Tag Archives: #dinosaurs

Bird Brains Left Other Dinosaurs Behind (Paleontology)

Today, being “birdbrained” means forgetting where you left your keys or wallet. But 66 million years ago, it may have meant the difference between life and death – and may help explain why birds are the only dinosaurs left on Earth.

Research on a newly discovered bird fossil led by The University of Texas at Austin found that a unique brain shape may be why the ancestors of living birds survived the mass extinction that claimed all other known dinosaurs.

A fossil skull of Ichthyornis, a bird that lived 70 million years ago during the late Cretaceous Period.
A fossil skull of Ichthyornis, a bird that lived 70 million years ago during the late Cretaceous Period. Credit: Christopher Torres / The University of Texas at Austin

“Living birds have brains more complex than any known animals except mammals,” said lead investigator Christopher Torres, who conducted the research while earning a Ph.D. from the UT College of Natural Sciences and is now a National Science Foundation postdoctoral fellow at Ohio University and research associate at the UT Jackson School of Geosciences. “This new fossil finally lets us test the idea that those brains played a major role in their survival.”

The fossil is about 70 million years old and has a nearly complete skull, a rare occurrence in the fossil record that allowed the scientists to compare the ancient bird to birds living today.

The findings were published July 30 in the journal Science Advances.

The fossil is a new specimen of a bird named Ichthyornis, which went extinct at the same time as other nonavian dinosaurs and lived in what is now Kansas during the late Cretaceous Period. Ichthyornis has a blend of avian and nonavian dinosaur-like characteristics – including jaws full of teeth but tipped with a beak. The intact skull let Torres and his collaborators get a closer look at the brain.

Bird skulls wrap tightly around their brains. With CT-imaging data, the researchers used the skull of Ichthyornis like a mold to create a 3D replica of its brain called an endocast. They compared that endocast with ones created for living birds and more distant dinosaurian relatives.

The researchers found that the brain of Ichthyornis had more in common with nonavian dinosaurs than living birds. In particular, the cerebral hemispheres – where higher cognitive functions such as speech, thought and emotion occur in humans – are much bigger in living birds than in Ichthyornis. That pattern suggests that these functions could be connected to surviving the mass extinction.

“If a feature of the brain affected survivorship, we would expect it to be present in the survivors but absent in the casualties, like Ichthyornis,” said Torres. “That’s exactly what we see here.”

The ancestors of living birds had a brain shape that was much different from other dinosaurs (including other early birds). This suggests that brain differences may have affected survival during the mass extinction that wiped out all nonavian dinosaurs. Credit: Christopher Torres / The University of Texas at Austin.

The search for skulls from early birds and closely related dinosaurs has been challenging paleontologists for centuries. Bird skeletons are notoriously brittle and rarely survive in the fossil record intact in three dimensions. Well-preserved skulls are particularly rare – but that’s exactly what scientists need in order to understand what their brains were like in life.

Ichthyornis is key to unraveling that mystery,” said Julia Clarke, a professor at the UT Jackson School of Geosciences and co-author of the study. “This fossil helps bring us much closer to answering some persistent questions concerning living birds and their survivorship among dinosaurs.”

Mark Norell, the curator and division chair of paleontology at the American Museum of Natural History, co-authored the study. This work was funded by the Howard Hughes Medical Institute Science Education Program, the Jackson School of Geosciences and the American Museum of Natural History.

Featured image: A transparent 3D model of the fossil bird skull and brain (in pink). Christopher Torres / The University of Texas at Austin.

Reference: Christopher R. Torres et al, Bird neurocranial and body mass evolution across the end-Cretaceous mass extinction: The avian brain shape left other dinosaurs behind, Science Advances (2021). DOI: 10.1126/sciadv.abg7099

Provided by University of Texas at Austin

SwRI Team Zeroes In On Source Of the Impactor That Wiped Out the Dinosaurs (Planetary Science)

The impactor believed to have wiped out the dinosaurs and other life forms on Earth some 66 million years ago likely came from the outer half of the main asteroid belt, a region previously thought to produce few impactors. Researchers from Southwest Research Institute have shown that the processes that deliver large asteroids to Earth from that region occur at least 10 times more frequently than previously thought and that the composition of these bodies match what we know of the dinosaur-killing impactor. 

The SwRI team — including Dr. David Nesvorný, Dr. William Bottke and Dr. Simone Marchi — combined computer models of asteroid evolution with observations of known asteroids to investigate the frequency of so-called Chicxulub events. Over 66 million years ago, a body estimated to be 6 miles across hit in what is now Mexico’s Yucatan peninsula and formed Chicxulub crater, which is over 90 miles across. This massive blast triggered a mass extinction event that ended the reign of the dinosaurs. Over the last several decades, much has been learned about the Chicxulub event, but every advance has led to new questions.

“Two critical ones still unanswered are: ‘What was the source of the impactor?’ and ‘How often did such impact events occur on Earth in the past?’” Bottke said.

To probe the Chicxulub impact, geologists have previously examined 66-million-year-old rock samples found on land and within drill cores. The results indicate the impactor was similar to the carbonaceous chondrite class of meteorites, some of the most pristine materials in the solar system. Curiously, while carbonaceous chondrites are common among the many mile-wide bodies that approach the Earth, none today are close to the sizes needed to produce the Chicxulub impact with any kind of reasonable probability.

“We decided to look for where the siblings of the Chicxulub impactor might be hiding,” said Nesvorný, lead author of a paper describing the research.

“To explain their absence, several past groups have simulated large asteroid and comet breakups in the inner solar system, looking at surges of impacts on Earth with the largest one producing Chicxulub crater,” said Bottke, one of the paper’s co-authors. “While many of these models had interesting properties, none provided a satisfying match to what we know about asteroids and comets. It seemed like we were still missing something important.” 

To solve this problem, the team used computer models that track how objects escape the main asteroid belt, a zone of small bodies located between the orbits of Mars and Jupiter. Over eons, thermal forces allow these objects to drift into dynamical “escape hatches” where the gravitational kicks of the planets can push them into orbits nearing Earth. Using NASA’s Pleaides Supercomputer, the team followed 130,000 model asteroids evolving in this slow, steady manner for hundreds of millions of years. Particular attention was given to asteroids located in the outer half of the asteroid belt, the part that is furthest from the Sun. To their surprise, they found that 6-mile-wide asteroids from this region strike the Earth at least 10 times more often than previously calculated.

“This result is intriguing not only because the outer half of the asteroid belt is home to large numbers of carbonaceous chondrite impactors, but also because the team’s simulations can, for the first time, reproduce the orbits of large asteroids on the verge of approaching Earth,” said co-author Marchi. “Our explanation for the source of the Chicxulub impactor fits in beautifully with what we already know about how asteroids evolve.”

Overall, the team found that 6-mile-wide asteroids hit the Earth once every 250 million years on average, a timescale that yields reasonable odds that the Chicxulub crater occurred 66 million years ago. Moreover, nearly half of impacts were from carbonaceous chondrites, a good match with what is known about the Chicxulub impactor.

“This work will help us better understand the nature of the Chicxulub impact, while also telling us where other large impactors from Earth’s deep past might have originated,” Nesvorný said.

The journal Icarus is publishing a paper about this research, “Dark Primitive Asteroids Account for a Large Share of K/Pg-Scale Impacts on the Earth” (Volume 368, 1 November 2021, 114621, Elsevier publications).

A link to the published paper can be found here: https://doi.org/10.1016/j.icarus.2021.114621 , while a preprint is available here: https://arxiv.org/abs/2107.03458.

Featured image: An SwRI team modeled evolutionary processes in the main asteroid belt and discovered that impactors such as the one that ended the reign of the dinosaurs are most likely from the outer half of the main asteroid belt. The team also discovered that delivery processes from that region occur 10 times more often than previously thought. © Courtesy of SwRI/Don Davis

Provided by Southwest Research Institute

Newly-hatched Pterosaurs May Have Been Able To Fly (Paleontology)

Newly-hatched pterosaurs may have been able to fly but their flying abilities may have been different from adult pterosaurs, according to a new study.

Pterosaurs were a group of flying reptiles that lived during the Triassic, Jurassic and Cretaceous Periods (228 to 66 million years ago). Due to the rarity of fossilized pterosaur eggs and embryos, and difficulties distinguishing between hatchlings and small adults, it has been unclear whether newly-hatched pterosaurs were able to fly.

Researchers from the Universities of Portsmouth and Bristol, along with paleontologist Darren Naish, found that hatchling humerus bones were stronger than those of many adult pterosaurs, indicating that they would have been strong enough for flight.

In the study, published in Scientific Reports, the researchers modeled the flying abilities of hatchlings using previously obtained wing measurements from four established hatchling and embryo fossils from two pterosaur species, Pterodaustro guinazui and Sinopterus dongi. They also compared these wing measurements with those of adults from the same species and compared the strength of the humerus bone, which forms part of the wing, of three hatchlings with those of 22 adult pterosaurs.

Study co-author Dr. Mark Witton from the University of Portsmouth said: “Although we’ve known about pterosaurs for over two centuries, we’ve only had fossils of their embryos and hatchlings since 2004. We’re still trying to understand the early stages of life in these animals. One discussion has centered around whether pterosaurs could fly as hatchlings or, like the vast majority of birds and bats, they had to grow a little before they could take wing.

“We found that these tiny animals—with 25 cm wingspans and bodies that could neatly fit in your hand—were very strong, capable fliers. Their bones were strong enough to sustain flapping and take-off, and their wings were ideally shaped for powered (as opposed to gliding) flight. However, they would not have flown exactly like their parents simply because they were so much smaller: flight capabilities are strongly influenced by size and mass, and so pterosaur hatchlings, being hundreds of times smaller than their parents, were likely slower, more agile fliers than the wide-ranging, but less maneuverable adults.”

The researchers found that while hatchlings had long, narrow wings suited to long-distance flight, their wings were shorter and broader than those of adult pterosaurs, with a larger wing area relative to hatchling mass and body size. These wing dimensions may have made hatchlings less efficient than adult pterosaurs at long-distance travel, but may have resulted in them being more agile fliers, enabling them to suddenly change direction and speed.

The authors speculate that the agile flying style of hatchling pterosaurs may have enabled them to rapidly escape predators and made them better suited to chasing nimbler prey and flying amongst dense vegetation than adult pterosaurs.

Dr. Witton said: “That gives us a lot to think about with regard to flying reptile ecology. How independent were the hatchlings from their parents? Did flight style influence habitat choices, and did these change as pterosaurs grew? There’s still a lot to learn about the life histories of these animals, but we’re confident that, whatever they were doing as they grew up, they were capable of flying from the moment they hatched.”

Featured image: A flock of adult and hatchling flamingo-like pterosaurs, Pterodaustro guinazui, take flight in Early Cretaceous Argentina. Credit: Mark Witton.

Reference: Naish, D., Witton, M.P. & Martin-Silverstone, E. Powered flight in hatchling pterosaurs: evidence from wing form and bone strength. Sci Rep 11, 13130 (2021). https://doi.org/10.1038/s41598-021-92499-z

Provided by University of Portsmouth

A Foot Tumour And Two Tail Fractures Complicated The Life of This Hadrosaur (Paleontology)

When it was discovered in the 1980s in Argentina, this hadrosaur was diagnosed with a fractured foot. However, a new analysis now shows that this ornithopod commonly known as the duck-billed dinosaur actually had a tumour some 70 million years ago, as well as two painful fractures in the vertebrae of its tail, despite which, it managed to survive for some time.

This dinosaur, called Bonapartesaurus rionegrensis, was discovered in Argentinean Patagonia in the 1980s, and the first analyses of its fossils indicated an ailment of the foot, possibly a fracture, as the Argentinean palaeontologist Jaime Powell pointed out at the time. The study of this animal then came to a standstill until 2016, when Powell invited another team of scientists to resume the research.

The presence of diseases such as tumours confirms that they already existed at a very early age and among a very diverse group of animals

“In addition to the ailment of the foot, there were other possible fractures in several neural spines of the vertebrae of the tail,” as Penélope Cruzado-Caballero, the lead author of the study, now published in the journal Cretaceous Research, and a scientist at the Research Institute of Palaeobiology and Geology of CONICET and the National University of Río Negro (Argentina), as well as a professor at the University of La Laguna (Tenerife, Spain), has told SINC. 

The researchers decided to analyse them all to see this hadrosaur, also known as duck-billed dinosaur, “during its lifetime” and to see how it was able to interact with the environment, with its fellows, and with predators while suffering from these problems. 

Scientists were particularly surprised by the condition of the foot. “We were struck by the large overgrowth of bone that gave it a cauliflower-like appearance and covered almost the entire metatarsal,” the researcher points out. When studying the histology and CT scans of the fossil, the team did not find a fracture. Instead, the indicators showed a reduction in bone density and several areas where cortical tissue had been destroyed. 

“We were probably looking at a cancer or a neoplasm, such as an osteosarcoma,” specifies Cruzado-Caballero. The presence of diseases such as tumours confirms that they already existed at a very early age and among a very diverse group of animals.

“Despite the large development of the cancer, it did not significantly affect the muscle insertion zone, so we cannot be sure that the lesion affected its locomotion,” says the palaeontologist. The study has allowed us to determine that the tumour did not spread to other bones – since this ornithopod preserved almost half of its skeleton -, “so, although it severely affected the metatarsus, it did not cause its death,” she adds.

Tail fractures followed by infections

In addition to the foot tumour, other pathologies were identified in the neural spines of two vertebrae in Bonapartesaurus rionegrensis’s tail. According to the scientists, one of the vertebrae had a displaced fracture that had almost healed. “It was probably related to an injury resulting from a strong blow that caused the bone to be displaced and to heal in this manner, giving the spine a curved appearance,” Cruzado-Caballero stresses.

In addition to the foot tumour, other pathologies were identified in the neural spines of two vertebrae in Bonapartesaurus rionegrensis’s tail.

The other vertebra had an almost completely healed fracture also produced by a stress event (it is not known if it was due to impact), which did not lead to the displacement of the bone. Although the spine maintains its straight shape, the researchers observed a swelling that formed a callus on the bone as it healed. 

“These fractures, especially in the case of the displaced fracture, must have been associated with infections following the rupture of the muscles surrounding the bone,” says the researcher, who considers that they must have been painful not only because of the blow, but also because of the infections that could have impeded the mobility of the tail and caused this specimen a great deal of discomfort when it moved. 

However, despite the severity of the ailments, the death of Bonapartesaurus rionegrensis did not follow immediately after its injuries, the authors point out. “But we cannot quantify how long it lived afterwards, which means that it could have lived for months or years. Nor can we confirm that these injuries were the final cause of its death,” comments the scientist. 

This hadrosaur, although badly injured, therefore managed to survive and continued to interact with its fellows, despite the initial pain caused by fractures and infections. These could have been caused by falling, hitting an object or another animal to defend itself from predators, or even by being trampled on the tail by another hadrosaur. 

Featured image: Despite the seriousness of its foot and tail vertebrae ailments, Bonapartesaurus rionegrensis did not die immediately after its injuries / José Antonio Peñas (SINC)


Penélope Cruzado-Caballero et al. “Osseous paleopathologies of Bonapartesaurus rionegrensis (Ornithopoda, Hadrosauridae) from Allen Formation (Upper Cretaceous) of Patagonia Argentina” Cretaceous Research

Provided by SINC

Sharp Size Reduction In Dinosaurs That Changed Diet to Termites (Paleontology)

Dinosaurs were generally huge, but a new study of the unusual alvarezsaurs show that they reduced in size about 100 million years ago when they became specialised ant-eaters.

The new work is led by Zichuan Qin, a PhD student at the University of Bristol and Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. He measured body sizes of dozens of specimens and showed that they ranged in size from 10-70 kg, the size of a large turkey to a small ostrich, for most of their existence and then plummeted rapidly to chicken-sized animals at the same time as they adopted a remarkable new diet: ant-eating.

The alvarezsaurs lived from the Late Jurassic to Late Cretaceous (160 to 70 million years ago) in many parts of the world, including China, Mongolia, and South America. They were slender, two-legged predators for most of their time on Earth, pursuing lizards, early mammals, and baby dinosaurs as their diet.

“Perhaps competition with other dinosaurs intensified through the Cretaceous,” says Prof Michael Benton, one of Zichuan’s supervisors, at Bristol’s School of Earth Sciences. “The Cretaceous was a time of rapidly evolving ecosystems and the biggest change was the gradual takeover by flowering plants. Flowering plants changed the nature of the landscape completely, and yet dinosaurs mostly did not feed on these new plants. But they led to an explosion of new types of insects, including ants and termites.”

Graphic: Bone tissue (osteohistological) sampling, body mass evolution and explosive diversification of Alvarezsauroidea. © Zichuan Qin

This restructuring of ecosystems has been called the Cretaceous Terrestrial Revolution, marking the time when modern-style forests and woodlands emerged, with diverse plants and animals, including insects that specialised to pollinate the new flowers and to feed on their leaves, petals and nectar.

A key problem with many alvarezsaur specimens, especially the chicken-sized ones, was to be sure they were all adults. “Some of the skeletons clearly came from juveniles,” says Dr Qi Zhao, a co-author and an expert on bone histology, “and we could tell this from sections through the bone. These showed the ages of the dinosaurs when they died, depending on the number of growth rings in the bone. We were able to identify that some specimens came from babies and juveniles and so we left them out of the calculations.”

Ant-eating might seem an amazing diet for dinosaurs. “This was suggested years ago when the arms of Mononykus were reported from Mongolia,” says Professor James Clark in Washington, DC, a co-author of this paper, and also one of the first discoverers of tiny alvarezsaurs from Mongolia. “Mononykus was one of the small alvarezsaurs, just about 1 metre long, but probably weighing 4-5 kilograms, a decent-sized Christmas turkey. Its arm was short and stout and it had lost all but one of its fingers which was modified as a short spike. It looked like a punchy little arm, no good for grabbing things, but ideal for punching a hole in the side of a termite mound.”

“Interestingly, alvarezsaur dinosaurs were indeed not small in size or ant eaters at start,” says Professor Jonah Choiniere in South Africa, a co-author of this paper, who was first to report the earliest alvarezsaurs in China. “Their ancestors, like Haplocheirus, are relatively large, close to the size of a small ostrich, and their sharp teeth, flexible forelimbs and big eyes suggest they had a mixed diet.”

Zichuan Qin took all the measurements of body size and mapped these across a dated evolutionary tree of the alvarezsaurs. “My calculations show how body sizes went up and down for the first 90 million years they existed, ranging from turkey to ostrich-sized, and averaging 30-40 kg,” says Zichuan. “Then, 95 million years ago, their body size suddenly dropped to 5 kg, and their claw shapes changed from grabbing and cutting to punching.”

“This is a very strange result, but it seems to be true,” says Professor Xing Xu, a co-supervisor to Zichuan in Beijing. “All other dinosaurs were getting bigger and bigger, but one group of flesh-eaters miniaturized, and this was associated with living in trees and flying. They eventually became birds. We’ve identified a second miniaturization event – but it wasn’t for flight, but to accommodate a completely new diet, switching from flesh to termites.”

Featured image: Painting: Artistic reconstruction of four representative alvarezsauroids, Haplocheirus sollers (left), Patagonykus puertai (upper middle), Linhenykus monodactylus (lower middle) and Bannykus wulatensis (lower right), illustrating the body size and dieting change in alvarezsauroid dinosaurs © Zhixin Han/ https://www.artstation.com/xinyanjun

The paper

‘Growth and miniaturization among alvarezsauroid dinosaurs’ by Zichuan Qin, Qi Zhao, Jonah N. Choiniere, James M. Clark, Michael J. Benton and Xing Xu. Current Biology

Provided by University of Bristol

New Fossil Sheds Light On The Evolution of How Dinosaurs Breathed (Paleontology)

An international team of scientists has used high-powered X-rays at the European Synchrotron to show how an extinct South African 200-million-year-old dinosaur, Heterodontosaurus tucki, breathed. The study, published in eLife, demonstrates that not all dinosaurs breathed in the same way.

In 2016, scientists from the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa, came to the ESRF, the European Synchrotron in Grenoble, France, the brightest synchrotron light source, for an exceptional study: to scan the complete skeleton of a small, 200-million-year-old plant-eating dinosaur. The dinosaur specimen is the most complete fossil ever discovered of a species known as Heterodontosaurus tucki. The fossil was found in 2009 in the Eastern Cape of South Africa by study co-author, Billy de Klerk of the Albany Museum, Makhanda, South Africa. “A farmer friend of mine called my attention to the specimen”, says de Klerk, “and when I saw it I immediately knew we had something special on our hands.”

Fast forward some years: the team of scientists use scans and new algorithms developed by ESRF scientists to virtually reconstruct the skeleton of Heterodontosaurus in unprecedented detail, and thus show how this extinct dinosaur breathed. “This specimen represents a turning point in understanding how dinosaurs evolved” explains Viktor Radermacher, corresponding author, a South African PhD student and now at the University of Minnesota, US.

The skull of the Heterodontosaurus tucki dinosaur. Credit: ESRF

Not all animals use the same techniques and organs to breathe. Humans expand and contract their lungs. Birds have air sacs outside their lungs that pump oxygen in, and their lungs don’t actually move. For a long time, paleontologists assumed that all dinosaurs breathed like birds, since they had similar breathing anatomy. This study, however, has found that Heterodontosaurus did not—it instead had paddle-shaped ribs and small, toothpick-like bones, and expanded both its chest and belly in order to breathe.

Heterodontosaurus is one of the oldest and first-evolving Ornithischians, the group that includes favourites like Triceratops, Stegosaurus, and duckbilled dinosaurs. Heterodontosaurus lived in the early Jurassic period, about 200 million years ago, surviving an extinction at the end of the prior Triassic period. Understanding how this dinosaur breathed could also help paleontologists figure out what biological features allowed certain dinosaurs to survive or caused them to go extinct.

Technical figure from study showing the step-wise increase of unique breathing muscle attached to pelvis. APP: Anterior pubic process; PPM: puboperitoneal muscle.
Jonah Chonière and Vincent Fernandez (right) setting the sample in the experimental hutch. © ESRF

“We’ve long known that the skeletons of ornithischian dinosaurs were radically different from those of other dinosaurs,” explains Richard Butler, from the School of Geography, Earth, and Environmental Sciences, University of Birmingham, UK. “This amazing new fossil helps us understand why ornithischians were so distinctive and successful”, he adds.

This study is the result of a long-standing collaboration between palaeontologists based in South Africa and at the ESRF, where non-invasive techniques have been developed specifically for palaeontological studies. “You could only do this study with a synchrotron” says Vincent Fernandez, scientist at the Natural History Museum in London, UK, co-author of the study and former ESRF scientist. “The characteristics of the ESRF’s X-rays, combined with its high energy beamline configuration, made scanning this complete turkey-sized dinosaur possible”.

This is a perfect example of the diversity of life on Earth. “The takeaway message is that there are many ways to breathe,” Radermacher said. “And the really interesting thing about life on earth is that we all have different strategies to do the same thing, and we’ve just identified a new strategy of breathing.”

“Studies like this highlight how South Africa’s fossil record once again helps us understand evolutionary origins” said senior author Jonah Choiniere, Professor at the Evolutionary Studies Institute, University of the Witwatersrand, South Africa.


Radermacher, V. J. et al, eLife, 06 July 2021, https://doi.org/10.7554/eLife.66036


Authors Viktor Radermacher, Kimberley Chapelle, and Jonah Choiniere were supported by grants from the NRF-African Origins Platform, Centre of Excellence in Palaeosciences, and the Palaeontological Scientific Trust. South African participation in the ESRF, the European synchrotron, is supported by the NRF and DSI.

Top image: The new Heterodontosaurus tucki specimen AM 4766 affectionately called “Tucky”. Life reconstruction on the right.

Provided by ESRF

Digging Into the Molecules of Fossilized Dinosaur Eggshells (Paleontology)

Dinosaurs roamed the Earth more than 65 million years ago, and paleontologists and amateur fossil hunters are still unearthing traces of them today. The minerals in fossilized eggs and shell fragments provide snapshots into these creatures’ early lives, as well as their fossilization processes. Now, researchers reporting in ACS Earth and Space Chemistry have analyzed the molecular makeup of fossilized dinosaur eggshells from Mexico, finding nine amino acids and evidence of ancient protein structures.

Current research indicates that all dinosaurs laid eggs, though most haven’t survived the test of time. And because whole eggs and shell fragments are very rare fossils, their mineral composition has not been widely investigated. Previously, Abel Moreno and colleagues reported the micro-architectures of eggshells from several species of dinosaurs found in Baja California. Although other teams have shown that some dinosaur eggshells contained calcium carbonate, carbohydrates and other compounds, no one has done similar analyses on the shells of species that Moreno’s team had collected. So, as a next step, these researchers wanted to look at the mineral and organic carbon-based components in fossilized eggshells from species that hatched in the Late Cretaceous.

The researchers collected five fossilized eggshells from dinosaurs in the Theropod (bipedal carnivores) and Hadrosauridae (duck-billed dinosaurs) families and an unidentified ootaxon. They found that calcium carbonate was the primary mineral, with smaller amounts of albite and quartz crystals. Anhydrite, hydroxyapatite and iron oxide impurities were also present in the shells, which the researchers suggest replaced some of the original minerals during fossilization. Then, with Fourier transform infrared spectroscopy (FT-IR), the team found nine amino acids among the five samples, but only lysine was in all of them. In addition, they identified evidence of secondary protein structures, including turns, α-helices, β-sheets and disordered structures, which were preserved for millions of years by being engrained in the minerals. The FT-IR bands corresponding to amino acids and secondary structures could be indicative of ancestral proteins that have not been characterized before, the researchers say. 

The authors acknowledge funding from NATO Science for Peace and Security Programme and National Council of Science and Technology (CONACYT) of Mexico.

“Molecular Analysis of the Mineral Phase and Examination of Possible Intramineral Proteins of Dinosaur Eggshells Collected in El Rosario, Baja California, Mexico”
ACS Earth and Space Chemistry

Featured image: An analysis of fossilized dinosaur eggshells (similar to the ones shown above) reveals nine amino acids and evidence of ancient protein structures.Credit: gorosan/Shutterstock.com

Provided by ACS

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