Tag Archives: dinosaur

Fossil Friday: new armless dinosaur species unearthed in Argentina

Researchers in Argentina have discovered a new — and pretty armless — species of dinosaur.

Carnotaurus sastrei, an abelisaurid relative of the new species, and probable look-alike dinosaur. Image credits Fred Wierum / Wikimedia.

Christened Guemesia ochoai, it was a species of abelisaurid, a clade of dinosaurs that roamed today’s Africa, South America, and India, and lived around 70 million years ago. Based on its age, researchers believe that this species was a close relative of the ancestors of all abelisaurids.

The animal’s partially-complete fossil skull was unearthed in Argentina and points to a unique ecosystem that developed in the area during the Late Cretaceous. The discovery is quite exciting as the area where it was found has yielded very few abelisaurid fossils, so it fills in an important piece of its historical puzzle.

Armless in Argentina

“This new dinosaur is quite unusual for its kind. It has several key characteristics that suggest that is a new species, providing important new information about an area of the world which we don’t know a lot about,” says Professor Anjali Goswami, co-author of the study describing the species and a Research Leader at the Natural History Museum of London.

“It shows that the dinosaurs that live in this region were quite different from those in other parts of Argentina, supporting the idea of distinct provinces in the Cretaceous of South America. It also shows us that there is lot more to be discovered in these areas that get less attention than some of the more famous fossil sites.”

By the time this species emerged, the ancient supercontinent of Pangaea had already begun to break apart forming Gondwana and Laurasia. The former would, in turn, split into the major continents in the Southern Hemisphere today and India.

Despite these landmasses slowly drifting apart, species could still move between them, so researchers assume that the fauna of these landmasses remained quite similar, as animals migrated between them. Abelisaurids were among these species.

Abelisaurids were top predators in their ecosystems, preying even on the mighty Titanosaurus. One of their most defining features was the front limbs; even shorter than those of the T. rex, these were virtually useless. In other words, the species did their hunting without being able to grasp, relying instead on their powerful jaws and necks to capture and subdue prey. They seem to have been quite successful at it, too: fossils of these dinosaurs have been found in rocks across Africa, South America, India, and Europe, dated all the way to the extinction of the dinosaurs 66 million years ago.

Although Argentina is well-known for abelisaur fossils (35 species have been discovered here so far), the overwhelming majority of these were discovered in Patagonia, in the country’s south. The north-western stretches of the country have yielded precious few. The newly-discovered skull joins this exclusive list.

The fossil, consisting of the braincase with the upper and back parts of the skull, was unearthed in the Los Blanquitos Formation near Amblayo, in the north of Argentina. The rocks it was encased in have been dated to between 75 and 65 million years ago. In other words, this specimen lived very close to the end-Cretaceous mass extinction, the event that wiped out the dinosaurs.

Like other abelisaurids, the skull contains a “remarkably small” braincase, according to its discoverers; its cranium is around 70% smaller than that of any of its relatives. This could suggest that the animal was a juvenile, but this is yet unconfirmed. One distinguishing feature of the dinosaur is a series of small holes at the front of its skull, arranged in rows, known as foramina. Researchers believe these holes helped the animal cool down, by allowing blood pumped into them (and covered by the thin skin at the front of the head) to release the heat it contained.

In contrast to other species of abelisaurids, the skull completely lacks any horns. This suggests that the species is among the first to emerge in the abelisaurid clade before these dinosaurs evolved horns.

Given that there is enough evidence to distinguish it as a new species, the team christened it after General Martin Miguel de Güemes, a hero of the Argentine War of Independence, and Javier Ochoa, a museum technician who discovered the specimen.

“Understanding huge global events like a mass extinction requires global datasets, but there are lots of parts of the world that have not been studied in detail, and tons of fossils remaining to be discovered,” Professor Anjali says.

“We left some exciting fossils in the ground on our last trip, not knowing that it would be years before we could get back to our field sites. Now we are hoping that it won’t be too much longer before we can finish digging them up and discovering many more species from this unique fauna.”

The paper “First definitive abelisaurid theropod from the Late Cretaceous of Northwestern Argentina” has been published in the Journal of Vertebrate Paleontology.

Researchers find a pristinely preserved dinosaur embryo in China

Discovering dinosaur embryos is very rare but also very important in order to understand their development. Some have been found in the past but most have been incomplete, with bones dislocated. That’s why the discovery of a perfectly preserved embryo inside a fossilized egg has raised excitement among scientists. 

Image credit: Author provided.

The embryo, named “Baby Yingliang,” was hidden in storage for 15 years in the Yingliang Sone Nature Museum – until the curator found it in 2015. He saw some bones on the broken section of an egg and arranged for fossil preparation, which revealed the embryo’s skeleton. The museum then invited a team of paleontologists to study it.

“We are very excited about the discovery – it is preserved in a great condition and helps us answer a lot of questions about dinosaur growth and reproduction with it,” Fiona Waisum, a researcher at the University of Birmingham and joint first author, said in a statement. “Dinosaur embryos are some of the rarest fossils and most of them are incomplete with the bones dislocated.”

A very well conserved embryo

The fossilized egg was first found in 2000 in Ganzhou, Jiangxi Province in southern China by a mining company. The workers suspected it was likely dinosaur fossils, so they notified the museum for study. The embryo is 27-centimeters long and lies in a very rare posture for dinosaur fossils – its feet are on each side of the head and its back is curled alongside the egg. 

If the posture sounds familiar, that’s because it’s similar to the hatching of a modern bird embryo. It’s a behavior known as “tucking,” which is critical for successful hatching. The position is supposed to help stabilize the head when a bird is breaking the eggshell with its beak. Failing to adopt it might lead to the death of the embryo. 

Image credit: The researchers.

Tucking is supposed to be unique to birds. But through comparisons of the posture of Baby Yingliang as well as other dinosaurs and birds, the team suggests that tucking could have evolved among theropod dinosaurs (bird’s ancestors) hundreds of million years ago. This adds up to other evidence of modern birds evolving from dinosaurs.

Based on its toothless and deep skull, the newly found embryo was identified by the researchers as an oviraptorosaur. These were a group of feathered theropod dinosaurs from the Cretaceous of Asia and North America related to modern birds. They had variable beak shapes and body sizes, allowing them to adopt different types of diets. 

“This dinosaur embryo inside its egg is one of the most beautiful fossils I have ever seen. This little prenatal dinosaur looks just like a baby bird curled in its egg, which is yet more evidence that many features characteristic of today’s birds first evolved in their dinosaur ancestors,” Steve Brusatte, part of the team, said in a statement.

The study, published in iScience, was conducted by researchers from the China University of Geosciences and the University of Birmingham. Looking ahead, the team hopes to do more comprehensive comparisons of Baby Yingliang with embryos of modern birds and crocodiles – the closest living relatives of dinosaurs – so as to better understand the early development of dinosaurs.

Dinosaur-killing asteroid may have hit Earth during spring

Credit: Pixabay.

About 66 million years ago, one of the worst disasters in history happened after a large asteroid struck Earth offshore Mexico’s Yucatan Peninsula. The cosmic impact unleashed the force of 10 billion Hiroshima A-bombs and released gigatons of sulfur and carbon dioxide, which could have lowered surface air temperatures by a staggering 26 degrees Celsius (47 degrees Fahrenheit). This global winter lasted for years, enough to devastate plant life and everything else along the food chain. Around 75% of all animals and plant species went extinct, including the iconic dinosaurs (except for birds).

To say this was bad luck would be a huge understatement. If the asteroid’s course was just a tiny fraction of a degree different, it would have missed Earth. Were the impact site in a different place, things could have been different too. The time of the year may have also made a difference in which species were wiped out or spared.

This latter point was partly the subject of a new study that found the asteroid impact likely took place in the spring or early summer in the Northern Hemisphere. The findings are based on controversial fossils from Tanis, a site in North Dakota where paleontologists found a huge trove of fish fossils. The freshwater creatures are believed to have all perished just hours after the asteroid impact.

Robert DePalma, a doctoral student at the University of Manchester in the UK, was in charge of analyzing the fossils, which still preserved growth lines in their skeletons. These growth lines can trace the life history of the fish, not all that different from how growth rings record a tree’s history of drought and rainfall. Like barcodes, they enable scientists to deduce unique details like whether or not the fish had plenty of food during a particular season of their lives.

During spring and summer, the bones of fish grow a darker layer while lighter bands form in fall and winter. Previously, DePalma and colleagues published a study in 2019 that found a massive surge of water fell upon Tanis as a result of a vast earthquake triggered by an asteroid impact, rapidly depositing sediments that locked in the fish remains. The last growth lines observed in the bones of the fish were light, suggesting the asteroid impact occurred in the spring or early summer.

This line of reasoning is supported by isotopic analysis of the growth lines, since the two types of growth lines have different ratios of carbon.

“This project has been a huge undertaking but well worth it. For so many years we’ve collected and processed the data, and now we have compelling evidence that changes how we think of the KPg event, but can simultaneously help us better prepare for future ecological and environmental hazards,” DePalma said in a statement.

“Extinction can mark the end of a dynasty, but we must not forget that our own species might not have evolved if it weren’t for the impact and the timing of events that saw the end of the dinosaurs”.

Robert DePalma (L) and Professor Phil Manning at the Iridium-bearing KPg boundary clay layer capping Tanis. Credit: University of Manchester.

In addition, the team of researchers also analyzed fossils of leaves that were damaged by insects, as well as fossilized adult mayflies found at the site, which also match the seasonal timing.

“They all matched up…everything points to the fact that the impact happened during the northern hemisphere equivalent of Spring to Summer months,” said co-author Loren Gurche.

Scientists looking to reconstruct the aftermath of the asteroid impact that caused the fifth mass extinction need every bit of evidence they can gather to paint a more accurate picture. Knowing which season of the year the asteroid struck may prove very important. Certain animals, for instance, are more vulnerable during certain times of the year, such as periods of growth and reproduction.

The data could also be applied today, helping scientists better understand how contemporary life responds to global-scale hazards.

The findings appeared in the journal Scientific Reports 

Fossil Friday: two new spinosaurids have been discovered in the UK

Researchers at the University of Southampton have described two new species of spinosaurid, a group of predatory dinosaurs, on the Isle of Wight.

Image credits Chris T. Barker et al., (2021), Nature.

The two dinosaurs belong to the theropod family and are close relatives of the distinctive Spinosaurus. Judging by the crocodile-like shape of their skull, these animals hunted prey on both land and water, the team explained. The species were described based on fossilized bones unearthed near Brighstone over several years. These included parts of two skulls and a large tail section. Overall, 50 different bones from the site have been unearthed from rocks in the 125-million-year-old Wessex Formation.

Apart from these two, only one other species of spinosaurid has previously been unearthed in the UK, the Baryonyx. Virtually all other findings consisted of isolated teeth or bones.


“We found the skulls to differ not only from Baryonyx, but also one another, suggesting the UK housed a greater diversity of spinosaurids than previously thought,” explains Chris Barker, a PhD student at the University of Southampton and lead author of the study.

“It might sound odd to have two similar and closely related carnivores in an ecosystem, but this is actually very common for both dinosaurs and numerous living ecosystems,” said Dr David Hone, co-author from Queen Mary University of London.

After analyzing the fossils at the University of Southampton, the authors determined that they didn’t belong to any previously identified species.

Following this, one specimen has been christened Ceratosuchops inferodios, roughly translating to “horned crocodile-faced hell heron”. This species is characterized by a series of short horns and bumps growing around the animal’s brow. The name was owed to its likely hunting style, which would be similar to that of a heron, which catches aquatic prey by lurking around the edges of waterways. At the same time, the diet of herons is much more flexible than most people would assume, and often includes terrestrial prey.

The other specimen was named Riparovenator milnerae, translating to “Milner’s riverbank hunter”. This name was given in honor of British paleontologist Angela Milner, who recently passed away. Dr. Milner was the one to study and name Baryonyx.

With the caveat that the skeletons are incomplete, so we can’t know for sure, the researchers estimate that both dinosaurs grew to around nine meters in length, and their skulls would grow to around a meter in length. Based on these fossils, the authors propose that spinosaurids likely evolved in Europe and then dispersed into Asia, Africa, and South America.

The rocks on the Isle of Wight where these fossils were found formed in an ancient floodplain environment in a Mediterranean climate. Remnants of forest fires can be seen as dark bands throughout the cliffs even up to today. However, at the time, this environment provided ample hunting opportunities consisting of fish, sharks, and crocodiles in various bodies of water.

“On behalf of the museum, I wish to express our gratitude to the collectors, including colleagues at the museum, who have made these amazing finds, and made them available for scientific research. We also congratulate the team who have worked on these exciting finds and brought them to publication” said Dr Martin Munt, Curator of Dinosaur Isle Museum.

The new fossils will go on display at Dinosaur Isle Museum at Sandown.

The paper “New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae” has been published in the journal Scientific Reports.

Adult T-Rexs likely couldn’t keep up with their offspring, judging from their paw prints

Could T. rex keep up with its kids? New research says ‘no’.

Image credits Brickset / Flickr.

Researchers at the University of New England’s (UNE) Paleoscience Research Centre found that young tyrannosaurs were much faster than their parents, suggesting that the adults could have had actual trouble keeping up with their young. It likely all came down to the significant difference in body size between adults and juveniles, the team explains.

The findings are based on a collection of fossilized tyrannosaur footprints which helped record how these animals moved throughout their different developmental stages.

Bigger, harder, stronger, slower

“Fully grown tyrannosaurs were believed to be more robust than younger individuals based on their relatively shorter hind limbs and more massive skulls, but nobody had explored this growth pattern using fossil footprints, which are unique in that they can provide a snapshot of the feet as they appeared in life, with outlines of the soft, fleshy parts of the foot that are rarely preserved as fossils,” said UNE PhD student and lead author of the paper, Nathan Enriquez.

“The results suggest that as some tyrannosaurs grew older and heavier, their feet also became comparably more bulky,” he adds, which would reduce their top speed.

There are a lot of elements that influence the final shape of a footprint. Things like soil composition and properties, the exact position of the animal as the print was made, the geography of the surface (and a lot of others) will influence the final shape that is imparted to a surface. Unsurprisingly, this makes interpreting footprints, especially fossilized ones, a very difficult process that’s fraught with pitfalls. Due to this, fossilized tracks haven’t been used extensively to understand dinosaur growth.

This set of footprints, however, from the Grande Prairie region of Northern Alberta, Canada, were found in very good condition and sported prints that belonged to individuals of the same species but different sizes.

“Based on the relatively close proximity between these discoveries and their nearly equivalent ages — about 72.5 million years old — we suggest they may indeed belong to the same species,” says Enriquez.

“We were also careful to assess the quality of preservation in each footprint, and only considered specimens which were likely to reflect the shape of the actual feet that produced them.”

After establishing which of the prints were suitable for their research, the team analyzed their outline using an approach called geometric morphometrics. This was meant to look past the differences in overall size between the tracks, and spot the key differences in shape between these tracks.

The most important difference in shape they found was the width and surface area of the heel relative to the overall imprint size. This ratio was significantly lower in the smaller prints. The team explains that the smaller tracks were “slender”, while the larger ones were “broader” and had larger heel areas. This increase was needed as the animal increased in size as it aged, as their legs needed to be able to physically support their bulk, but it also suggests that older individuals weren’t able to reach the same speeds as their young.

“Increasingly bulky feet in the adults aligns with previous suggestions that juvenile tyrannosaurs would have been faster and more agile for their body size in comparison to their parents, and means that we can add footprints as another line of evidence in the debate over tyrannosaur growth,” Enriquez notes.

One of the most exciting parts of science, for me personally, is that if you understand how the different parts of a picture fit together, you can then draw conclusions from seemingly unrelated elements — such as judging how fast an animal was able to go based on its pawprints.

Since we don’t have many reliable sources of data regarding long-extinct species such as T. rex, any sliver of information we can get is priceless. The current paper offers up one such tidbit which will help us better understand how the dinosaur’s abilities and ways of life changed as it aged. Hopefully, such an approach will be refined in the future to make it more reliable and widely-applicable, and that it will be used on prints from other dinosaur species as well.

The paper “Exploring possible ontogenetic trajectories in tyrannosaurids using tracks from the Wapiti Formation (upper Campanian) of Alberta, Canada” has been published in the Journal of Vertebrate Paleontology.

Researchers uncover the oldest known species with opposable thumbs — a dinosaur in China

Researchers have identified what is, perhaps, the oldest species to have evolved opposable thumbs; it was a dino.

 Reconstruction of Kunpengopterus antipollicatus. Image credits Chuang Zhao.

The new species, christened Kunpengopterus antipollicatus, lived during the Jurassic era in what is today China. Its most peculiar feature was the presence of opposable thumbs on its forelimbs, making it the oldest known species (and the oldest known dinosaur) to evolve such a trait. Opposable thumbs, the kind we have on our hands, are a big part of humanity’s secret to success, and a rare occurrence in nature outside of the primate family. As such, it earned the animal the nickname of “Monkeydactyl”.

Thumbs up

“The fingers of ‘Monkeydactyl’ are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through the rocks, create digital models and tell how the opposed thumb articulates with the other finger bones,” co-author Fion Waisum Ma said in a statement. “This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur — which wasn’t known for having an opposed thumb.”

If the fact that a dinosaur dared copy one of our trump cards isn’t enough, then know this: Kunpengopterus antipollicatus was also capable of flight, making it, objectively speaking, better than us. It used to live in the forest ecosystems of 160 million years ago, and its name antipollicatus means “opposite thumbed” in ancient Greek. 

K. antipollicatus belonged to the darwinopteran branch of the pterosaur family, the first lineage of vertebrates that we known of which were capable of flight. The current species is the oldest pterosaur to show true opposable thumbs, which also makes it the first species we know of that evolved such a trait.

Fossils of the new species were discovered in the Tiaojishan Formation of Liaoning, China, in September 2019. The opposable thumbs (or “pollex”) on each hand were spotted through the use of micro-CT scans. The team believes this dino used its thumbs for climbing trees or grasping, which would also be a useful skill for an animal living in the canopies of trees. Its diminutive size — the whole animal had a wingspan of 33 inches at most — also suggests it was adapted to spending some or most of its time in trees.

“Darwinopterans are a group of pterosaurs from the Jurassic of China and Europe, named after Darwin due to their unique transitional anatomy that has revealed how evolution affected the anatomy of pterosaurs throughout time,” said co-author Rodrigo V. Pêgas. “On top of that, a particular darwinopteran fossil has been preserved with two associated eggs, revealing clues to pterosaur reproduction.”

” They’ve always been considered precious fossils for these reasons and it is impressive that new darwinopteran species continue to surprise us!”

The species was most likely adapted to life in the trees in order to escape predators and competitors, the team conclude, a tradition that birds have carried on through to this day.

The paper “A new darwinopteran pterosaur reveals arborealism and an opposed thumb” has been published in the journal Current Biology.

Dino unearthed in Argentina is likely the oldest titanosaur we’ve ever seen

A titanic dinosaur discovered in Patagonia, Argentina, may be the oldest member of its lineage ever discovered.

Ninjatitan zapatai. Image credits Jorge González via Twitter/@emanuel_pujol.

The species, christened the quite cool name of Ninjatitan zapatai was a Titanosaurid, a lineage of massive plant-eating dinosaurs with long necks (they’re part of the sauropod family). All of them were quite hefty, with the smallest known titanosaurid being about as large as an elephant.

The oldest ninja titan

“During evolutionary history, sauropods had different moments, different ‘pulses’ of gigantism, which were not only related to the group of titanosaurs,” said Dr. Pablo Ariel Gallina, a paleontologist at the Fundación Azara in Maimonides University.

“There were large animals towards the end of the Jurassic period, such as Apatosaurus and Brachiosaurus. And, already in the line of titanosaurs, the pulse with the largest giants occurs towards the middle of the Cretaceous period with species such as Patagotitan, Argentinosaurus, or Notocolossus.”

N. zapatai was around 20 m (66 feet) in length, with a sizable neck and tail to go along. But its main distinguishing feature is its age — Ninjatitan zapatai lived during the Early Cretaceous, around 130 million years ago, making it the oldest known member of its lineage. Fossil records from that time are generally quite scant, not just for dinosaurs, making the discovery that much more valuable.

For starters, its existence gives us a lot of information about the wider ecology of the area during the Early Cretaceous. The specimen is proof that titanosaurian sauropods were already present and established in Patagonia at the time, likely even the wider southern hemisphere. It also supports the idea of a Gondwanan origin for Titanosauria,” the researchers said.

The 140-million-year-old postcranial remains of Ninjatitan zapatai were discovered in 2014 in the Bajada Colorada Formation in Neuquén province, Patagonia region, Argentina.

The paper “The earliest known titanosaur sauropod dinosaur” has been published in the journal Ameghiniana.

“Daddy, look at this”: 220-million-year-old dinosaur footprint discovered by four-year-old

Lily Wilder, aged 4, was walking with her father and per dog along a beach in south Wales, when she saw something unusual. It turned out to be a dinosaur footprint from the Triassic.

Image credits: National Museum Wales.

Although Lily doesn’t quite grasp exactly what she spotted yet, her keen eye is what found the footprint. She called to her dad who took photos and then posted them on a Facebook group, where he was directed to contact paleontologists. The incredibly well-preserved fossil is more than just a cool find: it can help researchers better understand how some dinosaurs walked around.

“It really is stunning preservation … You can see every detail of the muscles and where the joints are in the foot,” Cindy Howells, Amgueddfa Cymru National Museum of Wales paleontology curator, told NBC News. She called the footprint the “best specimen ever found” on the beach.

It’s not possible to tell exactly what species it was right now, but many things can be inferred about the dinosaur that left the footprint. It was probably about 75 cm tall, shorter than a horse but taller than a dog. The dinosaur would have walked on its two hind feet and hunted small animals, or maybe even insects.

“There are no fossilised bones from this 220 million-year-old dinosaur, but similar footprints in the USA are known to have been made by the dinosaur Coelophysis which does not occur in the UK,” reads a statement from the National Museum Cardiff, where the fossil will soon be hosted. “Many of the other footprints found at Bendricks Bay in the past have most likely not been from dinosaurs, but rather from some of the more crocodilian-type reptiles that also inhabited the area.” The museum also added that Lily will have her name listed as the one who discovered the footprint.

Dinosaurs first appeared some 230 million years ago, so this is one of the earliest ones to roam the Earth. It marks an important period, when dinosaurs were diversifying and exploring different ecological niches. They would have roamed across much of today’s Britain, but few fossils have ever been found in the area. As it enters the custody of the museum, it will be analyzed in greater detail by palaeontologists.

Meanwhile, Howell says that people should learn from this episode and try to spend more time in nature, especially in this very challenging pandemic period, when meeting with others can be so complicated. You never know what you may find, she says.

“Obviously, we don’t all have dinosaur footprints on our doorstep but there is a wealth of nature local to you if you take the time to really look close enough,” she says.

Tyrannosaurus rex started life as large as a Border Collie, a new paper reports

A new discovery shows that the king of the dinosaurs started life no larger than your average dog.

Artist’s impression of a juvenile tyrannosaur. Image credits Julius Csotonyi.

Tyrannosaurus rex (‘rex’ is Latin for ‘king’) is perhaps one of the best-known dinosaurs of all time. Movies such as Jurassic Park, and the dinosaur’s own impressive proportions (up to 40 feet / 12 meters in length as an adult) and body shape have cemented its image as a deadly, unstoppable predator in our minds.

While it definitely was very deadly, T. rex was likely very happy to act as a scavenger, not a hunter, when given the opportunity. And, while definitely much too large to pet in its adult years, this probably wasn’t true for its earliest days, as a new discovery shows.

Smallest big dinosaur

“These bones are the first window into the early lives of tyrannosaurs and they teach us about the size and appearance of baby tyrannosaurs,” explained University of Edinburgh paleontologist Greg Funston, lead author of the study.

“We now know they would have been the largest hatchlings to ever emerge from eggs, and they would have looked remarkably like their parents — both good signs for finding more material in the future. This may seem enormous, but remember that they would have been curled up inside an egg”.

The authors explain that the discovery of “the first-known fossils of tyrannosaur embryos” sheds light on how this immense dinosaur started his life. They aren’t T. rex exactly, but the embryos belonged to two closely-related species (Daspletosaurus and Albertosaurus sarcophagus), so they can give us some reliable information about the family as a whole. The fossils were unearthed in the U.S., Montana, and Canada, Alberta.

The team created 3D scans of the fossil fragments, allowing for a detailed analysis of their morphology. Armed with these scans, they determined (based on the size) that the bones belonged to juvenile, not-yet-hatched tyrannosaurs. Such fossils suggest that T. rex eggs (fossils of which we’ve not yet found) were around 17 inches (43 centimeters) long, and juveniles grew to around three feet long before hatching.

At this time, the dinosaur’s jaws would measure three centimeters in length (around 1.2 inches) but already had distinctive features such as a pronounced chin. This indicates that the main elements of a tyrannosaurs’ anatomy were already formed before hatching

Still, the paper also raises some questions. Why haven’t we found any T. rex eggs yet? The authors raise the possibility that the species laid soft-shelled eggs, which would be very unlikely to fossilize.

On the one hand, the findings can help make it easier to identify any tyrannosaur eggs we might discover in the future. On the other, it gives us a chance to look at adorable pictures of mini-dinosaurs, and that’s priceless.

The paper “Baby tyrannosaurid bones and teeth from the Late Cretaceous of western North America” has been published in the Canadian Journal of Earth Sciences.

The only preserved dinosaur butthole fossil is ‘one-of-a-kind’

Psittacosaurus may have used its ‘unique’ butthole for signaling during courtship, besides its primary obvious purpose. Credit: Bob Nicholls/Paleocreations.com 2020.

It’s amazing how much scientists have been able to learn about the secret lives of dinosaurs, creatures that went extinct more than 65 million years ago, just by studying their fossilized remains. Obviously, there are still a lot of loose ends owed to incomplete fossil records and due to the fact that many anatomical features rarely, if not never, fossilize. This is why scientists are excited about the first truly preserved dinosaur cloacal vent, the scientific name for the terminal end of the gastrointestinal tract in birds and amphibians, aka the butthole.

But this isn’t a butthole like any other. Speaking to Live Science, Jakob Vinther, a paleontologist at the University of Bristol in the United Kingdom, said that the dinosaur cloaca he studied isn’t like that of birds. It more closely resembles that of crocodiles, with two small bulges in proximity to the cloaca which might have had musky scent glands with a possible role in courtship. However, in many respects, the dinosaur cloaca was quite unique.

The oldest cloaca in the world was found sitting in a fossil display case in the Senckenberg Natural History Museum in Frankfurt, Germany, and belonged to a beaked, dog-sized dinosaur called Psittacosaurus.

A cloaca isn’t your typical butthole. It serves as an anus, in that it is the orifice through which waste ultimately exits the body after its journey through the intestinal tract. But the orifice, whose name comes from the Latin word for ‘sewer’, also plays a role in copulation and the extrusion of offspring or eggs.

The fossilized orifice was flattened over millions of years until it was unearthed from a basin in China decades ago. While working on a different study, Vinther was shocked to find that Psittacosaurus‘ posterior was intact after all these years and immediately enlisted colleagues to reconstruct it in 3-D. His team includes Robert Nicholls, a paleoartist, and Diane Kelly, a biologist at the University of Massachusetts Amherst who specializes in the evolution of genitalia.

The fossilized vent, top, and the authors’ reconstruction of it. Credit…J. Vinther, R. Nicholls and D. Kelly, Current Biology 2021

To reconstruct the dinosaur cloaca, the team had to study hundreds of preserved rear ends, from amphibians to chickens. Judging from these references and the fossils at their disposal, the researchers believe that Psittacosaurus‘ cloaca was flanked by a pair of dark-colored flaps of skin, which seems to be different from any living group known to science.

It’s exceedingly rare to find dinosaur soft tissue, so it’s no surprise that the cloaca’s interior couldn’t be analyzed. But if the dinosaur’s posterior was anything like that of crocodiles, its cloaca likely housed a penis or clitoris.

And fitting enough, the cloaca fossil was found next to a fossilized lump of feces, suggesting that the dinosaur was defecating when it suddenly succumbed and its fossils became locked in time. “It’s quite nice to find it, right near where it’s supposed to come out,” Vinther told The New York Times.

The findings were described in the journal Current Biology.

Fossil dino discovered in Argentina might have been the largest-ever animal on dry land

The remains of one dinosaur unearthed in Argentina, while yet unidentified, could have belonged to an immense creature.

Argentinosaurus huinculensis, a closely-related species of the new dinosaur. Image credits Nobu Tamura / Wikimedia.

Paleontologists have discovered the 98 million-year-old titanosaur in northwest Patagonia (the tip of the South American continent) in the Neuquén Province. The trove included 24 vertebrae from the tail, alongside elements of its pelvic and pectoral girdle, found in sedimentary deposits in the local Candeleros Formation. Titanosaurs, as their name suggests, were immense animals; believed to have been the largest animals to have ever walked on land.

Argentinian titan

“It is a huge dinosaur, but we expect to find much more of the skeleton in future field trips, so we’ll have the possibility to address with confidence how really big it was,” Alejandro Otero, a paleontologist with Argentina’s Museo de La Plata, told CNN.

Titanosaurs were part of the sauropod family, a group of dinosaurs known for their impressive size, long necks, and long tails. These four-legged animals were herbivores and were only contested by the most deadly top predators during their heyday — between the Late Jurassic and into the Cretaceous. So far, titanosaurs have been discovered on all continents except Antarctica.

The authors of the paper believe that the fossils could have belonged to “one of the largest sauropods ever found”, larger even than a Patagotitan, a species of dinosaur that grew up to 37.2 meters (122 feet) in length. Patagotitans have so far been found only in Patagonia (hence, the name) and they were really, really plump, growing to around 77 tons.

Without access to one of the newly-discovered dinosaur’s humerus or femur for a proper, in-depth analysis, it’s impossible to say for sure how much it weighed. Judging by the relative size of the bones they did find, however, it could very well be “considered one of the largest titanosaurs,” the team explains. It likely grew heavier than the Patagotitans or Argentionaurus (another local dino species that could grow up to 110 tons).

The authors say that the new discovery points to the co-existence of large and medium-sized titanosaurs alongside small-sized rebbachisaurids, a relatively obscure family of sauropods, in the area at the beginning of the Late Cretaceous period. Still, for now, they don’t believe we’re looking at a new species of dinosaur, but they haven’t been able to identify it either.

“These size differences could indeed explain the existence of such sauropod diversity in the Neuquén Basin during the Late Cretaceous in terms of niche partitioning,” they wrote.

The paper “Report of a giant titanosaur sauropod from the Upper Cretaceous of Neuquén Province, Argentina” has been published in the journal Cretaceous Research.

Strange dinosaur found in Brazil had stiff rods on its shoulders

Ubirajara jubatus was not your typical dinosaur. The newly described, chicken-sized creature had a mane of long fur down its back and a pair of stiff ribbons projecting back from each shoulder. These flamboyant features served to impress potential mates or intimidate adversaries, more than 110 million years before the first peacocks evolved.

The new species was discovered while researchers examined fossils in the collection of the State Museum of Natural History in Karlsruhe, Germany.

Immediately, the international team of researchers, including David Martill, a professor of palaeobiology at the University of Portsmouth, were stunned by the stiff ribbons projecting from the small dinosaur’s shoulders.

These ribbons weren’t bones, nor scales or fur. Instead, the long, flat ribbons were made of keratin, the same material that hair and feathers are made of. Strikingly, the researchers could tell all of this judging from x-ray scans of previously hidden skeletal elements encased in two slabs of stone from Brazil’s Crato Formation, a shallow inland sea laid down about 110 million years ago.

“Interpreting crushed bones is always challenging and it is very easy to get things wrong,” Martill told ZME Science.

But why go to all this trouble if these ribbons didn’t serve to immediately put food on the table, especially if it made you a walking target to predators? While it’s true that survivability drives the evolution of species through natural selection, evolution also favors reproduction, so individuals who were selected for their sexual fitness were naturally favored and could pass on their genes.

The peacock is famous in this regard and is often used as a prime example of sexual selection. With his long, colorful feathers trailing behind him, the male peacock signals to the world: ‘Behold! I spare no resources to adorn myself even if that means making many foes.’ For some reason, females find that very appealing.

We may imagine that Ubirajara jubatus used in many regards its long shoulder ribbons as a peacock’s tail.

“I suppose that if the adornments were on the tail it could be called a peacock, but these are on the shoulders, so maybe it should be the ‘Captain’,” Martill said jokingly.

Although it’s impossible to determine the sex of an individual with 100% accuracy, its size suggests that it was a young male. Perhaps the small dinosaur was still learning how to use its dazzling ribbons to woo potential mates when it died.

These ribbons were positioned in such a way as not to impede freedom of movement in the arms and legs. Its long, thick mane is believed to have been controlled by muscles, so it could have raised similar to the way a dog raises its hackles or a porcupine raises its spines when threatened. But when it didn’t require any display, the mane could be lowered close to the skin, allowing the dinosaur to move swiftly through dense vegetation.

Bizarre as it might have been, Ubirajara jubatus is an important contribution to the fossil record of feathered non-avian dinosaurs, which are very scarce in Latin America.

“Everybody loves dinosaurs and usually are thrilled when we can say something new or fascinating about them. And this little dinosaur has lots of new things about it. What’s next? Well, I have to wait to see what comes out of the ground on my next field trip,” Martill said.

The findings appeared in the journal Cretaceous Research.

Ireland’s first-ever dinosaur fossils confirmed

Researchers from the University of Portsmouth, Queen’s University Belfast, and National Museums Northern Ireland (NI) report on a first-ever for the island — the first-ever dinosaur bones to be discovered in Ireland.

Proximal fragment of left femur of Scelidosaurus. Image credits Michael Simms, et al., (2020), Proceedings of the Geologists’ Association.

The two fossils were discovered by Roger Byrne, a late fossil collector and schoolteacher, who donated them (among many other specimens he’s gathered) to Ulster Museum. Researchers were able to confirm that they hail from the early Jurassic, based on where they were discovered — rocks in Islandmagee, on the east coast of Northern Ireland.


“This is a hugely significant discovery. The great rarity of such fossils here is because most of Ireland’s rocks are the wrong age for dinosaurs, either too old or too young, making it nearly impossible to confirm dinosaurs existed on these shores,” explains Dr. Simms, National Museums NI, first author of the study. “The two dinosaur fossils that Roger Byrne found were perhaps swept out to sea, alive or dead, sinking to the Jurassic seabed where they were buried and fossilized.”

The only dinosaur bones ever found on the island of Ireland have been formally confirmed for the first time by a team of experts from the University of Portsmouth and Queen’s University Belfast, led by Dr. Mike Simms, a curator and paleontologist at National Museums NI.

Initially, the two fossils were believed to have belonged to the same animal. However, the authors report that they, in fact, belonged to two completely different dinos. One of them, a femur, belonged to a plant-eating species, Scelidosaurus. The other one was a tibia from a theropod, a two-legged predatory dinosaur similar to Sarcosaurus. The team identified their origin starting from high-resolution 3D models of the bone fragments.

. Proximal fragment of left tibia of megalosauroid theropod. Image credits Michael Simms, et al., (2020), Proceedings of the Geologists’ Association.

“Analyzing the shape and internal structure of the bones, we realized that they belonged to two very different animals. One is very dense and robust, typical of an armored plant-eater” says co-author Robert Smyth from the University of Portsmouth. “The other is slender, with thin bone walls and characteristics found only in fast-moving two-legged predatory dinosaurs called theropods”.

Although the specimens aren’t in ideal shape — they are, after all, broken into pieces, they still carry a huge paleontological weight. Not only were they discovered in Ireland, filling a gap in our understanding, but they also hail from an important time in the history of the dinosaurs. During the early Jurassic, about 200 million years ago, dinosaurs were poised to take the crown of the dominant terrestrial lineage and start dominating land ecosystems.

The paper “First dinosaur remains from Ireland” has been published in the journal Proceedings of the Geologists’ Association.

Scientists reconstruct the brain of one of the oldest dinosaurs in unprecedented detail

 Artist impression of the skull and brain of the sauropodomorph. Credit: Márcio L. Castro and Rodrigo Temp Müller.

Evolution can oftentimes be unpredictable. Around 230 million years ago, a dog-sized meat-eating dinosaur by the name of Buriolestes schultzi roamed Brazil’s forests. A hundred million years later, this small dinosaur’s cousins, such as Diplodocus and Brachiosaurus, grew to sizes spanning tens of meters in length and could weigh over 100 tons.

In many lineages, relative brain size tends to increase with time — but not in this case. According to paleontologists who performed one of the most accurate brain reconstructions of a dinosaur to date, Buriolestes schultzi‘s brain weighed approximately 1.5 grams or as much as a pea. Its humongous four-legged cousins’ brains, however, were no larger than a tennis ball, much smaller than you’d expect for their size.

The 3D reconstruction was based on three skulls unearthed by Dr. Rodrigo Temp Müller, a Brazilian paleontologist from the Universidade Federal de Santa Maria. Along with colleagues from the Universidade de São Paulo, the researchers employed computed tomography (CT) to draw inferences about the ancient dinosaur’s brain from the cavity left behind.

Buriolestes schultzi brain. Credit: Márcio L. Castro.

The small Jurassic carnivore was one of the earliest dinosaurs, and this shows in its primitively-shaped brain, which resembles the morphology of the crocodile brain.

However, Buriolestes had well-developed brain structures in the cerebellum, indicating superior abilities to track moving prey. It likely hunted using its eyes more than its nostrils, seeing how the olfactory bulb was relatively small, suggesting that smell wasn’t all that important. Conversely, olfactory bulbs grew to become very large in later sauropods and other closely related giant dinosaurs.

A strong sense of smell is associated with complex social behavior in many species. Alternatively, olfactory capabilities play an important role in foraging, and helping herbivores to distinguish between digestible and indigestible plants.

In time, Buriolestes transitioned to a plant-eating diet, which explains why its brain-to-body size ratio actually decreased. Carnivorous animals generally need more cognitive power in order to detect prey, as well as other predators. For slow-moving sauropods, brainpower wasn’t at such a premium.

Indeed, when the researchers calculated Buriolestes schultzi cognitive capability based on its brain volume and body weight, they found higher values than those seen in giant sauropods. However, the cognitive value was lower than that of theropod dinosaurs, suggesting that Buriolestes wasn’t smarter than T. rex or Velociraptor.

Our knowledge of very early dinosaurs is lacking, most paleontologists agree. This is why this study is so important, offering a rare window into the evolution of the brain and sensory systems of one of the earliest dinosaurs, and later some of the largest animals ever to walk on land.

The findings appeared in the Journal of Anatomy.

Researchers use math to tell how lady dinosaurs were different from their male counterparts

Let’s face it, math isn’t the coolest subject out there — because nothing is cooler than dinosaurs. New research, however, is using the former to get a better understanding of the latter.

A Maiasaura skeleton at the Brussels Natural History Museum.
Image credits Vladimír Socha via Wikimedia.

We refer to physical differences between males and females of the same species as ‘sexual dimorphism”. This doesn’t include differences in their reproductive organs or genetic material, which is what separates the sexes by definition, but rather things like height, body proportions, the coloring on fur or feather, or secondary sexual characteristics (such as beards or breasts).

Virtually all complex organisms exhibit sexual dimorphism in one way or another. Most commonly it has something to do with attracting a mate and making as many babies as possible. Dinosaurs, a team of statisticians tells us, likely had such differences too.

Dinosaur dating, with math

“It’s a whole new way of looking at fossils and judging the likelihood that the traits we see correlate with sex,” says Evan Saitta, a research associate at Chicago’s Field Museum and the lead author of the new study.

“This paper is part of a larger revolution of sorts about how to use statistics in science, but applied in the context of paleontology.”

The issue with identifying sexual dimorphism in fossils is that they don’t preserve almost any information on soft tissues (where most of these differences lie). Furthermore, this lack of data makes it even harder to tell which of the differences we do see in fossils are owed to sexual dimorphism, and which to variation between closely-related species and subspecies.

A new paper uses statistical analysis to work around the issue. Since the data we can obtain from fossils themselves is incomplete, and judging them by the species living today can yield a lot of false results, the team turned to a technique called effect size statistics instead of more traditional approaches. In a nutshell, this technique is applicable to smaller datasets and estimates the degree of sex differences within that data; it also yields an uncertainty value about these results, so we know if the findings are reliable or not.

The actual math involved here is quite complex, as it tends to be with statistics. Suffice it to say, the team created an algorithm to process the data and then fed it measurements of dinosaur fossils. The program then returned estimates of body mass dimorphism and expected error levels. This latter value wouldn’t be calculated using other types of statistical analysis, the authors note.

“We showed that if you adopt this paradigm shift in statistics, where you attempt to estimate the magnitude of an effect and then put error bars around that, you can often produce a fairly accurate estimate of sexual variation even when the sexes of the individuals are unknown,” says Saitta.

The method is far from perfect and doesn’t tell us the complete story. For example, some of the team’s findings include a wide variation in size among the sexes for the dinosaur species Maiasaura, much more so than in others. One of the sexes grew around 45% larger than the other — that being said, the team can’t tell which one of them it was.

Despite being limited, it can go a long way to deepen our understanding of dinosaur biology. Reproduction (and its myriad branches, including sexual selection and dimorphism) is arguably the most important driver of evolution. Having a better understanding of how the dinos did it would give us a deeper look into how they lived. The ways the sexes were different from one another is a cornerstone of that.

The paper “An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa” has been published in the Biological Journal of the Linnean Society.

Researchers confirm the first case of bone cancer in dinosaurs

Evidence is mounting that, despite living hundreds of millions of years ago, dinosaurs were not strangers to cancer.

An image and computerized scan of the bone.
Image credits Royal Ontario Museum / McMaster University.

Researchers have uncovered a new dinosaur fossil that seems to have suffered from a severe form of bone cancer around 77 million years ago. The findings help underscore the fact that cancer is in no ways a modern affliction — or a human-only one — and points to the role disease and other medical conditions play in the wild.

The bad bone

The research is based on the fossils of a Centrosaurus apertus, a herbivore that lived in the Canadian stretches during late Cretaceous (76 to 75 million years ago). Its life, at least during its latter parts, was probably not very enjoyable at all, as this dinosaur had to contend with a very aggressive case of bone cancer in one of its hind legs.

Not only would this make it difficult and painful for the dinosaur to move around — either to forage or to evade/fight off predators — but the team studying its fossil believes the cancer was malignant. If so, it means it could spread to its other tissues, mainly its internal organs.

The cancer in its leg bones was so advanced, that at first the team was convinced they were looking at a bone that had healed at sutured itself after a fracture. It was only after the bone was studied in depth using a host of techniques, including radiology and orthopedic surgery, that they found a massive, aggressive tumor inside the bone.

“Diagnosis of aggressive cancer like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to properly identify,” Dr. Mark Crowther, co-author of the study, said in a statement.

“Here, we show the unmistakable signature of advanced bone cancer in 76-million-year-old horned dinosaur—the first of its kind. It’s very exciting.”

The disease had progressed to an “advanced stage” by the time the animal died and likely made it very difficult for it to move. Still, it’s not all tragedy and woe with the dino: his remains were found in a “bone bed” along with many others from the same species. The team believes we’re looking at a pack of C. apertus that died in a flood. From the lack of bite marks on the diseased dino, and from his final resting place alongside his family and friends, it’s safe to assume that the herd lifestyle allowed it to survive despite his condition.

“The shin bone shows aggressive cancer at an advanced stage. The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of the time,” adds Dr. David Evans, corresponding author of the study.

“The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease.”

This isn’t the first time we’ve found evidence of tumors in dinosaur fossils, but it is the first confirmed case of bone cancer we’ve seen in such an animal.

The finding goes to show that even the mightiest animals sometimes have to bow in the face of disease. But it also shows how far we’ve come: dinosaurs, for all their might and long reign, were at the mercy of such conditions, and we’re starting to learn how to identify, manage, and cure them.

The paper “First case of osteosarcoma in a dinosaur: a multimodal diagnosis” has been published in the journal The Lancet.

Insect-hunting dino “the size of a teacup” unearthed in Madagascar

A diminutive fossil is teaching us about how dinosaurs evolved to their impressive sizes.

3D restoration of Kongonaphon kely.
Image credits Frank Ippolito / American Museum of Natural History (AMNH).

Christened Kongonaphon kely, meaning ‘tiny bug slayer’, this dinosaur is unusually proportioned — it was about the size of a coffee cup. The dino belonged to the group which dinosaurs and pterosaurs (flying dinosaurs) eventually branched away from.

Small, but dangerous!

“There’s a general perception of dinosaurs as being giants,” says palaeontologist Christian Kammerer from the North Carolina Museum of Natural Sciences, first author of the paper describing the findings.

“But this new animal is very close to the divergence of dinosaurs and pterosaurs, and it’s shockingly small.”

The tiny dino lived on Madagascar during the Triassic period some 237 million years ago. It stood a measly 10 centimetres (about 4 inches) in height, but its extended family — group Ornithodira — would go on to evolve into the giant dinosaurs we saw in Jurassic Park.

Researchers are, understandably, keen to better chart this transition from very small to colossal, but we haven’t found many specimens from the early Ornithodira lineage.

Artist’s impression of the tiny dino.
Image credits Alex Boersma.

The current fossil was unearthed during fieldwork in 1998 at a fossil site in southwestern Madagascar alongside hundreds of other specimens. The authors say it “took some time before we could focus on these bones”, but they quickly figured out the fossil was quite unique.

This tiny dinosaur belongs to the Lagerpetidae family, an early group of the Ornithodira lineage. While all Lagerpetidae were small, this is the smallest one we’ve found so far. The team believes these diminutive sizes weren’t by accident, but by design.

“Although dinosaurs and gigantism are practically synonymous, an analysis of body size evolution in dinosaurs and other archosaurs in the context of this taxon and related forms demonstrates that the earliest-diverging members of the group may have been smaller than previously thought, and that a profound miniaturisation event occurred near the base of the avian stem lineage,” the team writes in a new paper.

The team bases this hypothesis on the teeth of the dinosaur. Their pits and abrasions suggest the animals mostly ate hard-shelled insects, a source of food larger dinosaurs wouldn’t even bother taking into consideration. It’s possible then that this ‘miniaturization event’ allowed dinosaurs to gain an evolutionary advantage by entering new ecological niches.

Along with a smaller size,  K. kely and its archosaur fellows likely also evolved traits that are hallmarks of today’s birds: new modes of bipedal movement, primitive fluff and down to keep warm, even primitive stages of flight, the researchers suggest.

The paper “A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry” has been published in the journal PNAS.

The earliest dinosaurs probably laid soft-shelled eggs

The first dinosaurs were huge softies, judging by the shells of the eggs they laid, a new study reports.

Photographs, histology and Raman spectroscopy of Protoceratops
and Mussaurus soft eggshells.
Image credits Mark A. Norell et al., (2020), Nature.

Researchers from the American Museum of Natural History and Yale University analyzed the eggs of two different non-avian dinosaurs to find that they resemble those of turtles in terms of microstructure, composition, and mechanical properties.

Meaning that early dinosaurs likely laid soft-shelled eggs. Under pressure from predators or the environment, dinosaurs evolved hard-shelled eggs at least three independent times, the team adds.

Getting an egg up

“The assumption has always been that the ancestral dinosaur egg was hard-shelled,” said lead author Mark Norell, chair and Macaulay Curator in the Museum’s Division of Paleontology. “Over the last 20 years, we’ve found dinosaur eggs around the world. But for the most part, they only represent three groups — theropod dinosaurs, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods.”

“At the same time, we’ve found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren’t their eggs preserved? My guess — and what we ended up proving through this study — is that they were soft-shelled.”

Amniotes are a group of animals including birds, mammals, and reptiles, which reproduce by laying eggs with an inner membrane or “amnion”. This membrane helps keep the embryo from drying out. Some amniotes, the team explains, including many turtles, lizards, and snakes, lay soft-shelled eggs, whereas others (mostly birds) lay hard-shelled eggs. Their hardness comes from high levels of calcification in the shell.

Harder eggshells provide better protection from the environment and was a big development for amniotes, as it allowed for more eggs to survive until hatching in more varied environments.

Modern crocodilians and birds, the closest living relatives to the dinosaurs, lay hard-shelled eggs. The fact that soft-shelled eggs rarely fossilize also helped as it made it extremely difficult to study the transition from soft to hard eggshells. So, it was assumed that non-avian dinosaurs used this type of shell.

But this was not the case, a new study reports. The authors studied embryo-containing fossil eggs of Protoceratops (a sheep-sized herbivore) and Mussaurus (a long-necked, big herbivore dino).

The skeletons of six among the Protoceratops embryos have been preserved surrounded by a black-and-white, egg-shaped halo, according to the team. Two of them (potentially hatched) were largely free of this halo. A closer analysis showed that the shapes were created from chemically-altered residues of the membrane lining the inside of all modern archosaur eggs. The same was true for the Mussaurus embryos.

Comparing the minerals that made up these shells with those in the eggshells of modern species, the team determined that the Protoceratops and Mussaurus eggs were indeed non-biomineralized, meaning they were leathery-soft.

“It’s an exceptional claim, so we need exceptional data,” said study author and Yale graduate student Jasmina Wiemann. “We had to come up with a brand-new proxy to be sure that what we were seeing was how the eggs were in life, and not just a result of some strange fossilization effect.”

“We now have a new method that can be applied to all other sorts of questions, as well as unambiguous evidence that complements the morphological and histological case for soft-shelled eggs in these animals.”

Using chemical composition data and the mechanical properties of eggshells from 112 other extinct and living relatives, the team determined that calcified eggs evolved independently at least three times in dinosaurs, probably from a soft-shelled type.

Soft eggshells are more sensitive to water loss and offer little protection against mechanical stress, so Protoceratops and Mussaurus probably buried them in sand or soil and incubated them with heat from decomposing plant matter, as some reptiles do today.

The paper “The first dinosaur egg was soft” has been published in the journal Nature.

Asteroid that killed the dinosaurs hit at “deadliest possible” angle

New simulations from Imperial College London reveals that the gigantic lizards of old had the worst possible luck when the asteroid hit.

Image credits Ruben / Flickr.

The team’s work shows that the asteroid hit our planet at an angle of around 60 degrees, an incidence angle that caused the largest possible quantity of climate-altering gases to be released into the atmosphere. The impact vaporized billions of tons of sulfur, the team estimates, which blocked incoming sunlight and effectively plunged the Earth into a nuclear winter that killed 75% of life on the planet.


“Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the north-east,” says Professor Gareth Collins, of Imperial’s Department of Earth Science and Engineering, lead author of the paper describing the findings.

“We know that this was among the worst-case scenarios for the lethality on impact, because it put more hazardous debris into the upper atmosphere and scattered it everywhere — the very thing that led to a nuclear winter.”

The team used 3D impact simulations and geophysical data recovered from the site of the impact, now known as Chicxulub, to piece together the 66 million-year-old event.

They looked at the subsurface structure and shape of the impact crater and then simulated impact scenarios to see what combination of angle and direction would create a site that matched with Chicxulub. By using rock cores drilled from the crater, they could gauge the forces generated by the asteroid impact, helping them better control the simulation scenarios.

Another key piece of information was obtained by comparing the geometry of the crater to subsurface structures some 30 km beneath the crater. The relationship between the two — both created by the impact — helped the team estimate the direction of the impact and the incoming angle. These two structures were aligned in a southwest-northeast direction, the authors found.

The location Chicxulub.
Image credits Demetia / Flickr.

Simulated impacts at an angle of 60 degrees reproduced all of these observations almost exactly, they add.

That the upper geological layers around the Chicxulub crater (in present-day Mexico) contain a large amount of porous carbonate rocks, evaporite rocks, and are rich in water. Under the extreme conditions created by an asteroid impact, such rocks would have decomposed to release immense quantities of carbon dioxide, sulphur compounds, and water vapor into the atmosphere.

Sulphur, in particular, has a very strong and quick-acting cooling effect on climate (that’s why large volcanic eruptions can create cold stretches of time). Sulphur aerosols block incoming sunlight, which not only reduces the amount of heat incoming to the surface but also interferes with photosynthesis. The combination of climate upheaval and lack of food then leads to massive extinction events.

The incoming angle of 60 degrees was the worst possible scenario seen in the simulations, as it maximized the transfer of energy from this impact into adjacent rocks — in other words, it was the perfect angle to throw as much of them into the atmosphere as possible.

“Large craters like Chicxulub are formed in a matter of minutes, and involve a spectacular rebound of rock beneath the crater,” says co-author Dr. Thomas Davison, also of Imperial’s Department of Earth Science and Engineering. “Our findings could help advance our understanding of how this rebound can be used to diagnose details of the impacting asteroid.”

The team hopes that their findings can help us better understand why the impact proved so deadly and that they can help us better piece together the characteristics of past impact events and the asteroids responsible for them just by looking at the craters they formed.

The paper “A steeply-inclined trajectory for the Chicxulub impact” has been published in the journal Nature Communications.

Paleontologists find 10-meter-long megaraptor in Argentina

It’s not just football that Argentina is famous for. The country is packed with dinosaurs’ fossils, with 80 species found so far in its territory. That’s 10% of the 800 that have been discovered across the world. Half of all known species have been found in Argentina, the US, China, and Mongolia. Now, a new species has been added to the roster.

Artist impression of a megaraptor. Credit Wikipedia Commons

Following two weeks of excavations, a group of paleontologists found a new megaraptor in the south of Argentina, specifically in the province of Santa Cruz. The specimen measured about 10 meters (33 feet) in length, which makes it one of the largest megaraptors found so far.

In a statement, the team said that the remains date back 70 million years – towards the end of “the age of the dinosaurs”. Fernando Novas, who was involved in the excavations, told Reuters news agency that “this new megaraptor that we now have to study would be one of the last representatives of this group” before the dinosaurs became extinct.

Megaraptors were large predatory dinosaurs that prospered during the Cretaceous period, primarily in the southern hemisphere (remains were also found in Australia and Asia) until the mass extinction that happened approximately 65 million years ago.

“Unlike the Tyrannosaurus rex, the megaraptors were slimmer animals, more prepared to run, with long tails that allowed them to maintain balance. They had muscular legs to be able to take long steps,” said in a statement Mauro Aranciaga Rolando, a fellow at the Argentine Museum of Natural Sciences (MACN).

Megaraptors had several characteristics that made them particularly lethal. According to Aranciaga, their main weapons were their extremely long and muscular arms. They also had claws on their thumbs, which had a sharp edge and could reach 40 centimeters in length.

Researcher Fernando Novas said that this new discovery will allow paleontologists “to know how these dinosaurs were in this corner of Patagonia and to know their relationships with the megaraptors found in other parts of the world.” Novas discovered the first specimen of this group of dinosaurs in 1996 and gave them their name.

The smallest specimens of megaraptors so far found measured about five meters, while the largest reached lengths similar to this specimen found in Argentina. To extract the fossils, which were locked in extremely hard rock, it was necessary to use appropriate machinery such as a rock cutter.

In a task that took about two weeks, with chisels and hammers, paleontologists removed the rock surrounding the specimen in order to remove each of the fossilized bones. The rock that contained the fossil was covered with plastic and bandages and transported to Buenos Aires, the capital of Argentina.

The formidable predator is now under quarantine at the Natural Sciences Museum in Buenos Aires, waiting for the researchers to continue with their preparation and study. After being fully described, the fossils will make their trip back to the province of Santa Cruz to enrich the collections of the “Padre Molina” Museum.