propose that the reduction in the number of digits is not a matter of simple attrition; instead, they believe that all five digits have merged to form the compacted forelimbs with hooves that we know today.

Currently, scientists accept that splints, small bones found along the outer sides of the metacarpal in modern horses, are partially formed remnants of second and fourth digits. Tapering mid-way down the metacarpal, these fragments were inherited from an earlier ancestor, but ceased to develop into fully formed digits in modern horses. While the NYITCOM researchers note that this explanation of the second and fourth digits is viable, they argue that it is incomplete and fails to account for the animal’s first and fifth digits. Arguing that the horse is not truly monodactyl, that is, one-toed, these researchers contend that fragments of the “missing” digits can be found in the form of ridges on the backside of the splints. According to the researchers, this demonstrates that the first and fifth digits were not simply lost to evolution, but attached to their neighboring second and fourth digits.

“With a distinct surface from the metacarpal, we know the splints on today’s horses to be the remnants of the second and fourth digits,” said Solounias. “However, these partially formed digits also appear to contain their own elevated surfaces which hold additional evolutionary clues. We find these ridges, located on the posterior of each splint, to be the partially formed remains of the first and fifth digits, which were once connected to the cartilages of the hoof.”

Solounias first considered this theory in 1999 while studying fossil evidence from an eight-million-year-old horse known as Hipparion primigenium. The famous Laetoli footprints in Tanzania demonstrate Hipparion walked alongside early humans, and was believed to have had three digits. However, Solounias noticed that the bottom surface of Hipparion’s fossilized forelimb appeared to be divided in five sections, as though small toes had bonded together. After further studying images of the Laetoli footprints, he confirmed his finding in several of the impressions, and considered that Hipparion not only had five compacted toes, but likely passed this trait on to its descendants.

“Interestingly, we not only find hints of the missing digits on the modern horse, but also its ancestors, such as Hipparion and Mesohippus, two species believed to have three toes,” said Solounias.

Melinda Danowitz, D.O., a recent NYITCOM graduate and Solounias’ co-investigator in the study added, “While the horse’s lineage is classically described as having evolved from four to three toes, and eventually one single toe, we show that its extinct ancestors exhibit the reduced toes both at the wrist and at the hoof. These findings show that today’s horse is not truly monodactyl, and earlier ancestors were not in fact tridactyl or tetradactyl, that is, three-toed or four-toed.”

The researchers have also discovered neurovascular evidence in support of the five-digit theory, with dissections of modern equine fetus forelimbs revealing a greater number of arteries and nerves than would be expected in a single digit.

“If today’s horse does indeed have one digit per forelimb, we would expect each forelimb to have a total of two veins, two arteries, and two nerve bundles,” said Danowitz. “However, our dissections found between five and seven neurovascular bundles per forelimb, suggesting that additional toes begin to develop, but do not become fully differentiated.”

Reference:
Nikos Solounias, Melinda Danowitz, Elizabeth Stachtiaris, Abhilasha Khurana, Marwan Araim, Marc Sayegh, Jessica Natale. The evolution and anatomy of the horse manus with an emphasis on digit reduction. Royal Society Open Science, 2018; 5 (1): 171782 DOI: 10.1098/rsos.171782

Note: The above post is reprinted from materials provided by New York Institute of Technology.

The eleventh Archaeopteryx “Geologically oldest fossil”

Archaeopteryx
The geologically oldest, but most recently discovered specimen of Archaeopteryx. Credit: O. Rauhut, LMU

Researchers from Ludwig-Maximilians-Universitaet (LMU) in Munich report the first description of the geologically oldest fossil securely attributable to the genus Archaeopteryx, and provide a new diagnostic key for differentiating bird-like dinosaurs from their closest relatives.

Some 150 million years ago in what is now Northern Bavaria, Archaeopteryx — the oldest bird species yet discovered — inhabited a subtropical environment characterized by reef islands and lagoons set in a shallow sea that was part of the primordial Mediterranean. All the specimens of Archaeopteryx so far recovered were found in the valley of the Altmühl River, in geological settings that represent this habitat — the Jurassic Solnhofen Archipelago. The latest find was made there in 2010, and this new specimen has now been analyzed by a team of researchers led by LMU paleontologist Oliver Rauhut, a professor in the Department of Earth and Environmental Sciences who is also affiliated with the Bavarian State Collections for Paleontology and Geology in Munich. Stratigraphic analysis of the find locality reveals that the fossil is the oldest known representative of the genus Archaeopteryx.

“Specimens of Archaeopteryx are now known from three distinct rock units, which together cover a period of approximately 1 million years,” Rauhut explains. Notably, the oldest example exhibits features that were so far not known from the other specimens. “Among other things, they reveal that Archaeopteryx was very similar to advanced predatory dinosaurs in many respects,” says Rauhut. Moreover, in the new study, he and his colleagues provide a diagnosis that allows to reliably distinguish Archaeopteryx from its closest relatives, both non-avialan theropod dinosaurs and basal birds. This key will be very valuable, as a whole series of bird-like predatory dinosaurs has been described in recent years, mainly from China, which has greatly complicated the taxonomical classification of the group.

The new specimen is the 12th fossil to be attributed to the genus. However, in a study published in the online journal BMC Evolutionary Biology last year, Rauhut’s group reported that the first of these to come to light — the so-called Haarlem specimen discovered in 1861 — does not actually belong to the group. This result thus reduces the number of Archaeopteryx fossils to 11, although some doubts remain concerning the assignment of two of these. This underlines the necessity for a diagnosis to clearly identify Archaeopteryx.

Moreover, the investigation of the 11th specimen demonstrates that the known specimens span a remarkable range of anatomical variation. Potential explanations for the broad spectrum of variation extend from intraspecific developmental polymorphism to evolutionary differentiation, i.e., the possibility that the fossil material so far recovered represents more than one species. “The high degree of variation in the teeth is particularly striking — none of the specimens shows the same pattern of dentition as any other, which could reflect differences in diet,” Rauhut points out. “This is very reminiscent of the famous case of Darwin’s finches on the Galapagos, which show remarkable variation in their beak shapes. It is even conceivable that this primeval bird genus might, in a similar fashion, have diversified into several specialized forms on the islands of the Solnhofener Archipelago. In that case, the Archaeopteryx fossils could represent a species flock, a Jurassic analog of Darwin’s finches.”

Reference:
Oliver W.M. Rauhut, Christian Foth, Helmut Tischlinger. The oldest Archaeopteryx (Theropoda: Avialiae): a new specimen from the Kimmeridgian/Tithonian boundary of Schamhaupten, Bavaria. PeerJ, 2018; 6: e4191 DOI: 10.7717/peerj.4191

Note: The above post is reprinted from materials provided by Ludwig-Maximilians-Universität München.

Scientists discover oldest known modern human fossil outside of Africa

This is the left hemi-maxilla with teeth.
This is the left hemi-maxilla with teeth. Credit: Rolf Quam

A large international research team, led by Israel Hershkovitz from Tel Aviv University and including Rolf Quam from Binghamton University, State University of New York, has discovered the earliest modern human fossil ever found outside of Africa. The finding suggests that modern humans left the continent at least 50,000 years earlier than previously thought.

“Misliya is an exciting discovery,” says Rolf Quam, Binghamton University anthropology professor and a coauthor of the study. “It provides the clearest evidence yet that our ancestors first migrated out of Africa much earlier than we previously believed. It also means that modern humans were potentially meeting and interacting during a longer period of time with other archaic human groups, providing more opportunity for cultural and biological exchanges.”

The fossil, an upper jawbone with several teeth, was found at a site called Misliya Cave in Israel, one of several prehistoric cave sites located on Mount Carmel. Several dating techniques applied to archaeological materials and the fossil itself suggest the jawbone is between 175,000-200,000 years old, pushing back the modern human migration out of Africa by at least 50,000 years.

Researchers analyzed the fossil remains relying on microCT scans and 3D virtual models and compared it with other hominin fossils from Africa, Europe and Asia.

“While all of the anatomical details in the Misliya fossil are fully consistent with modern humans, some features are also found in Neandertals and other human groups,” said Quam, associate professor of anthropology at Binghamton. “One of the challenges in this study was identifying features in Misliya that are found only in modern humans. These are the features that provide the clearest signal of what species the Misliya fossil represents.”

The archaeological evidence reveals that the inhabitants of Misliya Cave were capable hunters of large game species, controlled the production of fire and were associated with an Early Middle Paleolithic stone tool kit, similar to that found with the earliest modern humans in Africa.

While older fossils of modern humans have been found in Africa, the timing and routes of modern human migration out of Africa are key issues for understanding the evolution of our own species, said the researchers. The region of the Middle East represents a major corridor for hominin migrations during the Pleistocene and has been occupied at different times by both modern humans and Neandertals.

This new discovery opens the door to demographic replacement or genetic admixture with local populations earlier than previously thought, said Quam. Indeed, the evidence from Misliya is consistent with recent suggestions based on ancient DNA for an earlier migration, prior to 220,000 years ago, of modern humans out of Africa. Several recent archaeological and fossil discoveries in Asia are also pushing back the first appearance of modern humans in the region and, by implication, the migration out of Africa.

Reference:
Israel Hershkovitz, Gerhard W. Weber, Rolf Quam, Mathieu Duval, Rainer Grün, Leslie Kinsley, Avner Ayalon, Miryam Bar-Matthews, Helene Valladas, Norbert Mercier, Juan Luis Arsuaga, María Martinón-Torres, José María Bermúdez de Castro, Cinzia Fornai, Laura Martín-Francés, Rachel Sarig, Hila May, Viktoria A. Krenn, Viviane Slon, Laura Rodríguez, Rebeca García, Carlos Lorenzo, Jose Miguel Carretero, Amos Frumkin, Ruth Shahack-Gross, Daniella E. Bar-Yosef Mayer, Yaming Cui, Xinzhi Wu, Natan Peled, Iris Groman-Yaroslavski, Lior Weissbrod, Reuven Yeshurun, Alexander Tsatskin, Yossi Zaidner, Mina Weinstein-Evron. The earliest modern humans outside Africa. Science, 26 Jan 2018 456-459 DOI: 10.1126/science.aap8369

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

Primordial oceans had oxygen 250 million years before the atmosphere

Ocean.
Ocean. Credit: Copyright Michele Hogan

Research by a University of Minnesota Duluth (UMD) graduate student Mojtaba Fakhraee and Associate Professor Sergei Katsev has pushed a major milestone in the evolution of Earth’s environment back by about 250 million years. While oxygen is believed to have first accumulated in Earth’s atmosphere around 2.45 billion years ago, new research shows that oceans contained plentiful oxygen long before that time, providing energy-rich habitat for early life. The results of the two UMD scientists and their co-author Sean Crowe from the University of British Columbia have been published in the peer-reviewed journal Science Advances.

“When tiny bacteria in the ocean began producing oxygen, it was a major turning point and changed the chemistry of the Earth,” explained Katsev. “Our work pinpoints the time when the ocean began accumulating oxygen at levels that would substantially change the ocean’s chemistry and it’s about 250 million years earlier than what we knew for the atmosphere. That is about the length of time from the first appearance of dinosaurs till today.”

The results are important, according to the authors, because they deepen our understanding of conditions on Earth when all life consisted of single-cell microbes and their metabolisms that we know today were only just emerging.

“This helps us theorize not only about early life on Earth but also about the signatures of life that we might find on other planets,” said Fakhraee.

The study conclusions are the result of creating a detailed computer model of chemical reactions that took place in the ocean’s sediments. Researchers focused on the cycle of sulfur and simulated the patterns in which three different isotopes of sulfur could combine in ancient sedimentary rocks. By comparing the model results to a large amount of data from ancient rocks and seawater, they were able to determine how sulfur and oxygen levels were linked and constrained the concentrations of oxygen and sulfate in ancient seawater.

“We’re trying to reconstruct the functioning of early life and early environments,” said Katsev. “No one was really looking at how the isotopic signals that were being generated in the atmosphere and the ocean were being transformed in the sediment. But all that we can observe now is what has been preserved as rocks, and the isotopic patterns could have been modified in the process.”

Much of this research builds on the past work of the team members, and the modeling results help put together some of the observations that seemed contradictory. “We’ve resolved some puzzles in the historical timeline and contradictions that existed in the sulfur isotope records,” said Fakhraee.

Reference:
Mojtaba Fakhraee, Sean A. Crowe, Sergei Katsev. Sedimentary sulfur isotopes and Neoarchean ocean oxygenation. Science Advances, 2018; 4 (1): e1701835 DOI: 10.1126/sciadv.1701835

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

Rare 450 million year-old ‘cone-shaped’ fossil offers enigmatic glimpse into ancient past

Hummelstown Fossils. A) Typical specimen reconstruction showing body mass (white) poking out of the 'spindle'-shaped cone (patterned). Note the presence of 'spikes' on the sides of the exposed body. B) Typical fossil specimen with body mass (with at least one spike) and 'spindle'-shaped cone. C) Surface of rock slab showing numerous Hummelstown fossils.
Hummelstown Fossils. A) Typical specimen reconstruction showing body mass (white) poking out of the ‘spindle’-shaped cone (patterned). Note the presence of ‘spikes’ on the sides of the exposed body. B) Typical fossil specimen with body mass (with at least one spike) and ‘spindle’-shaped cone. C) Surface of rock slab showing numerous Hummelstown fossils. Credit: University of Leicester

Researchers from the University of Leicester, working with an international team of geologists, have discovered an enigmatic fossil of a 450 million year-old creature resembling a tiny ice-cream cone.

Fossils of the creature, in which the ‘body’ resembles a scoop of ice cream atop the cone, was located in the Appalachian Mountains, near Hummelstown in Pennsylvania from the Ordovician period.

Intriguingly, the rocks in which the fossil was found have been ‘cooked’ during mountain building, which usually hinders fossil preservation.

Discovered by consulting geologist Bob Ganis, who obtained his PhD from the University of Leicester, and Mike Meyer of the Carnegie Institute of Science, it has now been described in a paper published in the journal Palaios by them and co-authors Professor Jan Zalasiewicz of the University of Leicester, Jacalyn Wittmer of the State University of New York, Geneseo and Kenneth de Baets of Geozentrum Nordbayern in Erlangen Germany.

The paper discusses the possibilities of this newly found soft-bodied creature, which lived among the plankton before being carried to the sea floor and buried within mud slurries.

Professor Jan Zalasiewicz from the University of Leicester’s School of Geography, Geology and the Environment, said: “The ancient world of the Ordovician, some 450 million years ago, was one of a huge expansion of life in the seas of our planet.

“Fossils are abound in Ordovician strata, but almost all of them are of creatures with hard shells or support structures, and so our understanding of booming Ordovician life is almost completely based on skeleton-bearing animals. There are few of those rare, precious localities where softer-bodied animals might be found, to give a wider insight into the life of those times.

“Was this creature an important but usually unpreserved part of ocean life, or just a bit player among the Ordovician animal communities? It is a new puzzle for palaeontologists.”

Mike Meyer, of the Carnegie Institute of Science, said: “That this fossil still has the soft bits preserved, even though the rocks that hold it have been squeezed and twisted, is remarkable. This enigmatic organism has major implications for how we look for well-preserved fossils.”

Bob Ganis added: “It’s a small fossil with a big story.”

Reference:
Mike B. Meyer, G. Robert Ganis, Jacalyn M. Wittmer, Jan A. Zalasiewicz, Kenneth De Baets. A LATE ORDOVICIAN PLANKTIC ASSEMBLAGE WITH EXCEPTIONALLY PRESERVED SOFT-BODIED PROBLEMATICA FROM THE MARTINSBURG FORMATION, PENNSYLVANIA. PALAIOS, 2018; 33 (1): 36 DOI: 10.2110/palo.2017.036

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

Oxidized iron deep within Earth’s interior

Diamonds with garnet inclusions can form at depths down to 550 kilometres below the surface. Credit: Jeff W. Harris, University of Glasgow.

Scientists digging deep into the Earth’s mantle recently made an unexpected discovery.

Five hundred and fifty kilometres below the Earth’s surface, they found highly oxidized iron, similar to the rust we see on our planet’s surface, within garnets found within diamonds.

The result surprised geoscientists around the globe because there is little opportunity for iron to become so highly oxidized deep below the Earth’s surface.

Surprising discovery

“On Earth’s surface, where oxygen is plentiful, iron will oxidize to rust,” explained Thomas Stachel, professor in the Department of Earth and Atmospheric Sciences at the University of Alberta, who co-authored the study. “In the Earth’s deep mantle, we should find iron in its less oxidized form, known as ferrous iron, or in its metal form. But what we found was the exact opposite — the deeper we go, the more oxidized iron we found.”

This discovery suggests that something oxidized the rocks in which the superdeep diamonds were founds. The scientists suspect that it was molten carbonate, carried to these great depths in sinking slabs of ancient sea floor.

“It’s exciting to find evidence of such profound oxidation taking place deep inside the Earth,” said Stachel, Canada Research Chair in diamonds.

Carbon cycle

The study also has implications for understanding the global carbon cycle that involves the transport of surface carbon back into the Earth’s mantle.

“We know lots about the carbon cycle on Earth’s surface, but what about in the mantle?” explained Stachel. “Our study suggests that surface carbon goes down as carbonates to at least 550 kilometres below the surface. There, these carbonates may melt and react with the surrounding rocks, eventually crystallizing into diamonds. Diamonds can then be taken down even deeper in the mantle.”

The study shows that the carbon cycle extends deep into mantle, possibly all the way down to the core-mantle boundary, with billion year storage times.

Reference:
Ekaterina S. Kiseeva, Denis M. Vasiukov, Bernard J. Wood, Catherine McCammon, Thomas Stachel, Maxim Bykov, Elena Bykova, Aleksandr Chumakov, Valerio Cerantola, Jeff W. Harris, Leonid Dubrovinsky. Oxidized iron in garnets from the mantle transition zone. Nature Geoscience, 2018; DOI: 10.1038/s41561-017-0055-7

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

Earth’s core and mantle separated in a disorderly fashion

Earth experienced multiple large impacts; the high-pressure and -temperature conditions caused pockets of core and mantle partitioning that persist as chemically distinct today.
Earth experienced multiple large impacts; the high-pressure and -temperature conditions caused pockets of core and mantle partitioning that persist as chemically distinct today. Credit: Neil Bennett

Plumes of hot rock surging upward from the Earth’s mantle at volcanic hotspots contain evidence that the Earth’s formative years may have been even more chaotic than previously thought, according to new work from a team of Carnegie and Smithsonian scientists published in Nature.

It is well understood that Earth formed from the accretion of matter surrounding the young Sun. Eventually the planet grew to such a size that denser iron metal sank inward, to form the beginnings of the Earth’s core, leaving the silicate-rich mantle floating above.

But new work from a team led by Carnegie’s Yingwei Fei and Carnegie and the Smithsonian’s Colin Jackson argues that this mantle and core separation was not such an orderly process.

“Our findings suggest that as the core was extracted from the mantle, the mantle never fully mixed,” Jackson explained. “This is surprising because core formation happened in the immediate wake of large impacts from other early Solar System objects that Earth experienced during its growth, similar to the giant impact event that later formed the Moon. Before now, it was widely thought that these very energetic impacts would have completely stirred the mantle, mixing all of its components into a uniform state.”

The smoking gun that led the team to their hypothesis comes from unique and ancient tungsten and xenon isotopic signatures found at volcanic hotspots, such as Hawaii. Although it was believed that these plumes originated from the mantle’s deepest regions, the origin of these unique isotopic signatures has been debated. The team believes that the answer lies in the chemical behavior of iodine, the parent element of xenon, at very high pressure.

Isotopes are versions of elements with the same number of protons, but different numbers of neutrons. Radioactive isotope of elements, such as iodine-129, are unstable. To gain stability, iodine-129 decays into xenon-129. Therefore, the xenon isotopic signatures in plume mantle samples are directly related to iodine’s behavior during the period of core-mantle separation.

Using diamond anvil cells to recreate the extreme conditions under which Earth’s core separated from its mantle, Jackson, Fei, and their colleagues — Carnegie’s Neil Bennett and Zhixue Du and Smithsonian’s Elizabeth Cottrell — determined how iodine was partitioning between metallic core and silicate mantle. They also demonstrated that if the nascent core separated from the deepest regions of the mantle while it was still growing, then these pockets of the mantle would possess the chemistry needed to explain the unique tungsten and xenon isotopic signatures, provided these pockets remained unmixed with the rest of the mantle all the way up through the present day.

According to Bennett: “The key behavior we identified was that iodine starts to dissolve into the core under very high pressures and temperatures. At these extreme conditions, iodine and hafnium, which decay radioactively to xenon and tungsten, display opposing preferences for core-forming metal. This behavior would lead to the same unique isotopic signatures now associated with hotspots.”

Calculations from the team also predict that the tungsten and xenon isotopic signatures should be associated with dense pockets of the mantle.

“Like chocolate chips in cookie batter, these dense pockets of the mantle would be very difficult stir back in, and this may be a crucial aspect to the retention of their ancient tungsten and xenon isotopic signatures to the modern day,” Jackson explained.

“Even more exciting is that there is increasing geophysical evidence that there actually are dense regions of mantle, resting just above the core — called ultralow velocity zones and large low shear velocity provinces. This work ties together these observations,” Fei added. “The methodology developed here also opens new opportunities for directly studying the deep Earth processes.”

This work was supported by the National Science Foundation, the Carnegie Institution for Science, and the Smithsonian Institution.

Reference:
Colin R. M. Jackson, Neil R. Bennett, Zhixue Du, Elizabeth Cottrell & Yingwei Fei. Early episodes of high-pressure core formation preserved in plume mantle. Nature, 2018 DOI: 10.1038/nature25446

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

Shedding light on Australia’s polar dinosaurs

The fossil bone tissue reveals new information about how the Australian “hypsilophodontid” dinosaurs lived
The fossil bone tissue reveals new information about how the Australian “hypsilophodontid” dinosaurs lived. Credit: Peter Trusler

Dinosaurs that lived in what is now known as Victoria more than 120 million years ago would have dealt with prolonged periods of darkness and below freezing temperatures, a new study reveals.

The study, published in the Scientific Reports journal, examines the bone tissue microstructure of plant-eating “hypsilophodontid” dinosaurs known to have lived in the Antarctic Circle—now Victoria, Australia.

“These little dinosaurs would have dealt with prolonged periods of darkness and mean annual temperatures near freezing, and certainly below freezing in the winter,” says one of the study authors, Dr. Patricia Vickers-Rich, a professor of paleobiology at Swinburne.

In studying fossils from seventeen individuals, the International research team from Swinburne University of Technology, Oklahoma State University, Museums Victoria, and Monash University produced the first life history reconstructions for these small Australian polar dinosaurs.

Examining bone microstructure

An examination of the bone microstructure, or histology, of the hypsilophodontid fossils revealed many characteristics of their growth.

Rings in the bone, similar in appearance to tree rings, helped determine individual age. Bone fibre orientation, blood vessel density, and the amount of bone between growth rings, was used to determine annual growth rates.

Bone histology revealed that, in general, growth was most rapid during the first three years of life, and the dinosaurs were fully grown – the size of a medium wallaby or average turkey—in five to seven years.

Uncovering Australia’s past

The hypsilophodontid samples were recovered from two Australian localities along the south Victorian coast stretching from west of Cape Otway to Inverloch, geologically separated by about 12 million years.

However, the trend of rapid growth for three years followed by adult body size between five and seven years, was conserved across the two samples.

“Given the geologic time involved, we may be looking at several polar dinosaur species in this sample, but their growth trajectories are so similar that we cannot differentiate them from one another based on their growth patterns and rates alone,” says Holly Woodward (Oklahoma State University).

“Instead, our life history assessment demonstrates to us that this generalised growth trajectory was a successful lifestyle for surviving in a region experiencing unique conditions.”

Histologic examinations

The tibia (shin-bone) of one hypsilophodontid individual in the sample had clearly suffered from a pathologic condition known as osteomyelitis or bone infection.

Microscopic examination revealed the cause of this pathology was most likely a broken bone, which then became infected. Counting the growth rings preserved in this tibia prior to the formation of the pathologic bone, the team was able to place the timing of the injury as having occurred when this individual was approximately four years old.

The team was also able to tease out how long this little dinosaur lived and how it dealt with the injury: histologic examination of the unaffected femur (thigh bone) of this individual shows that it survived with the injury and pathology for three more years.

“Further investigations of this unique sample will continue to shed light on how these little dinosaurs thrived in high latitudes and under the most stressful of environments during a time when dinosaurs flourished on planet Earth,” Dr. Vickers-Rich says.

Reference:
Holly N. Woodward et al. The bone microstructure of polar “hypsilophodontid” dinosaurs from Victoria, Australia, Scientific Reports (2018). DOI: 10.1038/s41598-018-19362-6

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

Tidal cycles could help predict volcanic eruptions

Ruapehu Volcano
Ruapehu Volcano. Credit: Greg Steenbeeke

Just before a surprise eruption of New Zealand’s Ruapehu volcano in 2007, seismic tremor near its crater became tightly correlated with twice-monthly changes in the strength of tidal forces, a new study has found. The research, published in the journal Scientific Reports, suggests that signals associated with tidal cycles could potentially provide advanced warning of certain types of volcanic eruptions.

“Looking at data for this volcano spanning about 12 years, we found that this correlation between the amplitude of seismic tremor and tidal cycles developed only in the three months before this eruption,” said Társilo Girona, the study’s lead author. “What that suggests is that the tides could provide a probe for telling us whether or not a volcano has entered a critical state.”

Girona, a NASA postdoctoral fellow at the Jet Propulsion Laboratory, led the research during a postdoctoral appointment at Brown University, working with Brown professor Christian Huber and Corentin Caudron, a postdoctoral researcher at the Ghent University in Belgium.

Earth’s tides rise and fall daily due to the gravitational tug of the Moon as the Earth rotates. During full and new Moons, the lunar gravitational pull lines up with that of the sun, which makes the daily tidal bulges a little larger during those Moon phases. During the first- and third-quarter Moons, the daily tidal bulge is a little smaller. This twice-monthly change in tidal amplitude is sometimes referred to as the fortnightly tide. While we normally think of tides in terms of rising and falling waters, these gravitational stresses also affect the planet’s solid crust. The question of whether gravitational stresses may influence volcanic activity is longstanding in the Earth sciences.

“A lot of research has been focused on whether or not tidal forces can trigger eruptions, and there’s no definitive evidence whatsoever that they do,” Huber said. “We wanted to take a different angle with this study and look at whether there’s some detectable signal associated with tidal forces that can tell us something about a volcano’s criticality.”

The researchers chose to study Ruapehu volcano in part because its activity has been closely monitored for years by GNS Science, a research institute in New Zealand. The mountain is a popular tourist attraction and home to two ski resorts, so officials want to be aware of any warning signs that it might erupt. That monitoring provided a long and continuous data set for the researchers to study.

In particular, the team was interested in data from seismic sensors located near the volcano’s crater. Those sensors pick up volcanic tremor, a low-level seismic rumble that provides a persistent signal of activity within a volcanic system. Using a sophisticated statistical technique, the researchers combed through 12 years of seismic data, looking for any period when the seismicity was correlated with lunar cycles. They found that for most of those 12 years, there was no correlation between tremor and lunar cycles, except the few months before a steam-driven eruption on Sept. 25, 2007, when a strong correlation emerged.

During those three months, the amplitude of tremor rose and fell ever so slightly in lock step with the fortnightly tidal cycle. While the fluctuations in seismic amplitude were subtle, the strength of the correlation to the tidal cycle was not. The correlation was as strong as 5 sigma, the researchers say, meaning that the probability that pattern arose by chance is about one in 3.5 million.

To understand how tidal forces were affecting Ruapehu during those three months, the researchers used a model of seismic tremor that they had developed previously. Volcanoes like Ruapehu have a vertical conduit through which lava rises, and a solid rock plug at the top. Gases released from the lava form a pocket between the rocky plug and the lava pool. That gas pocket can resonate against the plug, which creates seismic tremor.

The model suggests that when the pressure of the gas pocket reaches a critical level — a level at which a steam eruption is possible — the differing stresses associated with changing tidal forces are enough to change the amplitude of tremor.

“That’s what we think was happening in 2007,” Huber said. “When the pressure in the system became critical, it became sensitive to the tides. We were able to show that the signal is detectable.”

None of the other indicators geologists typically use to anticipate eruptions raised any warning flags in 2007. So a tidal signal could be a way of predicting steam-driven eruptions, which are otherwise hard to predict.

“We’d like to collect more data from other eruptions and other volcanos to see if this tidal signal shows up elsewhere,” Huber said. “Then we can start to think about using it as a potential means of predicting future eruptions of this kind.”

The research was funded by the National Science Foundation (1454821).

Reference:
Társilo Girona, Christian Huber, Corentin Caudron. Sensitivity to lunar cycles prior to the 2007 eruption of Ruapehu volcano. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-19307-z

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

Tiny crystals could help predict volcanic eruptions

Stromboli Volcano
Stromboli Volcano. Credit: John Caulfield

They can be as small as a grain of salt, but tiny crystals that form deep in volcanoes may be the key for advance warnings before volcanic eruptions.

University of Queensland vulcanologist Dr Teresa Ubide said the research provided new information that could lead to more effective evacuations and warning communications.

“This could signal good news for the almost one in 10 people around the world who live within 100km of an active volcano,” she said.

“We haven’t yet reached the ‘holy grail’ of being able to predict volcanic eruptions, but our research is a significant step forward in understanding the processes that lead to eruption.”

Dr Ubide, from UQ’s School of Earth and Environmental Sciences, used a new laser technique to examine the composition of tiny crystals forming deep in volcanoes.

The crystals are created when molten rock — magma — from up to 30 km beneath a volcano starts to move upwards towards the Earth’s surface.

The crystals are carried in the erupting magma, continuing to crystallise and change in composition on the way to the surface.

“They effectively ‘record’ the processes that happen deep in the volcano right before the eruption starts,” says Dr Ubide.

“We’ve found by studying these crystals in a specific volcano that, when new magma arrives at depth, up to 90 per cent of the time it can trigger an eruption, and within only two weeks.”

From this, vulcanologists hope to work out how to better monitor volcanoes — for instance, at what depths underground to look for signs of magma movement before an eruption.

Dr Ubide said it was currently very difficult to predict volcanic eruptions — as evidenced by the eruption at Mount Agung in Bali, which started last November after 2 months of precursory earthquakes.

“The Bali eruption led to the evacuation of more than 70,000 people and caused massive disruptions in air traffic and tourism, affecting more than 100,000 travellers,” she said.

“Volcanic ash and gas clouds rose to heights of up to 4 km above the summit and produced ash-fall in downwind areas.

“Lahars (mudflows) impacted houses, roads and agricultural areas.

“Every volcano is different and requires individual monitoring.”

Dr Ubide’s team tracked eruptions, their triggers and time scales at Mount Etna, on Sicily in Italy, Europe’s most active volcano.

The results could provide important information for future volcanic monitoring efforts at the site, she said.

“We plan to apply the same approach to other volcanoes around the world, especially for countries neighbouring Australia like Indonesia and New Zealand,” she says.

Reference:
Teresa Ubide, Balz S. Kamber. Volcanic crystals as time capsules of eruption history. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-017-02274-w

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

New Eocene fossil data suggest climate models may underestimate future polar warming

Foraminifera, small single-celled marine organisms
Foraminifera, small single-celled marine organisms, form their shells in concert with the ocean’s temperature and chemistry. Like tiny time capsules, they can reveal the climate conditions of millions of years ago. Credit: Laura Cotton

A new international analysis of marine fossils shows that warming of the polar oceans during the Eocene, a greenhouse period that provides a glimpse of Earth’s potential future climate, was greater than previously thought.

By studying the chemical composition of fossilized foraminifera, tiny single-celled animals that lived in shallow tropical waters, a team of researchers generated precise estimates of tropical sea surface temperatures and seawater chemistry during the Eocene Epoch, 56-34 million years ago. Using these data, researchers fine-tuned estimates from previous foram studies that captured polar conditions to show tropical oceans warmed substantially in the Eocene, but not as much as polar oceans.

Importantly, when modern climate models — the same as those used in the United Nations’ recent Intergovernmental Panel on Climate Change reports — were run under Eocene conditions, many could not replicate these findings. Instead, the models consistently underestimated polar ocean warming in the Eocene.

This discrepancy may result from a gap in our understanding of the climate system or from what we know about the Eocene, said David Evans, the study’s lead author and Leverhulme Research Fellow at the University of St Andrews’ School of Earth and Environmental Sciences. If it does indeed relate to the climate system, it raises the possibility that predictions of future polar warming are also too low.

“Yes, the tropics are warming but nowhere near to the same degree as the polar regions,” Evans said. “That’s something we really need to be able to understand and replicate in climate models. The fact that many models are unable to do that at the moment is worrying.”

The researchers published their findings this week in the Proceedings of the National Academy of Sciences.

Scientists frequently look to the Eocene to understand how the Earth responds to higher levels of carbon dioxide. During the Eocene, the concentration of carbon dioxide in the atmosphere was more than 560 parts per million, at least twice preindustrial levels, and the epoch kicked off with a global average temperature more than 8 degrees Celsius — about 14 degrees Fahrenheit — warmer than today, gradually cooling over the next 22 million years. These characteristics make the Eocene a good period on which to test our understanding of the climate system, said Laura Cotton, study co-author and curator of micropaleontology at the Florida Museum of Natural History.

One of the challenges has been accurately determining the difference between sea surface temperatures at the poles and the equator during the Eocene, with models predicting greater differences than data suggested.

The research team used large bottom-dwelling forams as “paleothermometers” to gain a more precise temperature reading. Forams have an exceptionally long fossil record, spanning more than 540 million years, and they are often well-preserved in ocean sediments. Most are small enough to fit into the eye of a needle — Cotton describes them as “an amoeba with a shell” — but they were so abundant during the Eocene that there are entire rocks composed of them.

“If you look at the pyramids, they’re full of these tiny little lentil-like things — those are forams,” Cotton said. “The ancient Greeks thought the pyramids were made from the fossilized lentils of slaves, but it’s just the limestone from one of these deposits that is absolutely filled with them.”

Forams form their shells in concert with ocean temperatures and chemistry, acting as miniscule time capsules, each containing a precise record of the temperature and ocean chemistry during its lifetime. Their shells are primarily made of calcium, carbon and oxygen. Heavy isotopes of carbon and oxygen bond together as a foram makes its shell — the cooler the temperature, the more they bond to each other.

By analyzing these clumped isotopes from fossil specimens found in India, Indonesia and Tanzania, the researchers could get an accurate reading of sea surface temperature across the tropics in the Eocene. They also lasered a small hole in each specimen to measure the amount of magnesium and calcium that vaporized, revealing the seawater chemistry.

They found that tropical sea surface temperature in the Eocene was about 6 degrees Celsius — about 10 degrees Fahrenheit — warmer than today.

“This was the first time we had samples that were good enough and this method was well-known enough that it could all come together,” Cotton said.

The team then used their dataset from the tropics to back-calculate the temperature and chemistry of polar oceans, relying on previous studies of forams that captured the conditions of those regions.

With this correction factor in place, they investigated the degree to which polar oceans warmed more than the tropics, a feature of the climate system known as polar amplification. Their data showed that the difference between polar and equatorial sea surface temperatures in the Eocene was an estimated 20 degrees Celsius, about 36 degrees Fahrenheit. Today the difference is 28 degrees Celsius, indicating that polar regions are more sensitive to increases in atmospheric carbon dioxide than the tropics.

Troublingly, said Evans, when the team compared their data with various modern climate models under Eocene conditions, most models underestimated polar amplification by about 50 percent.

The two models that came closest to reproducing the team’s data had one key aspect in common — they modified the way they accounted for cloud formation and the longevity of clouds in the atmosphere, particularly in the polar regions.

“To us, that looks like a promising research direction,” he said. “If — and it’s a big if — that turns out to be the right avenue to go down, that could play into the models we use for our future climate predictions.”

Reference:
David Evans, Navjit Sagoo, Willem Renema, Laura J. Cotton, Wolfgang Müller, Jonathan A. Todd, Pratul Kumar Saraswati, Peter Stassen, Martin Ziegler, Paul N. Pearson, Paul J. Valdes, Hagit P. Affek. Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry. Proceedings of the National Academy of Sciences, 2018; 201714744 DOI: 10.1073/pnas.1714744115

Note: The above post is reprinted from materials provided by Florida Museum of Natural History.

New 508-million-year-old bristle worm species from British Columbia’s Burgess Shale wiggles into evolutionary history

Kootenayscolex barbarensis
Life reconstruction of Kootenayscolex barbarensis. Credit: Danielle Dufault, 2018 © Royal Ontario Museum

Researchers at the Royal Ontario Museum and the University of Toronto have described an exceptionally well-preserved new fossil species of bristle worm called Kootenayscolex barbarensis. Discovered from the 508-million-year-old Marble Canyon fossil site in the Burgess Shale in Kootenay National Park, British Columbia, the new species helps rewrite our understanding of the origin of the head in annelids, a highly diverse group of animals which includes today’s leeches and earthworms. This research was published today in the journal Current Biology in the article A New Burgess Shale Polychaete and the Origin of the Annelid Head Revisited.

“Annelids are a hugely diverse group of animals in both their anatomies and lifestyles,” said Karma Nanglu, a University of Toronto PhD candidate, and a researcher at the Royal Ontario Museum, as well as the study’s lead author. “While this diversity makes them ecologically important and an evolutionarily interesting group to study, it also makes it difficult to piece together what the ancestral annelid may have looked like.”

Annelids are found in nearly all marine environments from hydrothermal vents to coral reefs to the open ocean, and also include more evolutionary derived species living on land today. Although quite abundant in modern environments, their early evolutionary history, in particular the origin of their heads, is confounded by a relatively poor fossil record, with few species described from well-preserved body fossils near the evolutionary origins of the group.

Co-author Dr. Jean-Bernard Caron, Senior Curator of Invertebrate Palaeontology at the Royal Ontario Museum, Associate Professor in the departments of Ecology & Evolutionary Biology and Earth Sciences at U of T, and Nanglu’s PhD supervisor, said: “While isolated pieces of annelid jaws and some annelid tubes are well known in the fossil record, preservation of their soft tissues is exceedingly rare. You need to look to truly exceptional fossil deposits like those found in the 508-million-year-old Burgess Shale locality in British Columbia to find well preserved body fossils. Even then, they’re quite uncommon and many of the currently described species there are still poorly understood.”

One key feature of the new Burgess Shale worm Kootenayscolex barbarensis is the presence of hair-sized bristles called chaetae on the head which led Nanglu and Caron to propose a new hypothesis regarding the early evolution of the head in annelids. “Like other bristle worms, Kootenayscolex possesses paired bundles of hair-sized bristles spread along the body; this is in fact one of the diagnostic features of this group of animals,” Nanglu added. “However, unlike any living forms, these bristles were also partially covering the head, more specifically surrounding the mouth. This new fossil species seems to suggest that the annelid head evolved from posterior body segments which had pair bundles of bristles, a hypothesis supported by the developmental biology of many modern annelid species.”

The Cambrian Period (541-485 million years ago) represents the first time that most animal groups appear in the fossil record, however, many species often possessed morphologies that were very unlike their modern relatives. “Coupling new fossil discoveries, such as Kootenayscolex, with a deeper understanding of developmental processes presents a powerful tool for investigating these unique morphologies and, ultimately, the origin of modern animal diversity,” added Dr. Caron.

The description of Kootenayscolex is one of many new discoveries from the Burgess Shale site called Marble Canyon (Kootenay National Park) which are changing the way we think about the evolution of a wide array of animal groups. Dr. Caron led the ROM research team that uncovered this new locality in 2012, 40 km southeast of the original Burgess Shale site (Yoho National Park) in the Canadian Rockies. This new bristle worm is not only the most abundant species of annelid throughout the entire fossil record with more than 500 specimens recovered, but also the best preserved so far. “Some specimens preserved remnants of internal tissues, including possible nervous tissues, which is the first time we see evidence of such delicate features in a fossil annelid. This exceptional preservation opens a new chapter in the study of these ancient worms” added Caron.

“508 million years ago, the Marble Canyon would have been teeming with annelids,” said Nanglu. “The fine anatomical details preserved in Kootenayscolex allow us to infer not only its evolutionary position, but also its lifestyle. Sediment preserved inside their guts suggest that, much as their relatives do in modern ecosystems, these worms served an important role in the food chain by recycling organic material from the sediment back to other animals that preyed on them.”

The new annelid’s species name, barbarensis, was chosen to honour Barbara Polk Milstein, who is a Royal Ontario Museum volunteer and longtime supporter of Burgess Shale research. Kootenayscolex barbarensis is brought to life by ROM visual artist and scientific illustrator Danielle Dufault.

Reference:
Karma Nanglu et al. A New Burgess Shale Polychaete and the Origin of the Annelid Head Revisited. Current Biology, 2017 DOI: 10.1016/j.cub.2017.12.019

Note: The above post is reprinted from materials provided by Royal Ontario Museum.

Heat loss from the Earth triggers ice sheet slide towards the sea

Several glaciers flow into the area of Young Sound where researchers have shown that heat from the Earth's interior warms up the bottom water of the fjord.
Several glaciers flow into the area of Young Sound where researchers have shown that heat from the Earth’s interior warms up the bottom water of the fjord. Credit: Mikael Sejr

Greenland’s ice sheet is becoming smaller and smaller. The melting takes place with increased strength and at a speed that no models have previously predicted.

Today, in the journal Scientific Reports, researchers from the Arctic Research Centre, Aarhus University, and the Greenland Institute of Natural Resources present results that, for the first time, show that the deep bottom water of the north-eastern Greenland fjords is being warmed up by heat gradually lost from the Earth’s interior. And the researchers point out that this heat loss triggers the sliding of glaciers from the ice sheet towards the sea.

Icelandic conditions

“North-East Greenland has several hot springs where the water becomes up to 60 degrees warm and, like Iceland, the area has abundant underground geothermal activity,” explains Professor Soren Rysgaard, who headed the investigations.

For more than ten years, the researchers have measured the temperature and salinity in the fjord Young Sound, located at Daneborg, north of Scoresbysund, which has many hot springs, and south of the glacier Nioghalvfjerdsfjorden, which melts rapidly and is connected to the North-East Greenland Ice Stream (NEGIS).

By focusing on an isolated basin in the fjord with a depth range between 200 and 340 m, the researchers have measured how the deep water is heated over a ten-year period. Based on the extensive data, researchers have estimated that the loss of heat from the Earth’s interior to the fjord is about 100 MW m-2. This corresponds to a 2 megawatt wind turbine sending electricity to a large heater at the bottom of the fjord all year round.

Heat from the Earth’s interior — an important influence

It is not easy to measure the geothermal heat flux — heat emanating from the Earth’s interior — below a glacier, but within the area there are several large glaciers connected directly to the ice sheet. If the Earth releases heat to a fjord, heat also seeps up to the bottom part of the glaciers. This means that the glaciers melt from below and thus slide more easily over the terrain on which they sit when moving to the sea.

“It is a combination of higher temperatures in the air and the sea, precipitation from above, local dynamics of the ice sheet and heat loss from the Earth’s interior that determines the mass loss from the Greenland ice sheet,” explains Soren Rysgaard.

“There is no doubt that the heat from the Earth’s interior affects the movement of the ice, and we expect that a similar heat seepage takes place below a major part of the ice cap in the north-eastern corner of Greenland,” says Soren Rysgaard.

The researchers expect that the new discoveries will improve the models of ice sheet dynamics, allowing better predictions of the stability of the Greenland ice sheet, its melting and the resulting global water rise.

Reference:
Søren Rysgaard, Jørgen Bendtsen, John Mortensen, Mikael K. Sejr. High geothermal heat flux in close proximity to the Northeast Greenland Ice Stream. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-19244-x

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

Arsenic and permafrost microbes help hunt for life on Mars

Bacteria survive in the harsh conditions of the Andean lakes of Argentina among high concentrations of arsenic.
Bacteria survive in the harsh conditions of the Andean lakes of Argentina among high concentrations of arsenic. Credit: ASLIFE project

Studying environments that are similar to Mars, and their microbial ecosystems, could help prepare biologists to identify traces of life in outer space.

In some of the most remote areas of our planet, scientists are examining how life can persist in the form of tiny microbes that inhabit a niche that would be fatal to the vast majority of organisms on Earth.

Living off toxic substances like arsenic, or in oxygen-free zones, these hardy microbes metabolise food and nutrients in completely different ways from most plants, animals and humans. Some move and metabolise so slowly, for example, that until recently scientists did not even consider them to be alive.

The harsh environments where they live are similar to conditions found on Mars and other planets, and by furthering our understanding of how these microbial communities work, space geobiologists will be better equipped to identify signs of extra-terrestrial life.

Dr. Amedea Perfumo of the GFZ German Research Centre for Geosciences leads the EU-funded BIOFROST project, which is investigating how organisms survive in the deep biosphere of Earth’s permafrost, where temperatures are sub-zero and there is a lack of oxygen.

‘These anoxic and frozen conditions are extremely relevant for space exploration. It’s an analogue for Mars,’ she said. ‘It’s about finding what the limits for life on Earth are under the most similar conditions to space and seeing if we can have a better interpretation of what might come out from a space mission.’

BIOFROST focused on building up a so-called on-filter analytic pipeline, where information about live bacteria, such as how many there are of which type, how active they are and how they interact with each other are extracted from the permafrost sediment and collected onto a special gold-platinum-coated filter.

‘I am supported by some of the most forefront techniques, which include NanoSIMS and nano-spectroscopy, and I hope, in particular, to provide scientific evidence to the basic functioning of a cell under such extreme conditions and how this impacts on the permafrost’s ecosystem functioning,’ said Dr. Perfumo.

Adaptations

The permafrost microorganisms being studied by Dr. Perfumo have developed unique adaptations to their freezing, oxygen-free zones. Their metabolism is so slow, for example, that it is only recently that technology has become sophisticated enough to detect that the organisms are even alive.

Ecological adaptation can come at a cost, however. Because they’ve evolved to fit so perfectly into their niche, any kind of temperature change can spell trouble for the organisms. In previous experiments, Dr. Perfumo found that when the heat was turned up by only 5 degrees Celsius, the bacteria died.

This shows a very low tolerance for change in environmental conditions, unlike many other kinds of bacteria. The various species of bacteria that we tend to find at room temperatures, for example, need to be able to survive fluctuating weather conditions, whereas deep permafrost bacteria are generally guaranteed to live at constant, though very cold, temperatures.

Arsenic

High up in the Andean lakes of Argentina, researchers are exploring another so-called extremophile organism – bacteria that survive in high concentrations of arsenic. The World Health Organization recommends that drinking water should have no more than 10 micrograms of arsenic per litre, but these lakes contain four or five orders of magnitude more.

The conditions in fact mimic life on prehistoric Earth. ‘When you are there, it’s like you are on Earth 3 500 million years ago,’ says Dr. Maria Sancho-Tomas of the Institut de Physique du Globe de Paris, France, who leads the ASLIFE project to investigate the bacteria. ‘It’s amazing. If you look at the landscape, it’s like Mars.’

On prehistoric Earth, organisms had to develop strategies to either fight or adapt to the arsenic. Microbes like those being studied by Dr. Sancho-Tomas used arsenic in their metabolic systems, converting the mineral to energy, in a process not unlike the way that humans break down food.

The ASLIFE researchers are analysing earth cores by drilling a hole in the ground and extracting a cylinder of material to take back to the laboratory for further analysis. According to Dr. Sancho-Tomas, the parts of the sediment from the lakes that contain arsenic can clearly be seen – they are purple, as the arsenic interacts with sulphur.

The team is also taking scrapings from stromatolites, ancient organic structures that can be billions of years old and are created by microorganisms. The samples are then taken to synchrotron facilities at the SOLEIL plant near Paris, France, to get a closer look at the inner workings of these organisms.

The idea is to establish whether certain arsenic variants – or isotopes – could be used as biosignatures – chemical indicators that life is, or was, present. If so, space scientists could look for the same signatures on other planets and infer that life existed there, even if the microorganisms themselves remain elusive.

In the process, the researchers are also coming up with new ways of transporting and examining these microbes, samples of which can deteriorate due to factors such as temperature and pressure changes. Astrobiologists will be able to use these methods to ensure that any extraterrestrial samples found will be transported back to Earth unharmed.

Closer to home

However, learning more about extremophiles also has practical applications closer to home. Dr. Perfumo is working on adapting enzymes and molecules with slippery surfaces, known as biosurfactants, from these cold-loving bacteria to lower the temperatures needed for many commercial and industrial activities, which will be beneficial for the environment.

Dr. Sancho-Tomas and her colleagues are making a high-resolution map of the distribution of the arsenic-loving bacteria in the Andes. This information could then be used to determine arsenic-contaminated areas around the world, for example in Vietnam and India.

What’s more, the bacteria they are examining could eventually be used as bioremediators – that is, natural microorganisms that clear environmental pollutants from a site. Further genetic analysis of the arsenic-consuming bacteria will be needed before the relevant enzymes can be identified for this.

Note: The above post is reprinted from materials provided by Horizon: The EU Research & Innovation Magazine.

The seemingly unremarkable crystals that could help predict volcanic eruptions

Panoramic of Mt Etna, Sicily
Panoramic of Mt Etna, Sicily. Credit: Dr Teresa Ubide.

They may look inconspicuous and unremarkable, and most people wouldn’t notice them, but small crystals in volcanic rocks, such as lava, may hold the key to better understanding advance warnings of volcanic eruptions.

The crystals form inside the volcano when molten rock—magma—starts moving upwards from depths of up to 30 km towards the Earth’s surface. The crystals are carried in the erupting magma, and they often continue to grow as they are being transported. Importantly, they also change in composition on their way to the surface.

Two scientists—Dr Teresa Ubide from the University of Queensland, and Professor Balz Kamber from Trinity College Dublin—conducted the research in a project funded mainly by Science Foundation Ireland. They used a laser technique to examine the inside of these crystals in a novel way. And what they discovered is that the crystals contain a memory in the form of growth layers that look similar to tree rings. Reading the history from these layers may lead to more effective volcanic hazard monitoring, including for dormant volcanoes.

Dr Ubide said: “They essentially ‘record’ the processes right before the eruption starts. At Mount Etna, we found that the arrival of new magma at 10 km depth is a very efficient trigger of eruptions—and within only two weeks.”

“In this case, therefore, earth tremors at the depth of magma recharge must be taken as serious signs of potential imminent eruptions. At other volcanoes, the method will allow to establish the relationship between recharge depth, recharge frequency and eruption efficiency. This can then help scientists to better relate physical signs of recharge to eruption potential.”

The findings have just been published in leading international journal Nature Communications. The research was conducted on Mount Etna, in Sicily, which is Europe’s most active volcano. Dr Ubide’s team is now planning to expand the approach to other volcanoes around the world, and to combine the information with geophysical signs of magma movement.

It remains very difficult to predict volcanic eruptions – as evidenced by the eruption at Mount Agung in Bali, which started last November after two months of precursory earthquakes. It led to the evacuation of over 70,000 people and caused massive disruptions in air traffic and tourism, affecting over 100,000 travellers.

Professor of Geology and Mineralogy at Trinity, Balz Kamber, added: “The new approach may also prove useful for studying volcanoes that have remained dormant, such as the currently erupting volcano on Kadovar Island, Papua New Guinea.”

“For many volcanoes there is no eruption history, but geologists can collect lavas from past eruptions and study their crystals.”

Reference:
Teresa Ubide et al, Volcanic crystals as time capsules of eruption history, Nature Communications (2018). DOI: 10.1038/s41467-017-02274-w

Note: The above post is reprinted from materials provided by Trinity College Dublin.

Large volcanic island flank collapses trigger catastrophic eruptions

The summit of the Teida volcano.
The summit of the Teida volcano. Credit: Image courtesy of National Oceanography Centre (NOC)

New research, published today in Nature Scientific Reports, not only implies a link between catastrophic volcanic eruptions and landslides, but also suggests that landslides are the trigger.

At the heart of Tenerife and standing almost 4 km high, Teide is one of the largest volcanoes on Earth. Over a period of several hundred thousand years, the previous incarnations of Teide have undergone a repeated cycle of very large eruptions, collapse, and regrowth. Previous research by scientists at the National Oceanography Centre (NOC) revealed that past eruptions may have been linked to huge multi-stage submarine landslides, based on similar ages and composition of landslide and volcanic deposits.

By studying these landslide deposits further, NOC scientists noticed that material from explosive volcanic eruptions was only found in the uppermost layers of each landslide deposit. This demonstrates that the initial stages of each landslide occurred underwater and before each eruption, whilst in each case the later stages of terrestrial landsliding occurred after the eruption. These results suggest that the initial stages of the landslides may have triggered each of the eruptions.

The scientists then investigated the thin volcanic clay layers between landslide and eruption deposits, and based upon the time required for clay to settle out of the ocean, estimated the minimum time delay between the initial submarine landslide and a subsequent eruption as approximately ten hours.

NOC scientist and lead author of this research, Dr James Hunt, said “Crucially, this new research shows that after the initial submarine landslide there could be between ten hours to several weeks until the eruption is finally triggered — very different from the near-instantaneous landslide triggering of the 1980 Mt St Helens eruption. This information could help inform hazard mitigation strategies for volcanoes similar to Teide, such as Mt St Helens or Montserrat.”

Dr Hunt suggests this delay could be because the shallow magma chamber in Teide does not contain enough volatiles (water) to immediately create explosive eruptions. However, removal of volcanic material by landslides may trigger magma to rise from the lower volatile-rich magma chamber, which mixes with the shallow magma, causing explosive volcanic eruptions after a delay and leaving a large crater-like feature called a caldera that may be several kilometres across. These ‘caldera-forming’ eruptions are among the largest volcanic eruptions on Earth and involve energies equivalent to an atom bomb explosion, while the associated landslides are among the largest mass movements on Earth and can generate potentially damaging tsunamis.

This new understanding of the linkage between large volcanic islands and caldera-forming eruptions will help advise future geohazard assessments of volcanic islands, and forms part of the NOC’s on-going research into marine geohazards.

Reference:
James E. Hunt, Michael Cassidy, Peter J. Talling. Multi-stage volcanic island flank collapses with coeval explosive caldera-forming eruptions. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-19285-2

Note: The above post is reprinted from materials provided by National Oceanography Centre (NOC).

Do moon phases produce big earthquakes?

Moon
Moon

Huge earthquakes are not significantly influenced by the moon, a new study says.

The study, conducted by U.S. Geological Survey seismologist Susan Hough, looked at earthquakes of magnitude 8 or greater over the past four centuries. And a review of more than 200 earthquakes demonstrated that there is no connection between the phase of the moon and the time when huge seismic events of magnitude 8 and greater strike.

“That’s obviously a big earthquake myth: that big earthquakes happen on the full moon,” Hough said in an interview. Her study was published Tuesday in the journal Seismological Research Letters, a publication of the Seismological Society of America.

Hough said the myth can gain more attention when a large earthquake strikes on a full moon or when scientific studies show a weak influence on earthquake rates by tidal or other forces.

“In recent years, there have been a couple of nice studies that show that tidal forces do modulate earthquake rates slightly. It makes sense: The tides create stress in the solid earth, and not just the oceans. And in some cases, that small force can be ‘the straw that breaks that camel’s back’ and nudges the fault to produce an earthquake,” Hough said.

But it’s also important to understand that “this isn’t of any practical value for prediction,” Hough said.

“A recent study … for example, concluded that very large earthquakes, with magnitudes close to 9, tend to occur near the time of maximum tidal stress,” Hough said in her study, adding that researchers “point out, however, that the relationship is not clear-cut and does not hold when low-magnitude events are included in the analysis.”

Indeed, other scientists who have authored studies on the impact of tides with earthquakes have been careful to point out that many earthquakes will still happen when tidal stress is low, and note that the studies don’t mean that the public can get a warning about the exact date, time and location of the next big earthquake.

But sometimes reports of those studies, Hough said, “turn into headlines that say the moon causes earthquakes.”

Exactly when and where earthquakes strike is a random process, a scientific reality that often frustrates people who prefer patterns and having clues to warn before catastrophic events. The primary driving force behind earthquakes is the movement of tectonic plates.

In an interview in October, USGS research geophysicist Ken Hudnut explained why earthquakes are impossible to predict. To show how a fault gathers seismic stress that eventually ruptures into an earthquake, he showed a model of bricks sitting on sandpaper—equivalent to the two sides of the fault.

The bricks are attached to a rubber band connected to a handcrank, which, when it is moving, is like the accumulating seismic stress of plate tectonics. (In Southern California, the Pacific plate, where downtown L.A. sits, is moving northwest, while the North American plate is moving southeast.)

As Hudnut moved the handcrank, friction would keep the brick steady on the sandpaper, until at one point the accumulating force from the pulling rubber band was unbearable, and the brick would suddenly move—analogous to an earthquake. But when the movement happened wasn’t predictable. It was random.

There are other myths out there, such as the one in which hot, sunny “earthquake weather” somehow makes seismic events more likely; it doesn’t. Earthquakes happen underground, and the weather has no effect on their timing.

Hough said she decided to work on this study to rigorously test an idea that seismologists have long stated—that earthquakes aren’t more likely to happen on certain days of the calendar year or the cycle of the moon.

There are sometimes weird coincidences. For instance, in California, June 28 is the anniversary of a couple of memorable earthquakes: the magnitude 7.3 Landers earthquake that struck the Mojave Desert in 1992 (and the subsequent 6.5 Big Bear aftershock hours later); and the magnitude 5.6 Sierra Madre earthquake in 1991 that killed two people.

The next day, June 29, is the anniversary of the magnitude 6.8 Santa Barbara earthquake of 1925.

But those coincidences don’t mean anything.

“One analogy: if you had a classroom of 36 kids, on average, you’d expect to see three birthdays every month. You’d probably have a couple of kids on the exact same birthday,” Hough said, a result that does not hold some kind of larger meaning.

For her study, out of the more than 200 earthquakes she studied, if 20 or 30 of them happened on the full moon, “that would’ve actually been significant.” But that’s not what the results showed.

Note: The above post is reprinted from materials provided by Los Angeles Times, Distributed by Tribune Content Agency, LLC.

The Pentagon built with mineralized microbes predating dinosaurs

cross section of the ooids inside Rogenstein oolite
This is a cross section of the ooids inside Rogenstein oolite. Credit: ANU

A new study led by The Australian National University (ANU) has found that some of the building blocks of the Pentagon and Empire State Building were made by microbes that lived up to 340 million years ago, predating the dinosaurs.

The material, known as oolitic limestone, is a popular building material around the world and is almost completely made of millimetre-sized spheres of carbonate called ooids.

Co-researcher Dr Bob Burne from ANU said the new study found that ooids were made of concentric layers of mineralised microbes, debunking the popular ‘snowball theory’ that ooids were formed by grains rolling on the seafloor and accumulating layers of sediment.

“We have proposed a radically different explanation for the origin of ooids that explains their definitive features,” said

Dr Burne from the ANU Research School of Earth Sciences. “Our research has highlighted yet another vital role that microbes play on Earth and in our lives.”

Different types of oolitic limestones have formed in all geological periods and have been found around the world, including in the United States, the United Kingdom, Germany, the Bahamas, China and at Shark Bay in Western Australia.

Dr Burne said humans had known about and used oolitic limestone since ancient times.

“Many oolitic limestones form excellent building stones, because they are strong and lightweight,” he said.

“Mississippian oolite found in Indiana in the US has been used to build parts of the Pentagon in Virginia and parts of the Empire State Building in New York City.

“Jurassic oolite in England has been used to construct Buckingham Palace and much of the City of Bath, the British Museum and St Paul’s Cathedral.”

Professor Murray Batchelor from ANU led an international team of researchers on the study, which is published in Scientific Reports.

“Our mathematical model explains the concentric accumulation of layers, and predicts a limiting size of ooids,” said Professor Batchelor from the Research School of Physics and Engineering and the Mathematical Sciences Institute at ANU.

“We considered the problem theoretically using an approach inspired by a mathematical model developed in 1972 for the growth of some brain tumours.”

Professor Batchelor said the research findings could help better understand the effects of past climate change.

Reference:
Murray T. Batchelor, Robert V. Burne, Bruce I. Henry, Fei Li, Josef Paul. A biofilm and organomineralisation model for the growth and limiting size of ooids. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-017-18908-4

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

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