Tag Archives: #dinosaurs

Dinosaurs Lived in Greenhouse Climate With Hot Summers (Paleontology)

New climate reconstruction method provides precise picture of climate 78 million years ago

Palaeoclimatologists study climate of the geological past. Using an innovative technique, new research by an international research team led by Niels de Winter (VUB-AMGC & Utrecht University) shows for the first time that dinosaurs had to deal with greater seasonal differences than previously thought.

De Winter: “We used to think that when the climate warmed like it did in the Cretaceous period, the time of the dinosaurs, the difference between the seasons would decrease, much like the present-day tropics experience less temperature difference between summer and winter. However, our reconstructions now show that the average temperature did indeed rise, but that the temperature difference between summer and winter remained rather constant. This leads to hotter summers and warmer winters.”

To better characterize the climate during this period of high CO2 concentration, the researchers used very well-preserved fossils of mollusks that lived in southern Sweden during the Cretaceous period, about 78 million years ago. Those shells grew in the warm, shallow seas that covered much of Europe at the time. They recorded monthly variations in their environment and climate, like the rings in a tree. For their research, de Winter and the team used the “clumped isotope” method for the first time, in combination with a method developed by Niels de Winter.

Clumped isotopes in combination with the VUB-UU method – a revolution in geology

Isotopes are atoms of the same element with different masses. Since the 1950s, the ratio of oxygen isotopes in carbonate has been used to measure water temperature in the geological past. However, this required researchers to estimate the chemistry of the seawater, as the isotope ratio of the seawater affects the isotope ratio of the shell, which results in higher uncertainty. About ten years ago, the “clumped isotope” method was developed, which does not depend on the chemistry of the seawater and allows accurate reconstructions. But the clumped isotope method has a disadvantage: it requires so much carbonate that temperature reconstructions at a more detailed level, such as seasonal fluctuations based on shells, were not possible.

De Winter has now developed an innovative method in which measurements of much smaller quantities of carbonate are cleverly combined for temperature reconstructions. The clumped isotope method thus requires much less material and can therefore be used for research on fossil shells, which, like tree rings, hold a great deal of information about their living conditions. The method also allows carbonate from successive summers (and winters) to be aggregated for better reconstruction of seasonal temperatures. For example, Winter found that water temperatures in Sweden during the Cretaceous “greenhouse period” fluctuated between 15°C and 27°C, over 10°C warmer than today.

The team also worked with scientists from the University of Bristol (UK) who develop climate models to compare the results with climate simulations of the Cretaceous period. Whereas previous climate reconstructions of the Cretaceous often came out colder than these models, the new results agree very well with the Bristol models. This shows that variations in seasons and water chemistry are very important in climate reconstructions:

“It is very difficult to determine climate changes from so long ago on the seasonal scale, but the seasonal scale is essential to get climate reconstructions right. If there is hardly any difference between the seasons, reconstructions of average annual temperature come out differently from situations when difference between the seasons is large. It was thought that during the age of the dinosaurs difference between the seasons was small. We have now established that there were greater seasonal differences. With the same temperature average over a year, you end up with a much higher temperature in the summer.

De Winter: “Our results therefore suggest that in the mid latitudes, seasonal temperatures will likely rise along with climate warming, while seasonal difference is maintained. This results in very high summer temperatures. The results bring new insight into the dynamics of a warm climate on a very fine scale, which can be used to improve both climate reconstructions and climate predictions. Moreover, they show that a warmer climate can also have extreme seasons.”

The development has far-reaching implications for the way climate reconstructions are done. It allows researchers to determine both the effect of seawater chemistry and that of differences between summer and winter, thus verifying the accuracy of decades of temperature reconstructions. For his groundbreaking research, De Winter has been nominated for both the annual EOS Pipette Prize and New Scientist Science Talent 2021.

The study by de Winter and colleagues appeared in the journal Communications in Earth and Environment on June 10th.

Featured image: Niels de Winter doing research on fossil shells © Niels de Winter

Reference: de Winter, N.J., Müller, I.A., Kocken, I.J. et al. Absolute seasonal temperature estimates from clumped isotopes in bivalve shells suggest warm and variable greenhouse climate. Commun Earth Environ 2, 121 (2021). https://doi.org/10.1038/s43247-021-00193-9

Provided by VUB

Dinosaurs That Hunted in the Dark (Paleontology)

The tiny desert-living dinosaur Shuvuuia had extraordinary vision and owl-like hearing for nocturnal life in the Mongolian desert

Today’s 10,000 species of birds live in virtually every habitat on Earth, but only a handful have adaptations enabling them to hunt active prey in the dark of night. Scientists have long wondered whether theropod dinosaurs – the group that gave rise to modern birds – had similar sensory adaptations.

A new study led by University of the Witwatersrand scientist, Professor Jonah Choiniere, sought to investigate how vision and hearing abilities of dinosaurs and birds compared. The international team of researchers used CT scanning and detailed measurements to collect information on the relative size of the eyes and inner ears of nearly 100 living bird and extinct dinosaur species.

Shuvuuia deserti artist’s reconstruction 2 © Viktor Radermaker

To measure hearing, the team measured the length of the lagena, the organ that processes incoming sound information (called the cochlea in mammals). The barn owl, which can hunt in complete darkness using hearing alone, has the proportionally longest lagena of any bird.

To assess vision, the team looked at the scleral ring, a series of bones surrounding the pupil, of each species. Like a camera lens, the larger the pupil can open, the more light can get in, enabling better vision at night. By measuring the diameter of the ring, the scientists could tell how much light the eye can gather.

The team found that many carnivorous theropods such as Tyrannosaurus and Dromaeosaurus had vision optimized for the daytime, and better-than-average hearing presumably to help them hunt. However, a diminutive theropod named Shuvuuia, part of a group known as alvarezsaurs, had both extraordinary hearing and night vision. The extremely large lagena of this species is almost identical in relative size to today’s barn owl, suggesting that Shuvuuia could have hunted in complete darkness.

The large lagena of Shuvuuia came as a surprise discovery to Dr. James Neenan, the joint first author of the study, and Choiniere’s former post-doc at Wits. “As I was digitally reconstructing the Shuvuuia skull, I couldn’t believe the lagena size…I called Prof. Choiniere to have a look. We both thought it might be a mistake, so I processed the other ear – only then did we realise what a cool discovery we had on our hands!” I couldn’t believe what I was seeing when I got there – dinosaur ears weren’t supposed to look like that!, “said Choiniere.

Prof. Jonah Choiniere holding a 3D printed model of the lagena of Shuvuuia deserti © Wits University

The eyes of Shuvuuia were also of note, as they had some of the proportionally largest pupils yet measured in birds or dinosaurs, suggesting that they could likely see very well at night.

Shuvuuia was a small dinosaur, about the size of a chicken, and it lived in the deserts of what is now Mongolia. Shuvuuia’s skeleton is among the most bizarre of all dinosaurs – it has a fragile, bird-like skull, brawny, weightlifter arms with a single claw on each hand, and long, roadrunner-like legs. This odd combination of features has baffled scientists since its discovery in the 1990s. With the new data on Shuvuuia’s senses, the scientific team hypothesizes that, like many desert animals, Shuvuuia would have foraged at night, using its hearing and vision to find prey like small mammals and insects, using its long legs to rapidly run that prey down, and using its strong forelimbs to pry the prey out of burrows or shrubby vegetation.

“Nocturnal activity, digging ability, and long hind limbs are all features of animals that live in deserts today,” said Choiniere, “but it’s surprising to see them all combined in a single dinosaur species that lived more than 65 million years ago.”

Featured image: Shuvuuia deserti artist’s reconstruction 1 © Viktor Radermaker

Reference: Jonah N. Choiniere, James M. Neenan et al., “Evolution of vision and hearing modalities in theropod dinosaurs”, Science  07 May 2021: Vol. 372, Issue 6542, pp. 610-613 DOI: 10.1126/science.abe7941

Provided by University of Witwatersrand

How Did Dinosaurs Deliver Bone-crushing Bites? By Keeping A Stiff Lower Jaw (Paleontology)

New research addresses longstanding mystery on the anatomy of the Tyrannosaurus rex jaw

Tyrannosaurus rex dinosaurs chomped through bone by keeping a joint in their lower jaw steady like an alligator, rather than flexible like a snake, according to a study being presented at the American Association for Anatomy annual meeting during the Experimental Biology (EB) 2021 meeting, held virtually April 27-30.

The research sheds new light on a conundrum that has perplexed paleontologists. Dinosaurs had a joint in the middle of their lower jaws, called the intramandibular joint, which is also present in modern-day reptiles. Previous research has suggested this joint was flexible, like it is in snakes and monitor lizards, helping carnivorous dinosaurs to keep struggling prey in their jaws. However, it has been unclear whether the jaws were flexible at all, or how they could be strong enough to bite through and ingest bone, which Tyrannosaurus did regularly, according to fossil evidence.

“We discovered that these joints likely were not flexible at all, as dinosaurs like T. rex possess specialized bones that cross the joint to stiffen the lower jaw,” said John Fortner, a doctoral student in anatomy at the University of Missouri, first author of the study.

Fortner and colleagues used CT scans of dinosaur fossils and modern reptiles to build a detailed 3D model of the T. rex jaw. Unlike previous models, their simulations include bone, tendons and specialized muscles that wrap around the back of the jaw, or mandible.

“We are modeling dinosaur jaws in a way that simply has not been done before,” said Fortner. “We are the first to generate a 3D model of a dinosaur mandible which incorporates not only an intramandibular joint, but also simulates the soft tissues within and around the jaw.”

To determine whether the intramandibular joint could maintain flexibility under the forces required to crunch through bone, the team ran a series of simulations to calculate the strains that would occur at various points depending on where the jaw hinged. The results suggest bone running along the inside of the jaw, called the prearticular, acted as a strain sink to counteract bending at the intramandibular joint, keeping the lower jaw stiff.

The team plans to apply their modeling approach to other dinosaur species in order to further elucidate biting mechanics among dinosaurs — and perhaps, help researchers better understand today’s creatures, as well.

“Because dinosaur mandibles are actually built so much like living reptiles, we can use the anatomy of living reptiles to inform how we construct our mandible models,” said Fortner. “In turn, the discoveries we make about T. rex’s mandible can provide more clarity on the diversity of feeding function in today’s reptiles like crocodilians and birds.”

Fortner will present this research in poster R3068 (abstract). This work will be featured in a virtual press conference from 1-1:45 p.m. EDT on Monday, April 26 (RSVP by Friday, April 23). Contact the media team for more information or to obtain a free press pass to access the virtual meeting.

Featured image: The researchers used CT scans of dinosaur fossils and modern-day specimens to create a 3D computer model of a dinosaur jaw and identify where muscles attach to bone. They then used the model to simulate muscle forces under different biting scenarios. Stars indicate areas where strain was assessed. © Image courtesy of John Fortner, University of Missouri.

Provided by Experimental Biology

Researcher Questions Whether Powered Flight Appeared on Non-avialan Dinosaurs (Paleontology)

Francisco Serrano, from University of Malaga, refutes this conclusion published in 2020 in the absence of scientific evidence

Powered flight in animals -that uses flapping wings to generate thrust- is a very energetically demanding mode of locomotion that requires many anatomical and physiological adaptations. In fact, the capability to develop it has only appeared four times in the evolutionary history of animals: on insects, pterosaurs, birds and bats.

A research paper published in 2020 in the scientific journal Current Biology concluded that, apart from birds -the only living descendants of dinosaurs-, powered flight would have originated independently in other three groups of dinosaurs. A conclusion that makes a great impact, as it increases the number of vertebrates that would have developed this costly mode of locomotion, which, among dinosaurs, would no longer be an exclusive capability of birds.

The scientist of the Department of Ecology and Geology of the University of Malaga Francisco Serrano Alarcón has recently published an article in the same journal, questioning the idea that powered flight appeared multiple times among dinosaurs.

Imagen at the Beijing Museum of Natural History, China. © Stephanie Abramowicz (Natural History Museum of Los Angeles County).

The researcher of the UMA, member of the Dinosaur Institute (NHMLAC) of Los Angeles, refutes such conclusion in the absence of scientific evidence. As he remarks, the parameters used by the authors to determine flight capability do not allow differentiation between powered flight and passive flight, the latter being frequent in many more animal groups.

This new study, which he conducted along with the paleontologist Luis M. Chiappe, Vice-President for Research and Collections of the NHMLAC, compares the parameters measured on present animals with powered flight capability, such as birds and bats, and gliding animals, for example, flying squirrels or flying reptiles, among others. Moreover, they added new data on the capability to generate energy from muscles in addition to the data considered in the original study.

“Birds are a group of dinosaurs of which we have discovered 150-million-year-old fossils with fully developed wings. Among their closest non-avialan relatives, we have also found fossils with sufficiently developed wings that could provide them with some aerodynamic benefit, whether to glide between trees or get thrust to climb and jump over obstacles. But this does not mean that they could take off by flapping their wings or maintain a powered flight”, explains Francisco Serrano.

In short, both authors conclude that, although they cannot discount the possibility that powered flight appeared in other non-avialan dinosaurs, current evidence does not support the hypothesis suggested in the original paper by Pei et al (2020).

Featured image: Imagen at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing © F.J. Serrano. University of Malaga

Reference: FJ Serrano, LM Chiappe. 2021. Independent origins for powered flight in paravian dinosaurs? Current Biology 31(8), R370-R372, 2021. DOI: https://doi.org/10.1016/j.cub.2021.03.058 Link to paper

Provided by University of Malaga

Short duration of the Yixian Formation and ‘Chinese Dinosaurs Pompeii’ (Paleontology)

The Early Cretaceous Jehol Biota, renowned for its exceptionally well preserved volcanic-influenced ecosystem, was buried in lacustrine and occasionally fluvial sediments in northern Hebei and western Liaoning, China. It includes large amount of evolutionarily significant taxonomy, e.g. feathered dinosaurs, early birds, mammals and flowering plants, representing one of the most diversified terrestrial biotas of the Mesozoic and providing exceptional windows into some major fundamental issues in earth and biological sciences, such as the origins of birds and angiosperm, and co-evolution of life and environments.

The evolutionary radiation of the Jehol Biota can be broadly divided to three phases, with the first phase limited to a small area in northern Hebei (Huajiying Formation), the second phase expanding to western Liaoning (Yixian Formation), and the third phase (Jiufotang Formation). Specifically, the Yixian Formation marks the greatest bio-diversification, and the Lujiatun Unit in its lowermost part preserves numerous three-dimensional dinosaurs fossils with gesture, often referred to as “Chinese Dinosaurs Pompeii” (Fig. 1). It is therefore crucial to precisely determine the timing and duration of the Yixian Formation. Despite considerable efforts in the past two decades attempting to achieve this goal, the published results (Fig. 2) are inconsistent, confusing and inadequate. The duration of the Yixian Formations and the relative temporal and stratigraphical sequences between Lujiatun (LJT) and Jiahsangou (JSG) Units remained controversial until recently.

Supported by the National Natural Science Foundation and Chinese Academy of Sciences, a group led by Prof. Yi-Gang Xu from the Guangzhou Institute of Geochemistry, CAS, in collaboration with Prof. Qing-Zhu Yin’s team at the University of California at Davis has carried out high-precision geochronology study on the Yixian Formation, using U-Pb chemical abrasion-isotope dilution-isotope ratio mass spectrometry (CA-ID-IRMS) dating technique with a typical analytical precision <0.05%. They extracted mineral zircon (ZrSiO4) grains from volcanic tuff layers collected from the top, middle and bottom of the Yixian Formation in the Jin-Yang basin, Liaoning, China. The results show the onset at 125.755 ± 0.061 Ma and termination at 124.122 ± 0.048 Ma of the Yixian Formation, respectively. The age of the top of the Lujiatun Unit is 125.684 ± 0.060 Ma, distinguishable from that of the Jianshangou Unit of lacustrine deposits (125.457 ± 0.051 Ma (Fig. 2).

Literature (black and white circles) and newly acquired ages (red) of the Yixian Formation ©Science China Press

These new ages have significant implications at several fronts.

(1) The duration of the Yixian Formation is tightly bracketed to 1.633 ± 0.078 Myr in Jin-Yang basin, significantly shorter than the previous broad range estimates of ~2 – 7 Myr, lending strong supports to a rapid bio-diversification during this period.

(2) The ages of the Lujiatun and Jianshangou units are resolvable, with the latter being sequentially deposited later than the former, therefore arguing against the idea of synchronous deposition of the two units spatially. Moreover, the extraordinarily short duration of Lujiatun Unit <71 ± 86 Kyr supports a sudden nature of the deposition event(s) linked with dramatic volcano-pyroclastic flows.

(3) The refined duration of the Yixian Formation also yields important insights on the duration of the JSG lacustrine deposits. It effectively rules out that the lacustrine cyclostratigraphy documented in part of the Yixian Formation was driven by orbital eccentricity, but more likely obliquity or precession signals. To interpret the observed 2 m cycle as 100 Kyr eccentricity cycle for a 41 m JSG Unit would mean the Jianshangou Unit alone would last >2 Myr, whereas the entire Yixian Formation, which include JSG Unit within it, lasted only 1.633 Myr, according to this study. The result makes sense in that when the temporal resolution is high, we expect to see precession signal to be most pronounced. This is because the Earth’s precession change contributes the most to the insolation that ultimately drive hydro-climate changes in Milankovitch cycles.

Featured image: Cluster of six juvenile Psittacosaurus from Lujiatun Unit (Zhao et al., 2013, Nature Communications, DOI: 10.1038/ncomms3079)

See the article:

Zhong et al. High-Precision Geochronological Constraints on the Duration of ‘Dinosaurs Pompeii’ and the Yixian Formation. National Science Review 2021, nwab063. https://doi.org/10.1093/nsr/nwab063

Provided by Science China Press

New Study Investigates How Life on Land Recovered After “The Great Dying” (Paleontology)

By characterizing how ancient life responded to environmental stressors, researchers gain insights into how modern species might fare.

Over the course of Earth’s history, several mass extinction events have destroyed ecosystems, including one that famously wiped out the dinosaurs. But none were as devastating as “The Great Dying,” which took place 252 million years ago during the end of the Permian period. A new study, published today in Proceedings of the Royal Society B, shows in detail how life recovered in comparison to two smaller extinction events. The international study team—composed of researchers from the China University of Geosciences, the California Academy of Sciences, the University of BristolMissouri University of Science and Technology, and the Chinese Academy of Sciences—showed for the first time that the end-Permian mass extinction was harsher than other events due to a major collapse in diversity.

To better characterize “The Great Dying,” the team sought to understand why communities didn’t recover as quickly as other mass extinctions. The main reason was that the end-Permian crisis was much more severe than any other mass extinction, wiping out 19 out of every 20 species. With survival of only 5% of species, ecosystems had been destroyed, and this meant that ecological communities had to reassemble from scratch.

To investigate, lead author and Academy researcher Yuangeng Huang, now at the China University of Geosciences, Wuhan, reconstructed food webs for a series of 14 life assemblages spanning the Permian and Triassic periods. These assemblages, sampled from north China, offered a snapshot of how a single region on Earth responded to the crises. “By studying the fossils and evidence from their teeth, stomach contents, and excrement, I was able to identify who ate whom,” says Huang. “It’s important to build an accurate food web if we want to understand these ancient ecosystems.”

After The Great Dying, the ecosystem changed drastically, and included many Lystrosaurus. © Xiaochong Guo

The food webs are made up of plants, molluscs, and insects living in ponds and rivers, as well as the fishes, amphibians, and reptiles that eat them. The reptiles range in size from that of modern lizards to half-ton herbivores with tiny heads, massive barrel-like bodies, and a protective covering of thick bony scales. Sabre-toothed gorgonopsians also roamed, some as large and powerful as lions and with long canine teeth for piercing thick skins. When these animals died out during the end-Permian mass extinction, nothing took their place, leaving unbalanced ecosystems for ten million years. Then, the first dinosaurs and mammals began to evolve in the Triassic. The first dinosaurs were small—bipedal insect-eaters about one meter long—but they soon became larger and diversified as flesh- and plant-eaters.

“Yuangeng Huang spent a year in my lab,” says Peter Roopnarine, Academy Curator of Geology. “He applied ecological modelling methods that allow us to look at ancient food webs and determine how stable or unstable they are. Essentially, the model disrupts the food web, knocking out species and testing for overall stability.”

“We found that the end-Permian event was exceptional in two ways,” says Professor Mike Benton from the University of Bristol. “First, the collapse in diversity was much more severe, whereas in the other two mass extinctions there had been low-stability ecosystems before the final collapse. And second, it took a very long time for ecosystems to recover, maybe 10 million years or more, whereas recovery was rapid after the other two crises.”

By the end of the Permian, pareiasaurs had become large and armored for self-protection. This complex ecosystem collapsed during The Great Dying. © Xiaochong Guo

Ultimately, characterizing communities—especially those that recovered successfully—provides valuable insights into how modern species might fare as humans push the planet to the brink.

“This is an amazing new result,” says Professor Zhong-Qiang Chen of the China University of Geosciences, Wuhan. “Until now, we could describe the food webs, but we couldn’t test their stability. The combination of great new data from long rock sections in north China with cutting-edge computational methods allows us to get inside these ancient examples in the same way we can study food webs in the modern world.”

Featured image: The plant-eating pareiasaurs were preyed upon by sabre-toothed gorgonopsians. Both groups went extinct during The Great Dying. © Xiaochong Guo

Provided by California Academy of Sciences

About Research at the California Academy of Sciences

The Institute for Biodiversity Science and Sustainability at the California Academy of Sciences is at the forefront of efforts to understand two of the most important topics of our time: the nature and sustainability of life on Earth. Based in San Francisco, the Institute is home to more than 100 world-class scientists, state-of-the-art facilities, and nearly 46 million scientific specimens from around the world. The Institute also leverages the expertise and efforts of more than 100 international Associates and 450 distinguished Fellows. Through expeditions around the globe, investigations in the lab, and analysis of vast biological datasets, the Institute’s scientists work to understand the evolution and interconnectedness of organisms and ecosystems, the threats they face around the world, and the most effective strategies for sustaining them into the future. Through innovative partnerships and public engagement initiatives, they also guide critical sustainability and conservation decisions worldwide, inspire and mentor the next generation of scientists, and foster responsible stewardship of our planet.

An Epic Walk: 15 Million Years Needed For Dinosaurs To Get From South America to Greenland (Paleontology)

For the first time, two researchers—one from the University of Copenhagen and the other from Columbia University—have accurately dated the arrival of the first herbivorous dinosaurs in East Greenland. Their results demonstrate that it took the dinosaurs 15 million years to migrate from the southern hemisphere, as a consequence of being slowed down by extreme climatic conditions. Their long walk was only possible because as CO2 levels dropped suddenly, the Earth’s climate became less extreme.

A snail could have crawled its way faster. 10,000 km over 15 million years—that’s how long it took the first herbivorous dinosaurs to make their way from Brazil and Argentina all the way to East Greenland. This, according to a new study by Professor Lars Clemmensen of the University of Copenhagen’s Department of Geosciences and Natural Resource Management and researcher Dennis Kent of New York’s Columbia University.

The herbivorous dinosaurs first appeared in Brazil and Argentina roughly 230 million years ago. This was during the early part of the Late Triassic period, the Norian, when the world consisted of one supercontinent called Pangæa, without any seas in between. The supercontinent allowed dinosaurs to disperse, unhindered from south to north. So, what took them so long to get to Greenland?

Professor Lars Clemmensen from University of Copenhagen and Nils Natorp from Geocenter Møns Klint on expedition in Greenland  © KU

The answer lies in unique rock deposits consisting of a 350-meter-long unbroken layer series of fossil sediments with bones from about 10 herbivorous dinosaurs that the researchers found on expeditions in East Greenland, and for which Lars Clemmensen and Dennis Kent have now made an accurate dating of.

Drastic fall in atmospheric CO2 levels

Using studies of these ancient sedimentary deposits to help them, the two researchers were able to see that the herbivorous dinosaurs reached East Greenland exactly 214 million years ago. Interestingly, their timing coincides with a major climatic shift that most probably helped them move along. The event? A drastic decrease in atmospheric CO2 levels 215 million years ago.

-“We are able to see that during the period leading up to the dinosaurs’ migration, there was ten times as much CO2 in the atmosphere than there is today. This made it difficult for them to disperse from their original habitat in the southern hemisphere, as higher levels of CO2 produce more extreme climatic conditions. The desert areas they needed to traverse were excruciatingly hot and dry and the humid equatorial areas were tremendously unstable and wet. As such, climate was most likely a barrier that delayed the dinosaurs’ northbound dispersion,” explains Professor Lars Clemmensen from the Department of Geosciences and Natural Resource Management.

The dating was performed using magnetostratigraphic studies. Here, the researchers read the Earth’s ancient magnetic fields in ancient lake deposits and compare them to similar, well-dated sedimentary sea deposits from elsewhere in the world. Even on a global scale, the researchers’ access to a 350-meter thick unbroken layered series of fossils which includes early herbivorous dinosaurs and other contemporaneous vertebrates is extraordinarily unique. The unbroken layer series has allowed them to accurately read changes in Earth’s ancient magnetic fields and made dating the layers safe.

Carnivorous dinosaurs were 600,000 years faster

Herbivorous dinosaurs weren’t alone in East Greenland, which at the time was at the same latitude as the northeastern United States. Therefore, the area had a humid temperate climate.  Small carnivorous dinosaurs had also made their way there. According to the researcher duo, the fossil finds in East Greenland and elsewhere also demonstrate that carnivorous dinosaurs were better at overcoming extreme climate barriers and migrating to new lands compared to their herbivorous relatives. The researchers’ preliminary analyses show that the meat eaters reached East Greenland 600,000 years before herbivorous dinosaurs.

Lars Clemmensen, along with Danish, European and American researchers, has been on seven expeditions. Along the way, he has taken part in the work of discovering bones not only from herbivorous dinosaurs, but from carnivorous dinosaurs, flying lizards, labyrinthodontia and early mammals. The new dating method makes it possible to precisely determine their ages:

“With this new and very precise chronology, we have a tool to better understand the dispersal pattern of many early vertebrates on Pangæa. This holds especially true in the area between Northern Europe and East Greenland. We can go into every layer of soil where we have found bones and precisely determine their age,” says Lars Clemmensen.

The research results are published in PNAS.

Reference: Dennis V. Kent, Lars B. Clemmensen, “Northward dispersal of dinosaurs from Gondwana to Greenland at the mid-Norian (215–212 Ma, Late Triassic) dip in atmospheric pCO2”, Proceedings of the National Academy of Sciences Feb 2021, 118 (8) e2020778118; DOI: 10.1073/pnas.2020778118

Provided by University of Copenhagen

Pioneering Prehistoric Landscape Reconstruction Reveals Early Dinosaurs Lived on Tropical Islands (Paleontology)

A new study using leading edge technology has shed surprising light on the ancient habitat where some of the first dinosaurs roamed in the UK around 200 million years ago.

The research, led by the University of Bristol, examined hundreds of pieces of old and new data including historic literature vividly describing the landscape as a “landscape of limestone islands like the Florida Everglades” swept by storms powerful enough to “scatter pebbles, roll fragments of marl, break bones and teeth.”

The evidence was carefully compiled and digitised so it could be used to generate for the first time a 3D map showing the evolution of a Caribbean-style environment, which played host to small dinosaurs, lizard-like animals, and some of the first mammals.

“No one has ever gathered all this data before. It was often thought that these small dinosaurs and lizard-like animals lived in a desert landscape, but this provides the first standardised evidence supporting the theory that they lived alongside each other on flooded tropical islands,” said Jack Lovegrove, lead author of the study published today in Journal of the Geological Society.

The study amassed all the data about the geological succession as measured all round Bristol through the last 200 years, from quarries, road sections, cliffs, and boreholes, and generated a 3D topographic model of the area to show the landscape before the Rhaetian flood, and through the next 5 million years as sea levels rose.

At the end of the Triassic period the UK was close to the Equator and enjoyed a warm Mediterranean climate. Sea levels were high, as a great sea, the Rhaetian Ocean, flooded most of the land. The Atlantic Ocean began to open up between Europe and North America causing the land level to fall. In the Bristol Channel area, sea levels were 100 metres higher than today.

Map of the Triassic palaeo-islands of the Bristol area. Includes silhouettes of the animals that lived on the islands and swam in the sea surrounding them. © Produced by paper authors. Thecodontosaurus silhouette based on the Bob Nicholls/palaeocreation 2013 sculpture

High areas, such as the Mendip Hills, a ridge across the Clifton Downs in Bristol, and the hills of South Wales poked through the water, forming an archipelago of 20 to 30 islands. The islands were made from limestone which became fissured and cracked with rainfall, forming cave systems.

“The process was more complicated than simply drawing the ancient coastlines around the present-day 100-metre contour line because as sea levels rose, there was all kinds of small-scale faulting. The coastlines dropped in many places as sea levels rose,” said Jack, who is studying Palaeontology and Evolution.

The findings have provided greater insight into the type of surroundings inhabited by the Thecodontosaurus, a small dinosaur the size of a medium-sized dog with a long tail also known as the Bristol dinosaur.

Co-author Professor Michael Benton, Professor of Vertebrate Palaeontology at the University of Bristol, said: “I was keen we did this work to try to resolve just what the ancient landscape looked like in the Late Triassic. The Thecodontosaurus lived on several of these islands including the one that cut across the Clifton Downs, and we wanted to understand the world it occupied and why the dinosaurs on different islands show some differences. Perhaps they couldn’t swim too well.”

“We also wanted to see whether these early island-dwellers showed any of the effects of island life,” said co-author Dr David Whiteside, Research Associate at the University of Bristol.

The Bristol dinosaur. Thecodontos aurus, standing on one of the palaeo-island’s beaches. Artwork by Fabio Pastori, pixel-shack.com; © University of Bristol

“On islands today, middle-sized animals are often dwarfed because there are fewer resources, and we found that in the case of the Bristol archipelago. Also, we found evidence that the small islands were occupied by small numbers of species, whereas larger islands, such as the Mendip Island, could support many more.”

The study, carried out with the British Geological Survey, demonstrates the level of detail that can be drawn from geological information using modern analytical tools. The new map even shows how the Mendip Island was flooded step-by-step, with sea level rising a few metres every million years, until it became nearly completely flooded 100 million years later, in the Cretaceous.

Co-author Dr Andy Newell, of the British Geological Survey, said: “It was great working on this project because 3D models of the Earth’s crust can help us understand so much about the history of the landscape, and also where to find water resources. In the UK we have this rich resource of historical data from mining and other development, and we now have the computational tools to make complex, but accurate, models.”

Featured image: 3D model used to generate maps of the palaeo-island chain. Showing the palaeozoic strata surface in green relative to the Triassic strata surface in blue. Short version: 3D model used to generate maps of the palaeo-island chain © Lovegrove et al.

Paper: ‘Testing the relationship between marine transgression and evolving island palaeogeography using 3D GIS: an example from the Late Triassic of SW England’ by Lovegrove, J., Newell, A.J., Whiteside, D.I., and Benton, M.J in Journal of the Geological Society, 2021. https://jgs.lyellcollection.org/content/early/2021/02/24/jgs2020-158

Provided by University of Bristol

Asteroid Dust Found in Crater Closes Case of Dinosaur Extinction (Geology / Paleontology)

Researchers believe they have closed the case of what killed the dinosaurs, definitively linking their extinction with an asteroid that slammed into Earth 66 million years ago by finding a key piece of evidence: asteroid dust inside the impact crater.

Death by asteroid rather than by a series of volcanic eruptions or some other global calamity has been the leading hypothesis since the 1980s, when scientists found asteroid dust in the geologic layer that marks the extinction of the dinosaurs. This discovery painted an apocalyptic picture of dust from the vaporized asteroid and rocks from impact circling the planet, blocking out the sun and bringing about mass death through a dark, sustained global winter – all before drifting back to Earth to form the layer enriched in asteroid material that’s visible today.

In the 1990s, the connection was strengthened with the discovery of a 125-mile-wide Chicxulub impact crater beneath the Gulf of Mexico that is the same age as the rock layer. The new study seals the deal, researchers said, by finding asteroid dust with a matching chemical fingerprint within that crater at the precise geological location that marks the time of the extinction.

The crater left by the asteroid that wiped out the dinosaurs is located in the Yucatán Peninsula. It is called Chicxulub after a nearby town. Part of the crater is offshore and part of it is on land. The crater is buried beneath many layers of rock and sediment. A 2016 mission led by the International Ocean Discovery Program extracted rock cores from the offshore portion of the crater. Credit: The University of Texas at Austin/Jackson School of Geosciences/ Google Map.

“The circle is now finally complete,” said Steven Goderis, a geochemistry professor at the Vrije Universiteit Brussel, who led the study published in Science Advances on Feb. 24.

The study is the latest to come from a 2016 International Ocean Discovery Program mission co-led by The University of Texas at Austin that collected nearly 3,000 feet of rock core from the crater buried under the seafloor. Research from this mission has helped fill in gaps about the impactthe aftermath and the recovery of life.

The telltale sign of asteroid dust is the element iridium – which is rare in the Earth’s crust, but present at elevated levels in certain types of asteroids. An iridium spike in the geologic layer found all over the world is how the asteroid hypothesis was born. In the new study, researchers found a similar spike in a section of rock pulled from the crater. In the crater, the sediment layer deposited in the days to years after the strike is so thick that scientists were able to precisely date the dust to a mere two decades after impact.

“We are now at the level of coincidence that geologically doesn’t happen without causation,” said co-author Sean Gulick, a research professor at the UT Jackson School of Geosciences who co-led the 2016 expedition with Joanna Morgan of Imperial College London. “It puts to bed any doubts that the iridium anomaly [in the geologic layer] is not related to the Chicxulub crater.”

Sean Gulick, a research professor at The University of Texas at Austin Jackson School of Geosciences (right), and Joanna Morgan, a professor at Imperial College London, examine rock cores retrieved from the crater during the 2016 research mission led by the International Ocean Discovery Program. Credit: The University of Texas at Austin/ Jackson School of Geosciences.

The dust is all that remains of the 7-mile-wide asteroid that slammed into the planet millions of years ago, triggering the extinction of 75% of life on Earth, including all nonavian dinosaurs.

Researchers estimate that the dust kicked up by the impact circulated in the atmosphere for no more than a couple of decades – which, Gulick points out, helps time how long extinction took.

“If you’re actually going to put a clock on extinction 66 million years ago, you could easily make an argument that it all happened within a couple of decades, which is basically how long it takes for everything to starve to death,” he said.

A section of rock core pulled from the crater left by the asteroid impact that wiped out the dinosaurs. Researchers found high concentrations of the element iridium –a marker for asteroid material –in the middle section of the core, which contains a mixture of ash from the impact and ocean sediment deposited over decades. The iridium is measured in parts per billion. Credit: International Ocean Discovery Program.

The highest concentrations of iridium were found within a 5-centimeter section of the rock core retrieved from the top of the crater’s peak ring – a high-elevation point in the crater that formed when rocks rebounded then collapsed from the force of impact.

The iridium analysis was carried out by labs in Austria, Belgium, Japan and the United States.

“We combined the results from four independent laboratories around the world to make sure we got this right,” said Goderis.

In addition to iridium, the crater section showed elevated levels of other elements associated with asteroid material. The concentration and composition of these “asteroid elements” resembled measurements taken from the geologic layer at 52 sites around the world.

The core section and geologic layer also have earthbound elements in common, including sulfurous compounds. A 2019 study found that sulfur-bearing rocks are missing from much of the rest of the core despite being present in large volumes in the surrounding limestone. This indicates that the impact blew the original sulfur into the atmosphere, where it may have made a bad situation worse by exacerbating global cooling and seeding acid rain.

Gulick and colleagues at the University of Texas Institute for Geophysics and Bureau of Economic Geology – both units of the UT Jackson School – plan to return to the crater this summer to begin surveying sites at its center, where they hope to plan a future drilling effort to recover more asteroid material.

Featured image: The asteroid impact led to the extinction of 75% of life, including all non-avian dinosaurs. Credit: Willgard Krause/Pixabay.

Reference: Steven Goderis, Honami Sato, Ludovic Ferrière, Birger Schmitz, David Burney, Pim Kaskes, Johan Vellekoop, Axel Wittmann, Toni Schulz, Stepan M. Chernonozhkin, Philippe Claeys, Sietze J. de Graaff, Thomas Déhais, Niels J. de Winter, Mikael Elfman, Jean-Guillaume Feignon, Akira Ishikawa, Christian Koeberl, Per Kristiansson, Clive R. Neal, Jeremy D. Owens, Martin Schmieder, Matthias Sinnesael, Frank Vanhaecke, Stijn J. M. Van Malderen, Timothy J. Bralower, Sean P. S. Gulick, David A. Kring, Christopher M. Lowery, Joanna V. Morgan, Jan Smit, Michael T. Whalen, IODP-ICDP Expedition 364 Scientists, “Globally distributed iridium layer preserved within the Chicxulub impact structure”, Science Advances 24 Feb 2021: Vol. 7, no. 9, eabe3647 DOI: 10.1126/sciadv.abe3647

Provided by University of Texas