Amber piece showing most large inclusions Credit: NIGPAS
Most amber inclusions are organisms that lived in the forest. It is very rare to find sea life trapped in amber. However, an international research group led by Prof. Wang Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) reported the first known ammonite trapped in amber in a study in PNAS published on May 13.
The ammonite, a kind of sea animal, was trapped in 99-million-year-old amber from northern Myanmar. The amber is 33 mm long, 9.5 mm wide, 29 mm high and weighs 6.08 g. Besides the ammonite, the amber also encases a diverse assemblage of organisms that today live on land or in the sea, including at least 40 individual animals.
Of the terrestrial fauna found in the amber, mites are the most abundant. Also present are spiders, millipedes, cockroaches, beetles, flies and wasps, most of which would have lived on the forest floor.
Of the marine fauna, in addition to the ammonite itself, sea snails and sea slaters are present. The slaters are like those living on the seashore today.
The researchers used X-ray micro-computed tomography (micro-CT) to obtain high-resolution three-dimensional images of the ammonite including its convoluted sutures, which are important for identifying ammonites.
They found that the ammonite is a juvenile Puzosia (Bhimaites) and its presence in the amber supports a late Albian-early Cenomanian age for the amber deposit. This discovery represents a rare example of dating using amber inclusions.
But how on earth did the ammonite, an extinct sea-dwelling relative of squid, get preserved in a piece of amber that also contains land-based animals? The ammonite and sea snail shells offer possible clues.
The shells are all empty with no soft-tissue, so the organisms were long dead by the time they were engulfed by resin. The outer shell of the ammonite is broken away and the entrance of the shell is full of sand. The amber also contains additional sand.
The most likely explanation for the appearance of both marine and terrestrial organisms within the amber is that a sandy beach covered with shells was located close to resin-producing trees. The flying insects were trapped in the resin while it was still on the tree. As the resin flowed down the tree trunk, it trapped organisms that lived near the foot of the tree. Reaching the beach, it entombed shells and trapped the slaters living there.
The illustration shows the wing of Alcmonavis poeschli as it was found in the limestone slab. Alcmonavis poeschli is the second known specimen of a volant bird from the Jurassic period.
Archaeopteryx’s throne is tottering. Since the discovery of the first fossil of the primal bird in 1861, it had been considered the only bird from the Jurassic geological period. Today’s birds are thought to be direct descendants of carnivorous dinosaurs, with Archaeopteryx representing the oldest known flying representative of this lineage. All of the specimens that have been found up to now come from the region of the Solnhofen Archipelago, which during the Jurassic era spanned across what is today the Altmühl Valley, in the area between Pappenheim and Regensburg. Archaeopteryx lived here in a landscape of reef islands about 150 million years ago.
A team led by Professor Oliver Rauhut has taxonomically identified a bird unknown until now: Alcmonavis poeschli, the second bird from the era identified as capable of flight. “This suggests that the diversity of birds in the late Jurassic era was greater than previously thought,” says Rauhut, paleontologist at the Department of Earth and Environmental Sciences as well as the Bavarian State Collection of Paleontology and Geology.
Only a wing of Alcmonavis poeschli was discovered. “At first, we assumed that this was another specimen of Archaeopteryx. There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird,” says Rauhut. According to the team’s taxonomic studies, which are currently featured in the scientific journal eLife, Alcmonavis poeschli was not merely somewhat larger than Archaeopteryx; apparently it could also fly better. “The wing muscles indicate a greater capacity for flying,” says Rauhut. Alcmonavis poeschli exhibits numerous traits lacking in Archaeopteryx but present in more recent birds. This suggests that it was adapted better to active, flapping flight.
The discovery of Alcmonavis poeschli has implications for the debate over whether active flapping birds arose from gliding birds. “Its adaptation shows that the evolution of flight must have progressed relatively quickly,” says Dr. Christian Foth from the University of Fribourg (Switzerland), one of the co-authors of the study.
The bird now being described for the first time derives its name from the old Celtic word for the river Altmühl, Alcmona, and its discoverer Roland Pöschl, who leads the excavation at the Schaudiberg quarry close to Mörnsheim. A fossil of Archaeopteryx was also discovered in the same unit of limestones. The two primal birds thus apparently lived at the same time in what was then a subtropical lagoon landscape in southern Germany.
Reference:
Oliver WM Rauhut, Helmut Tischlinger, Christian Foth. A non-archaeopterygid avialan theropod from the Late Jurassic of southern Germany. eLife, 2019; 8 DOI: 10.7554/eLife.43789
When it comes to making a lasting impression in geological history, the medium makes all the difference, especially in the Earth’s paleo-oceans. Here, during the Archean Eon (4,000-2,500 million years ago) and at times during the Proterozoic (2,500-541 million years ago), when oxygen in the atmosphere and oceans was much lower than today, sedimentary minerals preserved signatures of biological activity in the form of fine textures created by microbial communities. The environmental conditions under which rocks like these form dictate how the crystal structure develops—the more orderly and fine-grained, the better the preservation.
Understanding, and better yet, replicating how these ancient minerals grew provides information about Earth’s past environments, and how organisms developed and behaved. One of these fossil-bearing rocks has proven difficult to copy in the lab—until now.
Researchers from MIT and Princeton University have found a way to emulate a part of ancient Earth in the lab by reproducing one of these weathering-resistant, information-carrying minerals, dolomite, whose formation has long perplexed scientists. A close relative to, and which can be created from, minerals that make limestone, dolomite was pervasive in the past; however, researchers rarely find it in modern environments. While it’s created from components commonly found in seawater, there are physical and kinetic barriers preventing the formation of dolomite—layers of carbonate (CO3-2) ions with alternating central atoms of calcium and magnesium. Alternatively, studies have reported protodolomite—a rock with a disordered crystalline structure, occurring only in very salty modern environments—but this mineral does not preserve the same fine microbial textures as its more ordered brother.
“To look for evidence of ancient life and old processes, you have to look at microbial structures. That’s where the information is. Some of that information is preserved in the form of very finely-grained dolomite, which precipitates almost as the microbes grow. It preserves the lamina of these microbial mats,” says Tanja Bosak, associate professor in the MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS) whose lab led the research. Her group uses experimental geobiology to explore modern biogeochemical and sedimentological processes in microbial systems and interpret the record of life on the early Earth. However, “there’s a big problem about the origin of finely-grained dolomite in a lot of microbial structures through time: There was no clear way of making dolomite under Earth’s surface conditions.”
Their results published in the journal Geology report the first creation of ordered dolomite and find that the trick to capturing these textures may be a slurry of manganese ions, seawater, light, and a biofilm of anaerobic, sulfur-metabolizing, photosynthetic microbes in an oxygen-free environment.
The study’s co-authors are former EAPS postdoc Mirna Daye and Associate Professor John Higgins from Princeton University.
Dolomite problem and the importance of order
Since the first identification of dolomite in the 18th century in what is now known as the Dolomite Mountains of Northern Italy, scientists have been stumped by how dolomite forms, and why there is so much ancient dolomite and so little of the mineral in modern times. This issue was dubbed “the dolomite problem.”
Scientists have found that modern dolomite can form in two main ways. It precipitates when shallow, hypersaline seawater is heated, and when limestone encounters magnesium-rich water, like a deep reef that’s invaded by seawater solutions. However, both methods make large crystals that obscure much of the biological information. In modern seawater, however, aragonite and calcite (different crystalline structures of calcium carbonate) are more likely to precipitate out than dolomite. “It’s not hard to make dolomite if you heat up a beaker of seawater to very high temperatures, but you’ll never get it at the Earth’s surface temperature and pressure just on its own,” says Bosak. “It’s really hard to get magnesium into the minerals; it doesn’t really want to go into the crystal lattice.” That’s a portion of the larger picture. Additionally, these mechanisms do not account for mineral variations (manganese or iron-rich dolomite) seen during the Archean and Proterozoic periods that preserved these textures. “You see that seawater is saturated with respect to dolomite, [but] it just doesn’t form, so there’s some kinetic barrier to that.”
It wasn’t until the turn of the 20th century that a Russian microbiologist demonstrated the potential for anaerobic bacteria to cause dolomite to form from minerals in ocean water, a process called biomineralization. Since then, researchers have found that in modern environments, biofilms—containing photosynthetic microbes and the slimy organic matrix that they excrete for their home (exopolymeric substances)—in highly evaporative pools of salty water can provide a surface on which dolomite can nucleate and grow. However, these biofilms are not photosynthetic. In contrast, many microbial structures that were preserved before the rise of oxygen grew in less-salty marine environments and are thought to have been produced by photosynthetic microbial communities. Additionally, the location of ions and microbes thought to be involved in this process likely differed in the past. The past microbes relied on sulfide, hydrogen, or iron ions for photosynthesis. Researchers suspect that more than 2 billion years ago, manganese and iron ions were present higher in the ocean sediments or even the water column. Today, because of the oxygenated atmosphere, they’re buried deeper in sediments where anaerobic conditions can occur. However, the lack of sunlight means that microbial mats don’t grow here, so neither does dolomite.
While the suggestion of microbial involvement was a strong step to solving the dolomite problem, the matters of crystal ordering and formation in the sunlit marine zone, where microbes colonize sediments, were still unresolved.
Reproducing the past
While investigating early sedimentological preservation, the group performed a series of experiments replicating the conditions of these ancient oceans with an anaerobic atmosphere. They used a combination of modern biofilms, light/dark environments, and seawater modified to mimic early Earth conditions with and without manganese, one of the metals often found in the mineral and thought to facilitate bacterial growth. The researchers used microbes from a lake in upstate New York, from depths that lack oxygen.
In their experiments, the researchers noticed something unexpected—that the most abundant mineral in the biofilms was highly ordered dolomite, and the vials that produced the most contained photosynthesizing microbes and manganese—a result consistent with field reports. As the mats grew up toward the light, crystals accumulated on them, with the oldest on the bottom capturing tiny wiggles where now degraded microbial mats used to be. The more extensive the coverage, the smaller the porosity, which reduced the chances of fluids infiltrating them, interacting with and dissolving the minerals, and essentially erasing data. The experiments lacking manganese or performed in the dark (not photosynthesizing) developed disordered dolomite. “We don’t understand exactly why manganese and the microbes have that effect, but it seems like they do. It’s almost like a natural consequence of those types of conditions,” says Bosak. Nonetheless, “It was a big deal to show that that can actually happen.”
Now that the team has found a way to make ordered dolomite, they plan to look into why it forms, variations, and how the rock records the environmental conditions it forms in. After seeing the effect that manganese had on dolomite, the researchers will look at iron ions, which integrated into these ancient rocks. “Iron also seems to stimulate the formation of the incorporation of magnesium into this mineral, for whatever reason,” says Bosak.
They’ll also investigate the unique microbial interactions and physical properties present to see what components are essential to precipitating dolomite. The individual niches that each anaerobic organism occupies seem to help the community grow, cycle elements, degrade substances, and provide a surface for crystals. The Bosak group will do this by fossilizing various organisms under the same or different environmental conditions to see if they can produce dolomite. During these experiments, they will monitor how well dolomite records the temperature at which it was made, as well as the chemical and isotopic composition of the surrounding solution, to understand the process better.
“I think it tells us that—when we are trying to interpret the past—it’s a really different planet: different types of organisms, different types of metabolisms that were dominant,” says Bosak, “and I think we are just starting to scratch the surface of what possible mineral outcomes, what kind of textural outcomes we can even expect.”
Reference:
Mirna Daye et al. Formation of ordered dolomite in anaerobic photosynthetic biofilms, Geology (2019). DOI: 10.1130/G45821.1
It is a diamond with the same mineral properties as colorless diamonds, displaying red color. They are commonly known as the world’s most expensive and rare color of diamonds, more so than pink diamonds or blue diamonds.
It is like pink diamonds, are highly debated as to the source of their color, but the gemological community most frequently attributes both colors to gliding atoms in the structure of the diamond as it undergoes tremendous pressure during its formation.
They are among the twelve colors of fancy diamonds, the most expensive per carat price. They usually run in the range of hundreds of thousands of dollars per carat. Because they are the rarest color, they are hard to find in large sizes and are mostly found in sizes below 1 carat.
It exist only with one intensity of colour, Fancy, although their clarity may vary from Flawless to Included, just like white diamonds. The biggest and most flawless red diamond is the Red Diamond 5.11 carat Fancy Red Moussaieff, which has flawless clarity internally.
Source of Red Color in Diamonds
The most widely accepted theory is that a plastic deformation is caused in the crystal lattice structure during the formation of the diamond. Some of the atoms are misplaced as the diamond moves through its deposit of kimberlite, and this movement’s intense pressure causes the different shades of pink or red to appear.
This credits the hypothesis that they are actually extremely dark pink diamonds and why only one intensity of color is possible. It can be modified by the same secondary colors that can also be found to modify pink diamonds.
Red color can be produced with high-energy particles irradiating a colorless diamond and then annealing it at high pressures and high temperatures.
Where Can Red Diamond be Found?
Red diamond source mines. Most of the them mined each year come from Kimberley, Western Australia’s Argyle diamond mine. They were also found in Brazil, Russia, and some African countries, though.
How Much Red Diamond?
In 1987, the first gem quality called the Hancock Red sold for over $926,000 per carat!
“Pure” red diamonds are so rare and disproportionately priced that they are generally beyond the scope of celebrity life and are rarely found above 1 Carat. As an example, this SI2 Clarity grade 0.71 Carat Fancy Red Diamond Radiant is priced at $ 603,600!
A Petoskey Stone is a rock and a fossil composed of a fossilized rugose coral, Hexagonaria percarinata, which is often pebble-shaped. Such stones were formed as a result of glaciation, where sheets of ice plucked stones from the bedrock, grinding off their rough edges and depositing them in the lower peninsula of Michigan’s northwest (and some in the northeast). Complete fossilized coral heads can be found in the source rocks for the Petoskey stones in the same areas of Michigan.
Petoskey stones are found in the Traverse Group’s Gravel Point Formation. They are fragments of an originally deposited coral reef during the Devonian period. When dry, the stone resembles ordinary calcareous but the distinctive mottled pattern of six-sided coral fossils emerges when wet or polished using lapidary techniques. It is sometimes turned into objects of decoration. There are also other forms of fossilized coral in the same location.
It was named Michigan’s state stone in 1965.
Where Is Petoskey Stone Found?
Petoskey stones can be found in Michigan on different beaches and inland locations, with many of the most popular being those around Petoskey and Charlevoix. During the winters, the frozen lake ice movement acting on the shore is thought to turn over stones at the shore of Lake Michigan, exposing new Petoskey stones at the edge of the water every spring.
Also present in the fossil records of Iowa, Indiana, Illinois, Ohio, New York and locations in Canada, Germany, England, and Asia is the type of coral that forms the basis of Petoskey Stones.
Subduction Zone. Credit: California Institute of Technology
It is well known that life on Earth and the geology of the planet are intertwined, but a new study provides fresh evidence for just how deep—literally—that connection goes. Geoscientists at Caltech and UC Berkeley have identified a chemical signature in igneous rocks recording the onset of oxygenation of Earth’s deep oceans—a signal that managed to survive the furnace of the mantle. This oxygenation is of great interest, as it ushered in the modern era of high atmospheric and oceanic oxygen levels, and is believed to have allowed the diversification of life in the sea.
Their findings, which were published in Proceedings of the National Academy of Science on April 11, support a leading theory about the geochemistry of island arc magmas and offer a rare example of biological processes on the planet’s surface affecting the inner Earth.
Island arcs are formed when one oceanic tectonic plate slides beneath another in a process called subduction. The subducting plate descends and releases water-rich fluids into the overlying mantle, causing it to melt and produce magmas that ultimately ascend to the surface of the earth. This process builds island arc volcanoes like those found today in the Japanese islands and elsewhere in the Pacific Ring of Fire. Eventually, through plate tectonics, island arcs collide with and are incorporated into continents, preserving them in the rock record over geological time.
The most abundant magmatic, or igneous, rocks are basalts—dark-colored and fine-grained rocks commonly found in lava flows. Most basalts on the earth today do not form at island arcs but rather at mid-ocean ridges deep underwater. A well-known difference between the two is that island arc basalts are more oxidized than those found at mid-ocean ridges.
A leading but debated hypothesis for this difference is that oceanic crust is oxidized by oxygen and sulfate in the deep ocean before it is subducted into the mantle, delivering oxidized material to the mantle source of island arcs above the subduction zone.
But Earth is not thought to have always had an oxygenated atmosphere and deep ocean. Rather, scientists believe, the emergence of oxygen—and with it the ability for the planet to sustain aerobic life—occurred in two steps. The first event, which took place between about 2.3 and 2.4 billion years ago, resulted in a greater than 100,000-fold increase in atmospheric O2 in the atmosphere, to about 1 percent of modern levels.
Although it was dramatically higher than it had previously been, the atmospheric O2 concentration at this time still was too low to oxygenate the deep ocean, which is thought to have remained anoxic until around 400 to 800 million years ago. Around that time, atmospheric O2 concentrations are thought to have increased to 10 to 50 percent of modern levels. That second jump has been proposed to have allowed oxygen to circulate into the deep ocean.
“If the reason why modern island arcs are fairly oxidized is due the presence of dissolved oxygen and sulfate in the deep ocean, then it sets up an interesting potential prediction,” says Daniel Stolper (Caltech Ph.D. ’14), one of the authors of the paper and an assistant professor of Earth and Planetary Science at UC Berkeley. “We know roughly when the deep oceans became oxygenated and thus, if this idea is right, one might see a change in how oxidized ancient island arc rocks were before versus after this oxygenation.”
To search for the signal of this oxygenation event in island arc igneous rocks, Stolper teamed up with Caltech assistant professor of geology Claire Bucholz, who studies modern and ancient arc magmatic rocks. Stolper and Bucholz combed through published records of ancient island arcs and compiled geochemical measurements that revealed the oxidation state of arc rocks that erupted tens of millions to billions of years ago. Their idea was simple: if oxidized material from the surface is subducted and oxidizes the mantle regions that source island arc rocks, then ancient island arc rocks should be less oxidized (and thus more “reduced”) than their modern counterparts.
“It’s not as common anymore, but scientists used to routinely quantify the oxidation state of iron in their rock samples,” Bucholz says. “So there was a wealth of data just waiting to be reexamined.”
Their analysis revealed a distinct signature: a detectable increase in oxidized iron in bulk-rock samples between 800 and 400 million years ago, the same time interval that independent studies proposed the oxygenation of the deep ocean occurred. To be thorough, the researchers also explored other possible explanations for the signal. For example, it is commonly assumed that the oxidation state of iron in bulk rocks can be compromised by metamorphic processes—the heating and compaction of rocks—or by processes that alter them at or near the surface of the earth. Bucholz and Stolper constructed a variety of tests to determine whether such processes had affected the record. Some alteration almost certainly occurred, Bucholz says, but the changes are consistent everywhere that samples were taken. “The amount of oxidized iron in the samples may have been shifted after cooling and solidification, but it appears to have been shifted in a similar way across all samples,” she says.
Stolper and Bucholz additionally compiled another proxy also thought to reflect the oxidation state of the mantle source of arc magmas. Reassuringly, this independent record yielded similar results to the iron-oxidation-state record. Based on this, the researchers propose that the oxygenation of the deep ocean impacted not only on the earth’s surface and oceans but also changed the geochemistry of a major class of igneous rocks.
This work complements earlier research by Bucholz that examines changes in the oxidation signatures of minerals in igneous rocks associated with the first oxygenation event 2.3 billion years ago. She collected sedimentary-type, or S-type, granites, which are formed during the burial and heating of sediments during the collision of two landmasses—for example, in the Himalayas, where the Indian subcontinent is colliding with Asia.
“The granites represent melted sediments that were deposited at the surface of Earth. I wanted to test the idea that sediments might still record the first rise of oxygen on Earth, despite having been heated up and melted to create granite,” she says. “And indeed, it does.”
Both studies speak to the strong connection between the geology of Earth and the life that flourishes on it, she says. “The evolution of the planet and of the life on it are intertwined. We can’t understand one without understanding the other,” says Bucholz.
The PNAS study is titled “Neoproterozoic to early Phanerozoic rise in island arc redox state due to deep ocean oxygenation and increased marine sulfate levels.”
Reference:
Daniel A. Stolper et al. Neoproterozoic to early Phanerozoic rise in island arc redox state due to deep ocean oxygenation and increased marine sulfate levels, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1821847116
a. Fossil; b. restoration, scale bar equal 10 mm; c. melanosomes of the membranous wing (mw); d. histology of the bony stomach content (bn). st, styliform element; gs, gastroliths Credit: WANG Min
A new Jurassic non-avian theropod dinosaur from 163 million-year-old fossil deposits in northeastern China provides new information regarding the incredible richness of evolutionary experimentation that characterized the origin of flight in the Dinosauria.
Drs. Wang Min, Jingmai K. O’Connor, Xu Xing, and Zhou Zhonghe from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences described and analyzed the well-preserved skeleton of a new species of Jurassic scansoriopterygid dinosaur with associated feathers and membranous tissues. Their findings were published in Nature.
The new species, named Ambopteryx longibrachium, belongs to the Scansoriopterygidae, one of the most bizarre groups of non-avian theropods. The Scansoriopterygidae differ from other theropods in their body proportions, particularly in the proportions of the forelimb, which supports a bizarre wing structure first recognized in a close relative of Ambopteryx, Yi qi.
Unlike other flying dinosaurs, namely birds, these two species have membranous wings supported by a rod-like wrist bone that is not found in any other dinosaur (but is present in pterosaurs and flying squirrels).
Until the discovery of Yi qi in 2015, such a flight apparatus was completely unknown among theropod dinosaurs. Due to incomplete preservation in the holotype and only known specimen of Yi qi, the veracity of these structures and their exact function remained hotly debated.
As the most completely preserved specimen to date, Ambopteryx preserves membranous wings and the rod-like wrist, supporting the widespread existence of these wing structures in the Scansoriopterygidae.
WANG and his colleagues investigated the ecomorphospace disparity of Ambopteryx relative to other non-avian coelurosaurians and Mesozoic birds. The results showed dramatic changes in wing architecture evolution between the Scansoriopterygidae and the avian lineage, as the two clades diverged and underwent very different evolutionary paths to achieving flight.
Interestingly, forelimb elongation, an important characteristic of flying dinosaurs, was achieved in scansoriopterygids primarily through elongation of the humerus and ulna, whereas the metacarpals were elongated in non-scansoriopterygid dinosaurs including Microraptor and birds.
In scansoriopterygids, the presence of an elongated manual digit III and the rod-like wrist probably compensated for the relatively short metacarpals and provided the main support for the membranous wings. In contrast, selection for relatively elongated metacarpals in most birdlike dinosaurs was likely driven by the need for increased area for the attachment of the flight feathers, which created the wing surface in Microraptor and birds.
The co-occurrence of short metacarpals with membranous wings, versus long metacarpals and feathered wings, exhibits how the evolution of these two significantly different flight strategies affected the overall forelimb structure. So far, all known scansoriopterygids are from the Late Jurassic and their unique membranous wing structure did not survive into the Cretaceous.
This suggests that this wing structure represents a short-lived and unsuccessful attempt to fly. In contrast, feathered wings, first documented in Late Jurassic non-avian dinosaurs, were further refined through the evolution of numerous skeletal and soft tissue modifications, giving rise to at least two additional independent origins of dinosaur flight and ultimately leading to the current success of modern birds.
Reference:
Min Wang et al. A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs, Nature (2019). DOI: 10.1038/s41586-019-1137-z
Reconstructed skull and lower jaw of Acherontiscus caledoniae
Micro-CT scanning of a tiny snake-like fossil discovered in Scotland has shed new light on the elusive creature, thought to be one of the earliest known tetrapods to develop teeth that allowed it to crush its prey.
Detailed scans of Acherontiscus caledoniae showed a unique combination of different tooth shapes and sizes as well as a deep lower jaw which scientists believe would have given the creature the ability to pierce, cut and grind the hard-shelled crustaceans that made up its diet.
Scientists led by the University Museum of Zoology in Cambridge alongside the University of Lincoln, the Natural History Museum in London and the University of Southampton, found that the dental pattern of Acherontiscus is at odds with that of several other tetrapods of this period, which tended to have uniform rows of cone-like teeth sometimes curved backwards at the tip. The variation in the shape and size of teeth shown in this fossil displays a level of dental adaptation that is unprecedented in such an early tetrapod.
As co-author Dr Marcello Ruta from the University of Lincoln’s School Of Life Sciences explains: “We found that Acherontiscus preceded the origin of modern tetrapod lineages and joined an array of primitive groups that independently acquired long and often miniaturized bodies, and exhibited either reduced or no limbs.”
The fossil is the only known specimen of this limbless tetrapod, which measured just 6 inches long and existed in swampy marshlands on the outskirts of Edinburgh some 330 million years ago. The delicate nature of the fossil meant that scientists were unable to use mechanical or chemical methods to free its skeleton from the surrounding rock, or study the specimen under a microscope.
Lead author Professor Jennifer Clack from the University Museum of Zoology in Cambridge said: “Using advanced techniques of micro-CT scanning, we were able to make sense of Acherontiscus’ complex skull, revealing minute anatomical details that allowed us to produce a greatly revised and much more complete reconstruction.
“We were particularly surprised to realize the great variety of shapes and sizes of its teeth. Acherontiscus is the earliest known tetrapod showing a crushing dentition, a feature with a rather discontinuous distribution in fossil and modern tetrapods.”
Fragments in the surrounding matrix have also revealed more about Acherontiscus’ habitat which will inform further research into the area as co-author Professor John Marshall from the University of Southampton’s School of Ocean and Earth Science explains: “Our study provided impetus for exploring the ecology and environments of the Scottish wetlands where Acherontiscus lived. Analysis of the content of fossil spores from about 0.2 grams of the matrix surrounding the creature suggests that this animal lived close to or within a still water body surrounded by herbaceous plants related to clubmosses. A more distant forest of larger, tree-like relatives of modern quillworts was also present.”
Reference:
Jennifer A. Clack, Marcello Ruta, Andrew R. Milner, John E. A. Marshall, Timothy R. Smithson, Keturah Z. Smithson. Acherontiscus caledoniae: the earliest heterodont and durophagous tetrapod. Royal Society Open Science, 2019; 6 (5): 182087 DOI: 10.1098/rsos.182087
Fossil casts of Australopithecus afarensis (left), Homo habilis (center), and Australopithecus sediba (right)
Statistical analysis of fossil data shows that it is unlikely that Australopithecus sediba, a nearly two-million-year-old, apelike fossil from South Africa, is the direct ancestor of Homo, the genus to which modern-day humans belong.
The research by paleontologists from the University of Chicago, published this week in Science Advances, concludes by suggesting that Australopithecus afarensis, of the famous “Lucy” skeleton, is still the most likely ancestor to the genus Homo.
The first A. sediba fossils were unearthed near Johannesburg in 2008. Hundreds of fragments of the species have since been discovered, all dating to roughly two million years ago. The oldest known Homo fossil, the jawbone of an as yet unnamed species found in Ethiopia, is 2.8 million years old, predating A. sediba by 800,000 years.
Despite this timeline, the researchers who discovered A. sediba have claimed that it is an ancestral species to Homo. While it is possible that A. sediba (the hypothesized ancestor) could have postdated earliest Homo (the hypothesized descendant) by 800,000 years, the new analysis indicates that the probability of finding this chronological pattern is highly unlikely.
“It is definitely possible for an ancestor’s fossil to postdate a descendant’s by a large amount of time,” said the study’s lead author Andrew Du, PhD, who will join the faculty at Colorado State University after concluding his postdoctoral research in the lab of Zeray Alemseged, PhD, the Donald M. Pritzker Professor of Organismal and Biology and Anatomy at UChicago.
“We thought we would take it one step further to ask how likely it is to happen, and our models show that the probability is next to zero,” Du said.
Du and Alemseged also reviewed the scientific literature for other hypothesized ancestor-descendant relationships between two hominin species. Of the 28 instances they found, only one first-discovered fossil of a descendant was older than its proposed ancestor, a pair of Homo species separated by 100,000 years, far less than the 800,000 years separating A. sediba and earliest Homo. For context, the average lifespan of any hominin species is about one million years.
“Again, we see that it’s possible for an ancestor’s fossil to postdate its descendant’s,” Du said. “But 800,000 years is quite a long time.”
Alemseged and Du maintain that Australopithecus afarensisis a better candidate for the direct ancestor of Homofor a number of reasons. A. afarensis fossils have been dated up to three million years old, nearing the age of the first Homo jaw. Lucy and her counterparts, including Selam, the fossil of an A. afarensischild that Alemseged discovered in 2000, were found in Ethiopia, just miles from where the Homo jaw was discovered. The jaw’s features also resemble those of A. afarensis closely enough that one could make the case it was a direct descendant.
“Given the timing, geography and morphology, these three pieces of evidence make us think afarensisis a better candidate than sediba,” Alemseged said. “One can disagree about morphology and the different features of a fossil, but the level of confidence we can put in the mathematical and statistical analyses of the chronological data in this paper makes our argument a very strong one.”
Reference:
Andrew Du and Zeresenay Alemseged. Temporal evidence shows Australopithecus sediba is unlikely to be the ancestor of Homo. Science Advances, 2019 DOI: 10.1126/sciadv.aav9038
David Stahle in North Carolina’s Black River. Photo by Dan Griffin.
A recently documented stand of bald cypress trees in North Carolina, including one tree at least 2,624 years old, are the oldest known living trees in eastern North America and the oldest known wetland tree species in the world.
David Stahle, Distinguished Professor of geosciences, along with colleagues from the university’s Ancient Bald Cypress Consortium and other conservation groups, discovered the trees in 2017 in a forested wetland preserve along the Black River south of Raleigh, North Carolina. Stahle documented the age of the trees using dendrochronology, the study of tree rings, and radio carbon dating. His findings were published May 9 in the journal Environmental Research Communications.
The ancient trees are part of an intact ecosystem that spans most of the 65-mile length of the Black River. In addition to their age, the trees are a scientifically valuable means of reconstructing ancient climate conditions. The oldest trees in the preserve extend the paleoclimate record in the southeast United States by 900 years, and show evidence of droughts and flooding during colonial and pre-colonial times that exceed any measured in modern times.
“It is exceedingly unusual to see an old-growth stand of trees along the whole length of a river like this,” Stahle said. “Bald cypress are valuable for timber and they have been heavily logged. Way less than 1 percent of the original virgin bald cypress forests have survived.”
Stahle has been working in the area since 1985, and cataloged bald cypress trees as old as 1,700 years in a 1988 study published in the journal Science. His work helped preserve the area, 16,000 acres of which have since been purchased by The Nature Conservancy, a private land-conservation group that keeps most of its holdings open to the public.
“Dr. Stahle’s original work on the Black River, which showed trees dating from Roman times, inspired us to begin conservation on the Black more than two decades ago,” said Katherine Skinner, executive director of The North Carolina Chapter of The Nature Conservancy. “This ancient forest gives us an idea of what much of North Carolina’s coastal plain looked like millennia ago. It is a source of inspiration and an important ecosystem. Without Dr. Stahle, it would have gone unprotected and likely destroyed.”
For the newest study, researchers used non-destructive core samples from 110 trees found in a section of the wetland forest they had not previously visited. “The area of old growth bald cypress was 10 times larger than I realized,” Stahle said. “We think there are older trees out there still.”
Reference:
D W Stahle, J R Edmondson, I M Howard, C R Robbins, R D Griffin, A Carl, C B Hall, D K Stahle, M C A Torbenson. Longevity, climate sensitivity, and conservation status of wetland trees at Black River, North Carolina. Environmental Research Communications, 2019; 1 (4): 041002 DOI: 10.1088/2515-7620/ab0c4a
Photographed on Kangaroo Island, this rock – called a ‘zebra schist’ – deformed from flat-lying marine sediments through being stressed by a continental collision over 500 million years ago. Credit: Dietmar Muller, CC BY
Zebra Schist is The tightly folded, thinly bedded schists that are derived from sedimentary rocks that are exposed in Kangaroo Island are known as zebra schists. A quartz-rich and biotite-rich layering largely reflects original sedimentary layering rather than metamorphic differentiation as the secondary biotite preserves and outlines a variety of sedimentary structures.
Small cross-beds troughs and climbing ripples show a sequence facing south. The Geological Society of Australia
has designated this section of the coastline as a geological monument.
Where is Zebra Schist found?
It Found in Harvey’s Return, Kangaroo Island, South Australia
What is Schist?
Schist is a metamorphic rock of medium grade. In a preferred orientation, Schist has medium to large, flat, sheet-like grains (nearby grains are approximately parallel). It is defined by having platy and elongated minerals (such as micas or talc) of more than 50 percent, often finely interleaved with quartz and feldspar.
These minerals include micas, chlorite, talc, hornblende, graphite, and other lamellar (flat, planar). In drawn-out grains, quartz often occurs to such an extent that a particular shape is produced called quartz schist. Often schist is garnetiferous. At a higher temperature, schist forms and has larger grains than phyllite. Geological foliation with medium to large grained flakes in a preferred sheetlike orientation is called schistosity (metamorphic arrangement in layers).
Zebra Schist
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Photographed on Kangaroo Island, this rock – called a ‘zebra schist’ – deformed from flat-lying marine sediments through being stressed by a continental collision over 500 million years ago. Credit: Dietmar Muller, CC BY
Photographed on Kangaroo Island, this rock – called a ‘zebra schist’ – deformed from flat-lying marine sediments through being stressed by a continental collision over 500 million years ago. Credit: Dietmar Muller, CC BY
A new study from The University of Texas at Austin looks at the complex geology that contributed to the 2010 Deepwater Horizon disaster. Credit: US Coast Guard
A study from The University of Texas at Austin is the first published in a scientific journal to take an in-depth look at the challenging geologic conditions faced by the crew of the Deepwater Horizon drilling rig and the role those conditions played in the 2010 disaster.
The well blowout killed 11 people and spewed oil for three months, spilling about 4 million barrels of oil into the Gulf of Mexico before crews successfully capped the well. Researchers and investigators since then have focused mostly on the engineering decisions and mistakes that led to the blowout and the ecological impacts of the oil spill that became one of the country’s worst environmental catastrophes. But researchers from the UT Jackson School of Geosciences, aided by thousands of pages of documents made public during lawsuits and legal proceedings, have pieced together how the geologic conditions more than 2 miles under the Gulf floor made drilling difficult and drove engineering decisions that contributed to the well’s failure and the ensuing blowout.
The study, published May 7 in Scientific Reports, documents, among other things, a significant and steep drop in pore pressure inside the rock near the bottom of the well that influenced the decisions that contributed to the blowout.
“The paper tells the geological story behind the catastrophe,” said Will Pinkston, who authored the paper while earning a master’s degree at the Jackson School. “It is high impact science, and I’m excited to reach a wider audience of people who don’t think about these issues every day.”
The engineering and geosciences challenges posed by drilling wells miles under the surface of the earth are enormously complex. One of the most critical is to maintain the pressure within the well so that it is higher than the pressure within the fluid inside the rock but lower than the stress at which the rock fails. If pressure inside the well is too high, it will fracture the well wall and drive drilling fluids into the rock. If the well pressure is lower than the rock’s fluid pressure, fluids from inside the surrounding rock will flow into the well and potentially cause a blowout.
To successfully drill, crews use drilling “mud,” a slurry that can be mixed to varying weights and consistency, which is circulated throughout the well to help stabilize the hole and control pressure. Crews then line the exposed well with cement and steel casing to seal off exposed rock.
In the case of the Transocean Deepwater Horizon drilling rig, which was operated by the BP energy company at the time of the accident, the pore pressure was very high throughout the well, but then dropped abruptly by about 1,200 pounds per square inch near the bottom. Most of the pore pressure drop occurred in the 100 feet above the reservoir target of 18,000 feet below sea level.
BP planned to temporarily abandon the oil well, the initial well in the Macondo prospect, until it could be produced at a later date, by plugging the base with steel and cement. However, the sharp drop in pore pressure, and an associated decline in stress, drastically narrowed the range of options to seal off the well. This led to the decision to use a controversial low-density foam cement that failed to set properly. This was a key cause of the Macondo well blowout.
“The bottom line is that the geological conditions led to a decision to use a specialized cement that failed,” said Peter Flemings, a Jackson School professor and study author. “This decision was a root cause of the ultimate blowout.”
Flemings was a member of the Deepwater Horizon well integrity team assembled by then-U.S. Energy Secretary Steven Chu to help respond to the disaster.
Beyond describing the pressure and stress conditions in the well, the paper maps geologic conditions across the entire subterranean basin to show that the pressure drop is not a unique event in that area.
“Macondo isn’t a one-dimensional problem,” Pinkston said. “We found evidence of large-scale fluid connectivity across the basin, and this would have been hard to predict.”
Although the paper does not pinpoint any single reason for the catastrophe, Flemings said it offers important information for the larger drilling community.
“One of the significant things about this paper is to get all the data on the table so that the general community can understand the decisions that were made,” Flemings said.
“I broadly believe that if engineers and geoscientists are more aware of how pressure and stress and engineering decisions couple, better decisions will be made.”
The study was funded by Flemings and the UT GeoFluids consortium. Data from the consortium and the University of Texas Institute for Geophysics Gulf Basin Depositional Synthesis project were used in this study. BP is one of the companies that supports the consortium.
Reference:
F. William M. Pinkston, Peter B. Flemings. Overpressure at the Macondo Well and its impact on the Deepwater Horizon blowout. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-42496-0
Radioactive carbon released into the atmosphere from 20th-century nuclear bomb tests has reached the deepest parts of the ocean, new research finds.
A new study in AGU’s journal Geophysical Research Letters finds the first evidence of radioactive carbon from nuclear bomb tests in muscle tissues of crustaceans that inhabit Earth’s ocean trenches, including the Mariana Trench, home to the deepest spot in the ocean.
Organisms at the ocean surface have incorporated this “bomb carbon” into the molecules that make up their bodies since the late 1950s. The new study finds crustaceans in deep ocean trenches are feeding on organic matter from these organisms when it falls to the ocean floor. The results show human pollution can quickly enter the food web and make its way to the deep ocean, according to the study’s authors.
“Although the oceanic circulation takes hundreds of years to bring water containing bomb [carbon] to the deepest trench, the food chain achieves this much faster,” said Ning Wang, a geochemist at the Chinese Academy of Sciences in Guangzhou, China, and lead author of the new study.
“There’s a very strong interaction between the surface and the bottom, in terms of biologic systems, and human activities can affect the biosystems even down to 11,000 meters, so we need to be careful about our future behaviors,” said Weidong Sun, a geochemist at the Chinese Academy of Sciences in Qingdao, China, and co-author of the new study. “It’s not expected, but it’s understandable, because it’s controlled by the food chain.”
The results also help scientists better understand how creatures have adapted to living in the nutrient-poor environment of the deep ocean, according to the authors. The crustaceans they studied live for an unexpectedly long time by having extremely slow metabolisms, which the authors suspect may be an adaptation to living in this impoverished and harsh environment.
Creating radioactive particles
Carbon-14 is radioactive carbon that is created naturally when cosmic rays interact with nitrogen in the atmosphere. Carbon-14 is much less abundant than non-radioactive carbon, but scientists can detect it in nearly all living organisms and use it to determine the ages of archeological and geological samples.
Thermonuclear weapons tests conducted during the 1950s and 1960s doubled the amount of carbon-14 in the atmosphere when neutrons released from the bombs reacted with nitrogen in the air. Levels of this “bomb carbon” peaked in the mid-1960s and then dropped when atmospheric nuclear tests stopped. By the 1990s, carbon-14 levels in the atmosphere had dropped to about 20 percent above their pre-test levels.
This bomb carbon quickly fell out of the atmosphere and mixed into the ocean surface. Marine organisms that have lived in the decades since this time have used bomb carbon to build molecules within their cells, and scientists have seen elevated levels of carbon-14 in marine organisms since shortly after the bomb tests began.
Life at the bottom of the sea
The deepest parts of the ocean are the hadal trenches, those areas where the ocean floor is more than 6 kilometers (4 miles) below the surface. These areas form when one tectonic plate subducts beneath another. Creatures that inhabit these trenches have had to adapt to the intense pressures, extreme cold, and lack of light and nutrients.
In the new study, researchers wanted to use bomb carbon as a tracer for organic material in hadal trenches to better understand the organisms that live there. Wang and her colleagues analyzed amphipods collected in 2017 from the Mariana, Mussau, and New Britain Trenches in the tropical West Pacific Ocean, as far down as 11 kilometers (7 miles) below the surface. Amphipods are a type of small crustacean that live in the ocean and get food from scavenging dead organisms or consuming marine detritus.
Surprisingly, the researchers found carbon-14 levels in the amphipods’ muscle tissues were much greater than levels of carbon-14 in organic matter found in deep ocean water. They then analyzed the amphipods’ gut contents and found those levels matched estimated carbon-14 levels from samples of organic material taken from the surface of the Pacific Ocean. This suggests the amphipods are selectively feeding on detritus from the ocean surface that falls to the ocean floor.
Adapting to the deep ocean environment
The new findings allow researchers to better understand the longevity of organisms that inhabit hadal trenches and how they have adapted to this unique environment.
Interestingly, the researchers found the amphipods living in these trenches grow larger and live longer than their counterparts in shallower waters. Amphipods that live in shallow water typically live for less than two years and grow to an average length of 20 millimeters (0.8 inches). But the researchers found amphipods in the deep trenches that were more than 10 years old and had grown to 91 millimeters (3.6 inches) long.
The study authors suspect the amphipods’ large size and long life are likely the byproducts of their evolution to living in the environment of low temperatures, high pressure and a limited food supply. They suspect the animals have slow metabolisms and low cell turnover, which allows them to store energy for long periods of time. The long life time also suggests pollutants can bioaccumulate in these unusual organisms.
“Besides the fact that material mostly comes from the surface, the age-related bioaccumulation also increases these pollutant concentrations, bringing more threat to these most remote ecosystems,” Wang said.
The new study shows deep ocean trenches are not isolated from human activities, Rose Cory, an associate professor of earth and environmental sciences at the University of Michigan who was not involved in the new research, said in an email. The research shows that by using “bomb” carbon, scientists can detect the fingerprint of human activity in the most remote, deepest depths of the ocean, she added.
The authors also use “bomb” carbon to show that the main source of food for these organisms is carbon produced in the surface ocean, rather than more local sources of carbon deposited from nearby sediments, Cory said. The new study also suggests that the amphipods in the deep trenches have adapted to the harsh conditions in deep trenches, she added.
“What is really novel here is not just that carbon from the surface ocean can reach the deep ocean on relatively short timescales, but that the ‘young’ carbon produced in the surface ocean is fueling, or sustaining, life in the deepest trenches,” Cory said.
Reference:
Ning Wang, Chengde Shen, Weidong Sun, Ping Ding, Sanyuan Zhu, Weixi Yi, Zhiqiang Yu, Zhongli Sha, Mei Mi, Lisheng He, Jiasong Fang, Kexin Liu, Xiaomei Xu, Ellen R.M. Druffel. Penetration of Bomb 14 C into the Deepest Ocean Trench. Geophysical Research Letters, 2019; DOI: 10.1029/2018GL081514
The calving front of Bowdoin Glacier in northwestern Greenland, where icebergs are discharged and ice under the water melts. Credit: Photo taken by Shin Sugiyama
In recent years, glaciers near the North and South poles, as well as in mountainous areas, have been shrinking due to the effect of global warming, becoming a significant contributor to the recent sea level rise. Calving glaciers, which discharge icebergs into an ocean or lake, have retreated more rapidly than those on land because of sections collapsing at the glacier front and due to submarine melting.
It is, however, difficult to directly measure the volume of calving ice and submarine melting because conducting on-site examinations at the glacier front can be dangerous. Conventional methods that measure their volume based on satellite image analysis also yield only low temporal and spatial resolutions and do not allow continuous monitoring.
When icebergs break off into water, the so-called impulse waves or simply, tsunami waves, move over the ocean or lake. In this study, the team including Evgeny Podolskiy and Shin Sugiyama of Hokkaido University and Masahiro Minowa of the Austral University of Chile measured the volume of icebergs that broke off from Bowdoin Glacier, a calving glacier terminating at the head of Bowdoin Fjord. An underwater pressure sensor capable of making 20 measurements per second was placed in front of the glacier to record calving-generated tsunami waves measuring 10 centimeters to 1 meter high. The researchers then compared the data with high-resolution images of the glacier front taken by unmanned aerial vehicles (UAVs) as well as images by a time-lapse camera to find the relationship between calving events and tsunami-wave properties.
The team found a positive correlation between the volume of calving ice and wave amplitude, and confirmed that the distance to calving events can be measured with a single pressure sensor from a frequency dispersion of water waves. Based on their measurements, they estimated the temporal and spatial distribution of icebergs that broke off within the study period from Bowdoin Glacier. The estimated volume of calving ice was also compared with the speed the glacier was flowing, the tides, and fluctuations in air temperature.
The team found that the calving volume was higher at places where meltwater rises from the bottom of the glacier to the sea surface. The calving volume, or rate, was greater during periods of fast ice flow, high air temperature, and at falling/low tide. A satellite image analysis showed calving events caused only 20 percent of the mass loss at the glacier front, suggesting 80 percent of the ice mass loss was caused by submarine melting.
“Our study, which utilized tsunami signals to measure the calving flux, will help us understand the interplay between glaciers and oceans, a key factor in predicting future evolutions of glaciers,” says Evgeny Podolskiy.
The study was led by Masahiro Minowa and was conducted in collaboration with Austral University of Chile, ETH Zurich and the University of Florence.
It is a green forest, olive green or blue green vitreous silica projectile rock formed by a meteorite impact in southern Germany (Nördlinger Ries Crater) occurring around 15 million years ago. It’s a kind of tectitis.
Crystal system: Amorphous Color: Forest green Luster: Vitreous
What is Moldavite Made Of?
It was believed to have been formed after a meteorite impact by condensed rock vapors. It is part of the mineral group Tektite, a small family of natural glass rocks. Moldavite is sometimes claimed to be’ the only known alien gemstone on Earth’ or’ the gemstone born from the stars.’
How Moldavite is Formed?
According to the generally accepted theory, moldavites were formed during an impact of a huge meteorite 14.75 million years ago at high pressures and temperatures from superficial tertiary sediments in the Ries area of Germany.
What is Moldavite Worth?
The value of these Moldavites jumped from about USD 5 per gram about 20 years ago to about USD 75 and even up to USD 130 per gram today. The availability is extremely low and some Asian laboratories have perfected their production to provide the market with a very good look-alike man-made “Moldovite” glass.
Moldavite Gemstone
Moldavite Color
It occurs in a variety of shades of green, including deep, forest-green and pale to olive-green. Some materials from Moravia are known to occur with greenish-brown color. The most desirable color is a pure, light to medium green with no brown, and not too dark in tone.
Moldavite Clarity and Luster
It can be opaque and transparent. The finest specimens are transparent and very rare. Today’s most moldavite is opaque with slight translucency levels. Generally speaking, the higher the transparency, the better the stone. There is a big difference in price between moldavite’ regular grade’ and museum grade.
Moldavite Cut and Shape
It comes in a variety of shapes and cuts. Only the finest and most transparent materials are faced, while the rest are usually traded in their natural rough condition. The most common shapes are those resulting from its molten formation, such as drop shape, disk shape, oval, elliptical or spiral shape, as well as shapes that resemble spilled liquid patterns. Bohemian moldavite is usually drop-shaped, while spherical is Moravian moldavite.
Where Moldavite is Found?
Moldavite’s largest deposits were found in the upper Vltava River basin between Prachatice and Trhovými Sviny, particularly in the south and west of the Czech Republic of České Budějovice (Budweis). Also found in Moravia, mainly in the Jihlava river’s central area.
Reconstruction of the tyrannosauroid Suskityrannus hazelae from the Late Cretaceous (~92 million years ago) in current day New Mexico. Credit: Andrey Atuchin
A new relative of the Tyrannosaurus rex — much smaller than the huge, ferocious dinosaur made famous in countless books and films, including, yes, “Jurassic Park” — has been discovered and named by a Virginia Tech paleontologist and an international team of scientists.
The newly named tyrannosauroid dinosaur — Suskityrannus hazelae — stood roughly 3 feet tall at the hip and was about 9 feet in length, the entire animal only marginally longer than the just the skull of a fully grown Tyrannosaurus rex, according to Sterling Nesbitt, an assistant professor with Department of Geosciences in the Virginia Tech College of Science. In a wild twist to this discovery, Nesbitt found the fossil at age 16 whilst a high school student participating in a dig expedition in New Mexico in 1998, led by Doug Wolfe, an author on the paper.
In all, Suskityrannus hazelae is believed to have weighed between 45 and 90 pounds. The typical weight for a full-grown Tyrannosaurus rex is roughly 9 tons. Its diet likely consisted of the same as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting small animals, although what it hunted is unknown. The dinosaur was at least 3 years old at death based on an analysis of its growth from its bones.
The fossil dates back 92 million years to the Cretaceous Period, a time when some of the largest dinosaurs ever found lived.
“Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet,” Nesbitt said. “It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the latest Cretaceous that include some of the most famous dinosaurs, such as the Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmotosaurus.”
The findings are published in the latest online issue of Nature Ecology & Evolution. In describing the new find, Nesbitt said, “Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex. The find also links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.
(Tyrannosaurus rex small arm jokes abound. So, if you’re wondering how small the arms of Suskityrannus were, Nesbitt and his team are not exactly sure. No arm fossils of either specimen were found, but partial hand claws were found. And, they are quite small. Also not known: If Suskityrannus had two or three fingers.)
Two partial skeletons were found. The first included a partial skull that was found in 1997 by Robert Denton, now a senior geologist with Terracon Consultants, and others in the Zuni Basin of western New Mexico during an expedition organized by Zuni Paleontological Project leader Doug Wolfe.
The second, more complete specimen was found in 1998 by Nesbitt, then a high school junior with a burgeoning interest in paleontology, and Wolfe, with assistance in collection by James Kirkland, now of the Utah Geological Survey. “Following Sterling out to see his dinosaur, I was amazed at how complete a skeleton was lying exposed at the site,” Kirkland said.
For much of the 20 years since the fossils were uncovered, the science team did not know what they had.
“Essentially, we didn’t know we had a cousin of Tyrannosaurus rex for many years,” Nesbitt said. He added the team first thought they had the remains of a dromaeosaur, such as Velociraptor. During the late 1990s, close relatives Tyrannosaurus rex simply were not known or not recognized. Since then, more distant cousins of Tyrannosaurus rex, such as Dilong paradoxus, have been found across Asia.
The fossil remains were found near other dinosaurs, along with the remains of fish, turtles, mammals, lizards, and crocodilians. From 1998 until 2006, the fossils remain stored at the Arizona Museum of Natural History in Mesa, Arizona. After 2006, Nesbitt brought the fossils with him through various postings as student and researcher in New York, Texas, Illinois, and now Blacksburg. He credits the find, and his interactions with the team members on the expedition, as the start of his career.
“My discovery of a partial skeleton of Suskityrannus put me onto a scientific journey that has framed my career,” said Nesbitt, also a member of the Virginia Tech Global Change Center. “I am now an assistant professor that gets to teach about Earth history.”
The name Suskityrannus hazelae is derived from “Suski,” the Zuni Native American tribe word for “coyote,” and from the Latin word ‘tyrannus’ meaning king and ‘hazelae’ for Hazel Wolfe, whose support made possible many successful fossil expeditions in the Zuni Basin. Nesbitt said permission was granted from the Zuni Tribal Council to use the word “Suski.”
Reference:
Sterling J. Nesbitt, Robert K. Denton Jr, Mark A. Loewen, Stephen L. Brusatte, Nathan D. Smith, Alan H. Turner, James I. Kirkland, Andrew T. McDonald & Douglas G. Wolfe. A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology & Evolution, 2019 DOI: 10.1038/s41559-019-0888-0
A laser-heated diamond anvil cell is used to simulate the pressure and temperature conditions of Earth’s core. Inset shows a scanning electron miscroscope image of a quenched melt spot with immiscible liquids. Credit: Sarah M. Arveson/Yale University
A Yale-led team of scientists may have found a new factor to help explain the ebb and flow of Earth’s magnetic field—and it’s something familiar to anyone who has made a vinaigrette for their salad.
Earth’s magnetic field, produced near the center of the planet, has long acted as a buffer from the harmful radiation of solar winds emanating from the Sun. Without that protection, life on Earth would not have had the opportunity to flourish. Yet our knowledge of Earth’s magnetic field and its evolution is incomplete.
In a new study published May 6 in the Proceedings of the National Academy of Sciences, Yale associate professor Kanani K.M. Lee and her team found that molten iron alloys containing silicon and oxygen form two distinct liquids under conditions similar to those in the Earth’s core. It is a process called immiscibility.
“We observe liquid immiscibility often in everyday life, like when oil and vinegar separate in salad dressing. It is surprising that liquid phase separation can occur when atoms are being forced very close together under the immense pressures of Earth’s core,” said Yale graduate student Sarah Arveson, the study’s lead author.
Immiscibility in complex molten alloys is common at atmospheric pressure and has been well documented by metallurgists and materials scientists. But studies of immiscible alloys at higher pressures have been limited to pressures found in Earth’s upper mantle, located between Earth’s crust and its core.
Even deeper, 2,900 kilometers beneath the surface, is the outer core—a more than 2,000-kilometer thick layer of molten iron. It is the source of the planet’s magnetic field. Although this hot liquid roils vigorously as it convects, making the outer core mostly well-mixed, it has a distinct liquid layer at the top. Seismic waves moving through the outer core travel slower in this top layer than they do in the rest of the outer core.
Scientists have offered several theories to explain this slow liquid layer, including the idea that immiscible iron alloys form layers in the core. But there has been no experimental or theoretical evidence to prove it until now.
Using laser-heated, diamond-anvil cell experiments to generate high pressures, combined with computer simulations, the Yale-led team reproduced conditions found in the outer core. They demonstrated two distinct, molten liquid layers: an oxygen-poor, iron-silicon liquid and an iron-silicon-oxygen liquid. Because the iron-silicon-oxygen layer is less dense, it rises to the top, forming an oxygen-rich layer of liquid.
“Our study presents the first observation of immiscible molten metal alloys at such extreme conditions, hinting that immiscibility in metallic melts may be prevalent at high pressures,” said Lee.
The researchers said the findings add a new variable for understanding conditions of the early Earth, as well as how scientists interpret changes in Earth’s magnetic field throughout history.
Additional authors of the study are Jie Deng of Yale and Bijaya Karki of Louisiana State University.
Fossilized giant arthropod Phytophilaspis from the Cambrian Period. Credit: Andrey Zhuravlev, Lomonosov Moscow State University
Extreme fluctuations in atmospheric oxygen levels corresponded with evolutionary surges and extinctions in animal biodiversity during the Cambrian explosion, finds new study led by UCL and the University of Leeds.
The Cambrian explosion was a crucial period of rapid evolution in complex animals that began roughly 540 million years ago. The trigger for this fundamental phase in the early history of animal life is a subject of ongoing biological debate.
The study, published today in Nature Geoscience by scientists from the UK, China and Russia, gives strong support to the theory that oxygen content in the atmosphere was a major controlling factor in animal evolution.
The study is the first to show that during the Cambrian explosion there was significant correlation between surges in oxygen levels and bursts in animal evolution and biodiversity, as well as extinction events during periods of low oxygen.
Dr Tianchen He, study lead author and postdoctoral researcher at the University of Leeds, began this research while at UCL. He said: “The complex creatures that came about during the Cambrian explosion were the precursors to many of the modern animals we see today. But because there is no direct record of atmospheric oxygen during this time period it has been difficult to determine what factors might have kick started this crucial point in evolution.
“By analysing the carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth’s atmosphere and shallow oceans during the Cambrian Explosion. When compared to fossilised animals from the same time we can clearly see that evolutionary radiations follow a pattern of ‘boom and bust’ in tandem with the oxygen levels.
“This strongly suggests oxygen played a vital role in the emergence of early animal life.”
Study co-author Professor Graham Shields from UCL Earth Sciences, said: “This is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels.
“The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period. In that time, Earth went from being populated by simple, single-celled and immobile organisms to hosting the wonderful variety of intricate, energetic life forms we see today.”
The team analysed the carbon and sulphur isotopes from marine carbonate samples collected from sections along the Aldan and Lena rivers in Siberia. During the time of the Cambrian explosion this area would have been a shallow sea and the home for the majority of animal life on Earth.
The lower Cambrian strata in Siberia are composed of continuous limestone with rich fossil records and reliable age constraints, providing suitable samples for the geochemical analyses. The isotope signatures in the rocks relate to the global production of oxygen, allowing the team to determine oxygen levels present in the shallow ocean and atmosphere during the Cambrian Period.
Study co-author Dr Benjamin Mills, from the School of Earth and Environment at Leeds, said: “The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian explosion.
“Combining our isotope measurements with a mathematical model lets us track the pulses of carbon and sulphur entering the sediments in this critical evolutionary cradle. Our model uses this information to estimate the global balance of oxygen production and destruction, giving us new insight into how oxygen shaped the life we have on the planet today.”
Study co-author Maoyan Zhu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, said: “Understanding what triggered the Cambrian explosion requires multidisciplinary study. That’s why with Graham Shields we organized together such a multidisciplinary team funded by NERC and NSFC in past years. I am so excited about the results through this collaborative project.”
“On the other hand, it took a long time to get this result. We already got samples from Siberia in 2008. The sections in Siberia are difficult to access. It took time for us to organize the expedition and collect the samples there. Without support from Russian colleagues, we could not do the project.”
Study co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University said: “This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen.”
Reference:
Tianchen He, Maoyan Zhu, Benjamin J. W. Mills, Peter M. Wynn, Andrey Yu. Zhuravlev, Rosalie Tostevin, Philip A. E. Pogge von Strandmann, Aihua Yang, Simon W. Poulton and Graham A. Shields. Possible links between extreme oxygen perturbations and the Cambrian radiation of animals. Nature Geoscience, 2019 DOI: 10.1038/s41561-019-0357-z
Note: The above post is reprinted from materials provided by University of Leeds.
Representative Image: Dinosaur. Credit: Public Domain
A study conducted between the UPV/EHU-University of the Basque Country and the University of Zaragoza has conducted an in-depth analysis of the dinosaur fossils at La Cantalera-1, one of the Iberian sites belonging to the Lower Cretaceous with the largest number of vertebrates. The structure of the fossilized bone tissue as well as the fossilization processes have been studied. It has been possible to confirm that most of the dinosaurs found at La Cantalera-1 were young individuals.
The site at La Cantalera-1 is located in Teruel (Spain) and regarded as hugely important by the scientific community, as it is one of the sites on the Iberian Peninsula with the greatest diversity of vertebrates of the Lower Cretaceous. Remains of dinosaurs, mammals, crocodiles, pterosaurs, lizards, tortoises, amphibians and fish dating back to approximately 130 million years ago have been discovered. A multidisciplinary study carried out by researchers in the Department of Stratigraphy and Palaeontology and the Department of Mineralogy and Petrology at the UPV/EHU’s Faculty of Science and Technology, together with the University of Zaragoza (Aragosaurus-IUCA Group), has explored not only the fossilization process (taphonomy) which took place in some of these remains, but also the internal structure displayed by the bones (palaeohistology).
The site has undergone thorough investigation. “No previous investigation had tackled it from these perspectives or with the depth that we have conducted in this study,” said Leire Perales-Gogenola, a member of the UPV/EHU’s Department of Stratigraphy and Palaeontology and lead author of the paper.
For their work, they selected two groups of dinosaurs: ornithopods (of which there are abundant remains at the site), and ankylosaurs (known as armoured dinosaurs as they had armour consisting of bony plates). Although large fossils exist, this research group resorted to “fragmentary remains, small pieces of bone and the dermal bones. The methodology we had to follow involved making sections in the samples and we did not want to damage the more important items,” said the researcher.
Wetland ecosystem with a wealth of young individuals
The study of the internal structures of the fossil bones (palaeohistology) “revealed that most of the ornithopod dinosaurs were young individuals. On inspecting the fossilized bones under the microscope, they were found to display the same structure as unfossilized bones as they retain all their characteristics. This enables us to identify the signs that tell us whether they belonged to adult or immature individuals; it is possible to know, for example, whether the individual in question was a large but young dinosaur or whether it was a small but adult dinosaur,” explained the UPV/EHU biologist and palaeontologist.
In the study of the internal part of the dermal bones they observed “various traces that other researchers had associated with a specific group of ankylosaurs, so in some cases we were able to determine more accurately what kind of dinosaurs they were.”
For the taphonomic study, the researcher emphasized the usefulness of analysing fragmentary remains, “as they are bones that have undergone fractures owing to the pressure of the subsequent burial itself, among other things, and this has allowed various sedimentary materials to filter through these fractures, which have been fossilized beside the bone remains; this provides hugely valuable information about the environment in which they were found.” In this part of the study, they were able to deduce that these bones were subjected to rapid burial, and soon reached the phreatic level in which the fossilization processes had already taken place. Microbial activity in the bones, the presence of bacterial forming microbial carpets, has also been detected, and this may have encouraged the fossilization process.
The results have increased the available knowledge about the site. “The features of the ecosystem and degree of maturity of the individuals present, which had already been described in previous studies, have been confirmed. The data indicate that it was a wetland ecosystem and was used as a feeding zone for the fauna in the area. Due to the wealth of young individuals and eggshell remains, which are also very abundant at the site, it has been suggested that it could have been a breeding or feeding area,” said Perales-Gogenola.
Forthcoming studies at the site anticipated by the University of Zaragoza are due to tackle the palaeohistology of the dinosaurs present at La Cantalera-1 and also to go further into the age of death of the herbivore dinosaurs to certify whether it was a natural population or whether there is an excessive number of youngsters owing to predation issues by theropod dinosaurs (carnivorous dinosaurs that could attack young individuals more frequently than adult individuals).
Reference:
Leire Perales-Gogenola et al, Taphonomy and palaeohistology of ornithischian dinosaur remains from the Lower Cretaceous bonebed of La Cantalera (Teruel, Spain), Cretaceous Research (2019). DOI: 10.1016/j.cretres.2019.01.024
USGS map highlights earthquake risk zones. Blue boxes indicate areas of high activity of human-caused earthquake due to deep bore fluid injection. Credit: USGS
Using data from field experiments and modeling of ground faults, researchers at Tufts University have discovered that the practice of subsurface fluid injection used in ‘fracking‘ and wastewater disposal for oil and gas exploration could cause significant, rapidly spreading earthquake activity beyond the fluid diffusion zone. Deep fluid injections — greater than one kilometer deep — are known to be associated with enhanced seismic activity — often thought to be limited to the areas of fluid diffusion. Yet the study, published today in the journal Science, tests and strongly supports the hypothesis that fluid injections are causing potentially damaging earthquakes further afield by the slow slip of pre-existing fault fracture networks, in domino-like fashion.
The results account for the observation that the frequency of human-made earthquakes in some regions of the country surpass natural earthquake hotspots.
The study also represents a proof of concept in developing and testing more accurate models of fault behavior using actual experiments in the field. Much of our current understanding about the physics of geological faults is derived from laboratory experiments conducted at sample length scales of a meter or less. However, earthquakes and fault rupture occur over vastly larger scales. Observations of fault rupture at these larger scales are currently made remotely and provide poor estimates of the physical parameters of fault behavior that would be used to develop a model of human-made effects. More recently, the earthquake science community has put resources behind field-scale injection experiments to bridge the scale gap and understand fault behavior in its natural habitat.
The researchers used data from these experimental field injections, previously conducted in France and led by a team of researchers based at the University of Aix-Marseille and the University of Nice Sophia-Antipolis. The experiments measured fault pressurization and displacement, slippage and other parameters that are fed into the fault-slip model used in the current study. The Tufts researchers’ analysis provides the most robust inference to date that fluid-activated slippage in faults can quickly outpace the spread of fluid underground.
“One important constraint in developing reliable numerical models of seismic hazard is the lack of observations of fault behavior in its natural habitat,” said Pathikrit Bhattacharya, a former post-doc in the department of civil and environmental engineering at Tufts University’s School of Engineering and lead author of the study. “These results demonstrate that, when available, such observations can provide remarkable insight into the mechanical behavior of faults and force us to rethink their hazard potential.” Bhattacharya is now assistant professor in the School of Earth, Ocean and Climate Sciences at the Indian Institute of Technology in Bhubaneswar, India.
The hazard posed by fluid-induced earthquakes is a matter of increasing public concern in the US. The human-made earthquake effect is considered responsible for making Oklahoma — a very active region of oil and gas exploration — the most productive seismic region in the country, including California. “It’s remarkable that today we have regions of human-made earthquake activity that surpass the level of activity in natural hot spots like southern California,” said Robert C. Viesca, associate professor of civil and environmental engineering at Tufts University’s School of Engineering, co-author of the study and Bhattacharya’s post-doc supervisor. “Our results provide validation for the suspected consequences of injecting fluid deep into the subsurface, and an important tool in assessing the migration and risk of induced earthquakes in future oil and gas exploration.”
Most earthquakes induced by fracking are too small — 3.0 on the Richter scale — to be a safety or damage concern. However, the practice of deep injection of the waste products from these explorations can affect deeper and larger faults that are under stress and susceptible to fluid induced slippage. Injection of wastewater into deep boreholes (greater than one kilometer) can cause earthquakes that are large enough to be felt and may cause damage.
According to the U.S. Geological Survey, the largest earthquake induced by fluid injection and documented in the scientific literature was a magnitude 5.8 earthquake in September 2016 in central Oklahoma. Four other earthquakes greater than 5.0 have occurred in Oklahoma as a result of fluid injection, and earthquakes of magnitude between 4.5 and 5.0 have been induced by fluid injection in Arkansas, Colorado, Kansas and Texas.
Reference:
Pathikrit Bhattacharya, Robert C. Viesca. Fluid-induced aseismic fault slip outpaces pore-fluid migration. Science, 2019; 364 (6439): 464 DOI: 10.1126/science.aaw7354
Note: The above post is reprinted from materials provided by Tufts University.
