Newly published research demonstrates that the super-sized canines of sabre-toothed predators were “optimal” for biting into prey.  Oversized canines have evolved on several occasions within tetrapods.  Perhaps, the most famous example are the sabre-toothed cats, such as Smilodon.  There have been numerous studies into the efficiency of Smilodon teeth.  This new study, published in the journal “Current Biology”, reveals why these canines were “functionally optimal” and highly effective at puncturing prey.

The Rebor Smilodon populator 1/11th scale figure posed with its mouth open. A beautiful replica of a Sabre-toothed cat.  A newly published study (January, 2025), highlights the efficiency of the large canines for puncturing prey. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows the Rebor Smilodon populator scale model.   This model is in the “jungle” colour scheme.  The figure possesses the huge sabre-teeth associated with this big cat.  The Smilodon teeth in this figure have been beautifully crafted.

To see the range of Rebor models and figures in stock at Everything Dinosaur: Rebor Figures and Models.

Studying Smilodon Teeth and the Evolution of Sabre-teeth

The research was led by scientists at the University of Bristol in collaboration with Monash University (Melbourne, Australia).  The study demonstrates that the long, sharp blade-like teeth gave sabre-toothed predators a significant advantage when it came to capturing and subduing prey.

The findings help to explain why sabre-teeth are seen so frequently in the fossil record.  This specialist dentition has evolved independently at least five times in the Mammalia.  In 2020, Everything Dinosaur team members wrote about a research paper that explored sabre-tooth hunting methods.

To read our article about this research: Sabre-toothed Predators Evolved Different Hunting Styles.

Big-toothed predator. The skull of a Smilodon fatalis (La Brea tar pits). Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

A Possible Explanation for the Extinction of Sabre-toothed Predators

The researchers propose a possible explanation for the demise of sabre-toothed predators. Their increasing specialisation may have acted as an “evolutionary ratchet”.  They became highly efficient hunters. However, with their specialised teeth, they were more vulnerable to extinction when ecosystems changed and their prey became scarce.

The team, set out to test whether sabre-tooth shape was an optimal balance between two competing needs: sharp and slender enough to effectively puncture prey and blunt and robust enough to resist breaking. Using 3D-printed steel tooth replicas in a series of biting experiments and advanced computer simulations, the researchers analysed the shape and performance of ninety-five different carnivorous mammal teeth, including twenty-five sabre-toothed species.

Functional optimality drives the repeated evolution of extreme sabre-tooth forms. Picture credit: Dr Tahlia Pollock.

Picture credit: Dr Tahlia Pollock

Lead author of the research, Dr Tahlia Pollock from the University of Bristol explained:

“Our study helps us better understand how extreme adaptations evolve – not just in sabre-toothed predators but across nature. By combining biomechanics and evolutionary theory, we can uncover how natural selection shapes animals to perform specific tasks.”

“Dirk-toothed” and “Scimitar-toothed” Predators

This research challenged a presumption about Smilodon teeth and the dentition of sabre-toothed hunters.  Previously, scientists had grouped the canines of sabre-toothed predators into two, broad categories (ecomorphs).

These two categories are:

• “Dirk-toothed” – long, straight canines.
• “Scimitar-toothed” long, canines that have a greater curvature.

Instead, this study uncovered a spectrum of sabre-tooth shapes, from the long, curved teeth of the false sabre-toothed cat Barbourofelis fricki to the straighter, more robust teeth of the machairodont Dinofelis barlowi. This supports a growing body of research suggesting a greater diversity of hunting strategies among these predators than previously thought.

The research team hope to develop their research programme by including all tooth types. Their aim will be to explore the biomechanical trade-offs that shaped the evolution of diverse dentition across the animal kingdom.

Co-author Professor Alistair Evans (Monash University) added:

“The findings not only deepen our understanding of sabre-toothed predators but also have broader implications for evolutionary biology and biomechanics. Insights from this research could even help inform bioinspired designs in engineering.”

Everything Dinosaur acknowledges the assistance of a media release from the University of Bristol in the compilation of this article.

The scientific paper: “Functional optimality underpins the repeated evolution of the extreme ‘sabre-tooth’ morphology”  by Tahlia I. Pollock, William J. Deakin, Narimane Chatar, Pablo S. Milla Carmona, Douglass S. Rovinsky, Olga Panagiotopoulou, William M.G. Parker, Justin W. Adams, David P. Hocking, Philip C. J. Donoghue, Emily J. Rayfield and Alistair R. Evans published in Current Biology.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.

Scientists have described in detail a Rhamphorhynchus fossil from the famous Solnhofen deposits of Germany.  Most Solnhofen pterosaur fossils are pancaked, but specimen number NHMUK PV OR 37002 has been preserved in three dimensions.  This has permitted the researchers to assess how Rhamphorhynchus changed as it grew.  The fossil represents an extremely large individual. It had an estimated wingspan of approximately 1.8 metres.  When this fossil was studied over a hundred years ago, it was thought to represent a new species.  It was named Rhamphorhynchus longiceps (Woodward, 1902). However, the fossil material is now thought to represent an extremely mature Rhamphorhynchus muensteri.

The Largest Rhamphorhynchus Known to Science

The fossil material represents the largest known specimen of Rhamphorhynchus. It is exceptionally important due to the completeness of the specimen and its excellent state of preservation. In addition, as it represents the remains of a large, mature adult it can help palaeontologists to gain a better understanding of the growth of non-pterodactyloid pterosaurs, especially at upper sizes.

Furthermore, the specimen exhibits unusually flattened teeth. This suggests a change in diet for these flying reptiles as they matured.

Specimen NHMUK PV OR 37002 represents an exceptionally large and mature adult Rhamphorhynchus muensteri from the Eichstätt locality of Solnhofen. Counterplates and separate plate containing caudal series attached to the main plate are outlined in red. cdv, caudal vertebrae on separate plate and counterplate attached to main plate; hu, humerus; lwpx1, left wing phalanx 1; lwpx2, left wing phalanx 2; lwpx3, left wing phalanx 3 on counterplate; lwpx4, left wing phalanx 4 on counterplate; olwpx2, outline of left wing phalanx 2 on counterplate; olwpx3, outline of left wing phalanx 3; olwpx4, outline of left wing phalanx 4; orwpx3, outline of right wing phalanx 3; orwpx4, outline of right wing phalanx 4; orpes, outline of right pes; rad/uln, radius and ulna; rpes, right pes on counterplate; rwpx2, right wing phalanx 2; rwpx4, right wing phalanx 4 on counterplate. Note scale is 5 cm. Picture credit: Hone and McDavid.

Picture credit: Hone and McDavid.

Studying the Rhamphorhynchus muensteri Specimen

Rhamphorhynchus is one of the most extensively studied pterosaurs.  There are over a hundred specimens in museum collections.  Most of these were sourced from the remarkable Solnhofen deposits in the German state of Bavaria. The vast majority of these specimens represent juveniles and even those fossils thought to represent adults typically have a wingspan of no more than a metre. NHMUK PV OR 37002 represents a giant rhamphorhynchine. It is also amongst the largest non-pterodactyloid pterosaurs known, and certainly the most complete specimen of an animal in excess of 1.5 m in wingspan. This Rhamphorhynchus fossil helps support the theory that some pterosaur taxa in the Jurassic were capable of reaching large sizes.

Moreover, this specimen displays anatomical differences not observed in smaller individuals, providing insights into the late-stage development of this genus.

Size comparison of different Rhamphorhynchus muensteri specimens: (anti-clockwise from top left) A – the smallest known BMMS A3 (21 mm skull length), a generalised ‘typical adult’ specimen C (122 mm skull length), D the second largest known GPIT RE/7321 (150 mm skull length) and B, the largest known NHMUK PV OR 37002 (201 mm skull length). Note scale is 1 metre. Picture credit: Hone and McDavid.

Picture credit: Hone and McDavid.

Ontogenetic Niche Partitioning

The study has been published in the open-access journal “PeerJ”.  The researchers identified several changes in the anatomy of Rhamphorhynchus as it grew and matured. For example, analysis of the skull demonstrated a significant reduction in the size of the eye socket and an increase in the size of the temporal fenestra.  In addition, it was noted that NHMUK PV OR 37002 had flattened teeth, very different from the needle-like teeth found in juveniles.

Skulls of specimens of Rhamphorhynchus muensteri at different sizes. Top to bottom: (A) BSPG 1889 XI 1 (‘Exemplar 7’, skull length 35 mm per Wellnhofer, 1975), scale bar 25 mm; (B) YPM VP 1778 (‘Exemplar 33’ of Wellnhofer, skull length 90 mm, measured by SNM using ImageJ), scale bar 35 mm; (C) GPIT RE/7321 (‘Exemplar 81’, skull length 150 mm per Wellnhofer, 1975, illustration mirrored and partially adapted from Wellnhofer, 1975), scale bar 50 mm; (D) NHMUK PV OR 37002, skull length 201 mm. Picture credit: Hone and McDavid.

Picture credit: Hone and McDavid.

These characteristics illustrate a developmental transition from smaller to larger Rhamphorhynchus specimens and align with similar traits found in other large rhamphorhynchines, indicating a consistent pattern in their growth.

This would also then point to ontogenetic niche partitioning with adults and juveniles targeting different prey items. Ontogenetic niche partitioning refers to the process by which individuals of the same species or closely related species exploit different resources or habitats at different stages of their development (ontogeny).  The authors of the paper propose a dietary shift for Rhamphorhynchus as it grew and matured.  Rhamphorhynchus juveniles may have been mostly insectivorous.  As these pterosaurs grew, they become piscivorous.  The largest individuals may have shifted to other prey, or to different prey types.

Are Modern Gulls an Analogue?

Rhamphorhynchines may have moved inland as they grew and matured. Whilst still tied to water bodies, they may have become more generalist feeders.  A modern-day analogue could be gulls (Laridae).  Many types of gull prefer marine or at least aquatic systems but are capable of foraging successfully in more terrestrial systems.  If the biggest rhamphorhynchines lived inland, this might explain their absence from the fossil record.  All things being equal, a pterosaur in a marine environment probably has a great fossil preservation potential than for example, a flying reptile that lived on an inland plain.

Skull of Rhamphorhynchus muensteri NHMUK PV OR 37002 in near lateral view showing the 3D nature of the specimen (A) and restoration of the cranium and mandible in right lateral view (B). Preserved bone and teeth are in white, obscured or reconstructed portions are in grey. Note the skull has no visible sutures indicating a fully mature, adult animal. Scale is 5 cm. Picture credit: Hone and McDavid and University College London.

Large Non-pterodactyloid Pterosaurs of the Jurassic

With a wingspan estimated at around 1.8 metres, the pterosaur fossil at the centre of this new research represents one of the largest non-pterodactyloid pterosaurs of the Jurassic.  Pterodactyloids are thought to have evolved in the Jurassic and this suborder includes the biggest flying vertebrates of all time.  For example, the Azhdarchidae, the Ornithocheiridae and Late Cretaceous giants such as Pteranodon longiceps.

In the summer of 2024, we wrote an article about a pterosaur humerus found in Oxfordshire that suggested a Jurassic pterodactyloid with a wingspan in excess of three metres.

To read this article: A Giant Oxfordshire Pterosaur.

Rhamphorhynchus is a member of a more basal group of pterosaurs, although the phylogeny of the Pterosauria remains controversial.  Although, non-pterodactyloid pterosaurs did not reach the enormous size of some later pterosaurs, there is some evidence to indicate that some taxa may have had a wingspan in excess of one and a half metres.  For example, when the rhamphorhynchid Dearc sgiathanach was described in 2022 (Jagielska et al), its wingspan was thought to be greater than two metres. However, the size of D. sgiathanach remains uncertain.

A scale drawing of the large Jurassic pterosaur Dearc sgiathanach commissioned by Everything Dinosaur for a Dearc fact sheet. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The image above shows a scale drawing of the Middle Jurassic rhamphorhynchine Dearc sgiathanach, although the size of this pterosaur remains uncertain.  The drawing was commissioned for a fact sheet that accompanied sales of the CollectA Deluxe Dearc figure.

To view the range of CollectA Deluxe prehistoric animal models: CollectA Deluxe Prehistoric Life Models.

Everything Dinosaur acknowledges the assistance of Dr David Hone (Queen Mary University of London) in the compilation of this article.

The scientific paper: “A giant specimen of Rhamphorhynchus muensteri and comments on the ontogeny of rhamphorhynchines” by David W. E. Hone and Skye N. McDavid published in PeerJ.

A recently published scientific paper has challenged the validity of the theropod taxon Saurophaganax maximus.  The researchers conclude that S. maximus should be classified as nomen dubium and a new taxon of Allosaurus is proposed – Allosaurus anax. In Latin, nomen dubium translates as “doubtful name”. Essentially, this means that the Saurophaganax genus is not supported anymore.

A scale drawing of the giant allosaurid Saurophaganax maximus. Size estimates vary but fossils of this dinosaur could represent an individual animal between 12 and 14 metres long. The Saurophaganax genus is regarded as nomen dubium. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Sorting Saurophaganax maximus

In 1995, palaeontologist Daniel Chure erected the genus Saurophaganax (S. maximus) to describe an extremely large allosaurid dinosaur that had been excavated from the Kenton 1 Quarry in Cimarron County (Oklahoma) back in the 1930s. Unfortunately, the dig site was not that well supervised and mapped when the bones were originally excavated and removed. Several dinosaur taxa were present, and this may have led to confusion between what was defined as theropod and what was thought to be sauropod fossil bone.

In his research, Chure proposed that a dorsal neural arch (OMNH 1123) be declared the holotype specimen for Saurophaganax maximus. This theropod was much larger than Allosaurus fragilis and rivalled the giant megalosauroid Torvosaurus tanneri for the title of the biggest meat-eating dinosaur described to date from the Morrison Formation. Indeed, the Kenton 1 Quarry fossils were thought to represent one of the largest theropods known from the Jurassic of North America. Perhaps these fossils could be from one of the largest, Jurassic carnivorous dinosaurs that ever lived!

This new study proposes that the holotype (OMNH 1123), does not belong to a theropod.  The dorsal neural arch is reminiscent of that of a juvenile sauropod.  Other referred material such as chevrons and the atlas can’t be assigned to the Theropoda with certainty.  Since fossil material cannot be assigned to Saurophaganax, this taxon is considered not valid (nomen dubium).

Saurophaganax has a Chequered History

This dinosaur was named as Saurophagus maximus in 1941.  It was later revised to Saurophaganax maximus when it was pointed out that the genus name was already used to describe an extant bird.  Numerous unique characteristics were identified in the fossil material which had led to the establishment of a new dinosaur taxon.  For example, the postorbital bone in the skull lacking a postorbital boss and the atlas not having any facets for a proatlas. However, the 2024 re-evaluation shows that some of the elements originally used to distinguish Saurophaganax from Allosaurus are more parsimoniously referred to diplodocid sauropods found in the same quarry rather than an allosaurid.

This latest analysis eliminates many of the previously reported traits that distinguished the Kenton 1 Quarry allosaurid from Allosaurus.  The research team does not consider a distinct genus is warranted. Despite the similarity of the decisively theropod material to known species of Allosaurus, some elements feature subtle traits and characteristics that suggest they represent a distinct Allosaurus species. Therefore, the researchers conclude that S. maximus be classified as a nomen dubium and a new taxon of Allosaurus is proposed – Allosaurus anax.

The Rebor Saurophaganax maximus model has proved to be popular with collectors.  However, a recently published scientific paper questions the validity of this taxon.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows one of the Rebor Saurophaganax replicas that were introduced in 2022.

To view the range of Rebor figures and models in stock: Rebor Figures and Models.

In summary, palaeontologists historically considered this taxon to represent a species of Allosaurus or a very large allosaurid. However, a re-examination of the attributed specimens suggests that it is a chimera of multiple dinosaur genera. Some specimens likely belong to a diplodocid sauropod, while others could be reassigned to a new species of Allosaurus (A. anax).

The scientific paper: “Chimerism of specimens referred to Saurophaganax maximus reveals a new species of Allosaurus (Dinosauria, Theropoda)” by Andy D. Danison, Mathew J. Wedel, Daniel E. Barta, Holly N. Woodward, Holley M. Flora, Andrew H. Lee, and Eric Snively published in Vertebrate Anatomy Morphology and Palaeontology.

The Everything Dinosaur website: Dinosaur Toys and Models.

Newly published research suggests that volcanism did not play a major part in the mass extinction event that marked the end of the Mesozoic.  Enormous volcanic eruptions resulting in the formation of the Deccan Traps had been considered a primary trigger for the Cretaceous–Palaeogene (K–Pg) mass extinction event.  However, a new study suggests that the deposition of vast quantities of flood basalt did contribute to climate change but did not play a key role in the extinctions.  For example, the primary driver of the non-avian dinosaur extinction was probably the Chicxulub impact event.

The extinction of iconic dinosaurs such as Tyrannosaurus rex was not due to the deposition of the Deccan Traps according to new research. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Research Led by the University of Manchester

Researchers – led by the University of Manchester analysed ancient peats from Colorado and North Dakota. They were able to reconstruct the average annual air temperatures in the 100,000 years leading up to the extinction. The team included scientists from Utrecht University (Netherlands), the University of Plymouth and the Denver Museum of Nature and Science (USA).  Their data indicates that volcanic CO₂ emissions caused a slow global warming of about 3°C (Celsius) during this period.  They also discovered that there was a short, cold “snap”, a cooling of about 5° Celsius that coincided with a major volcanic eruption approximately 30,000 years before the extinction event.  This was likely due to volcanic sulphur emissions blocking out sunlight.

However, the team found that temperatures returned to pre-event values before the mass extinction, suggesting that, from the terrestrial perspective, volcanogenic climate change was not the primary cause of K–Pg mass extinction.  In summary, the climate changes caused by the immense volcanic activity were not dramatic enough to cause the non-avian dinosaur extinction.

Commenting on the significance of the team’s findings, lead scientist Dr Lauren O’Connor (Utrecht University), stated:

These volcanic eruptions and associated CO2 emissions drove warming across the globe and the sulphur would have had drastic consequences for life on earth. But these events happened millennia before the extinction of the dinosaurs, and probably played only a small part in the extinction of dinosaurs.”

Volcanism Not Directly Linked to Dinosaur Extinction

Co-author Dr Rhodri Jerrett, (Senior Lecturer in Earth Sciences, University of Manchester) explained:

“By comparison, the impact from the asteroid unleashed a chain of disasters, including wildfires, earthquakes, tsunamis, and an “impact winter” that blocked sunlight and devastated ecosystems. We believe that it was the asteroid that ultimately delivered the fatal blow.”

The ancient fossil peats that the research team analysed contain specialised cell-membrane molecules produced by bacteria.  The structure of these molecules is dependent on the temperature of their environment.  An analysis of the composition of these molecules enabled the scientists to reconstruct past temperatures.  The team built a detailed “temperature timeline” for the years preceding the non-avian dinosaur extinction.

Research team members mapping one of the layers of fossil peat analysed in the study. Left-to-right, Greg Price, Rhodri Jerrett and Lauren O’Connor conducting fieldwork at West Bijou. Picture credit: Tyler Lyson.

Picture credit: Tyler Lyson

Fellow author, Dr Tyler Lyson (Denver Museum of Nature and Science) added:

“The field areas are ~ 750 km apart and both show nearly the same temperature trends, implying a global rather than local temperature signal. The trends match other temperature records from the same time period, further suggesting that the temperature patterns observed reflect broader global climate shifts.”

Implications for Climate Change Researchers

This study helps scientists to understand how our planet responds to major disruptions.  This type of research can provide fascinating information about past events, but also could help find ways to prepare for future climate changes or natural disasters.

The research team hope to be able to apply this novel research method to reconstruct past climates at other crucial times in our planet’s history.

Everything Dinosaur acknowledges the assistance of a media release from the University of Manchester in the compilation of this article.

The scientific paper: “Terrestrial evidence for volcanogenic sulfate-driven cooling event ~30 kyr before the Cretaceous–Paleogene mass extinction” by Lauren K. O’Connor, Rhodri M. Jerrett, Gregory D. Price, Tyler R. Lyson, Sabine K. Lengger, Francien Peterse and Bart E. van Dongen published in Science Advances.

The Everything Dinosaur website: Dinosaur Toys and Gifts.

Scientists have solved a five-decade-old mystery.  A strange bone found in 1974 has been identified as part of the pelvis from a Dimetrodon (D. teutonis).  In 1974, geologist Thomas Martens discovered a fossil bone whilst exploring the famous Bromacker fossil site in the Thuringian Forest near the village of Tambach-Dietharz (Germany).  This site consists of Permian-aged deposits that have yielded a treasure trove of fossils.  The Bromacker location is regarded as one of the world’s most important locations for fossils of Early Permian animals.  It is part of the UNESCO Geopark in the region, and the Lower Permian rocks have been extensively explored and mapped.

An aerial view of the famous Bromacker fossil site in Germany. Picture credit: Jakob Stubenrauch Team Drohne.

Picture credit: Jakob Stubenrauch Team Drohne

Fossil Mystery Solved at Bromacker Fossil Site

Prior to the fossil bone discovery, tracks of tetrapods had been found at the Bromacker site. However, fossil bones were rare.  It had been thought that preservation conditions had prevented body fossils from being formed.  However, the discovery of pelvic girdle bones demonstrated that this site could yield body fossils.  As part of the current research project, the bones were digitally analysed and reconstructed by researchers at the Museum für Naturkunde Berlin.

The non-destructive CT scans and digital modelling enabled the scientists to produce three-dimensional models of the material.

Project manager Professor Jörg Fröbisch (Museum für Naturkunde Berlin) commented:

“I was particularly fascinated by the first bone find right from the start. With the help of modern and CT-based 3D methods, we were able to isolate the bone, visualise it from all sides and compare it with other finds. The scales fell from our eyes, and we immediately realised that it was the pelvis of a synapsid most likely that of Dimetrodon, a distant relative of us mammals.”

Wild Safari Prehistoric World Dimetrodon model.

The picture (above) shows a Dimetrodon model. The Dimetrodon taxon associated with the Bromacker fossil site is Dimetrodon teutonis.  The model shown is from the Wild Safari Prehistoric World series of figures.

To view this range on Everything Dinosaur’s website: Wild Safari Prehistoric World Models.

Dimetrodon teutonis

Dimetrodon teutonis was probably one of the top predators in the Bromacker palaeoenvironment. It was named and described in 2001 (Berman et al). The type specimen is MNG 10598, which consists of a set of vertebrae including elements from the distinctive sail of the Dimetrodon genus. The Bromacker fossil material represents the first record of Dimetrodon outside of North America. Dimetrodon teutonis was one of the smaller species of Dimetrodon. Scientists have estimated that it measured around a metre in length and weighed approximately twenty-five kilograms.

The species epithet is from the Latin “teutonis”. This translates as an individual of a German tribe. This is a reference to the geographic origins of the fossil material.  It remains the only species of Dimetrodon known from the Bromacker fossil site.  To date, only an isolated upper jaw, skeletal parts of a dorsal sail, a shoulder girdle and limb elements have been found at the Bromacker location. The discovery of the pelvic girdle of D. teutonis will help scientists to better understand the animal’s locomotion.

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde Berlin in the compilation of this article.

The award-winning Everything Dinosaur website: Dinosaur Toys and Models.

Researchers have concluded that the remarkable fossils associated with the Yixian Formation of north-eastern China were not caused by Pompeii-like events.  The prevailing view was that these amazing fossils, some of which are preserved in stunning detail, were formed due to violent volcanic eruptions, lahars or pyroclastic flows.  However, a team of scientists writing in the journal the “Proceedings of the National Academy of Sciences”, have challenged this hypothesis.  Instead, it is suggested that the deposition took place over a period of less than 100,000 years. Furthermore, more mundane factors were at work, such as high rainfall, causing the burrows of animals to collapse.

Study co-author Paul Olsen exploring the quarry where the first feathered non-avian dinosaur was found in 1996 (Sinosauropteryx). If these fossils had formed as a result of violent volcanic events, it would have been highly unlikely that delicate structures such as feathers would have been preserved. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Far from representing Pompeii-like catastrophes, the scientists conclude that the deposits provide a brief snapshot of normal life and death in an Early Cretaceous continental community.

The Incredible Fossils of the Yixian Formation

The Lower Cretaceous deposits of the Yixian Formation exposed in Liaoning Province (north-eastern China) were virtually unexplored until the 1980s.  Villagers reported finding beautiful fossil specimens, representing all kinds of creatures that once lived in a forested environment that contained large lakes.  The rocks are believed to be around 125 million years old (Barremian faunal stage). Fossils of dinosaurs, pterosaurs, birds, mammals, amphibians, reptiles, fish and insects have been found.  Some of the most famous fossils ever found come from this part of China.

Since the first, remarkable discoveries there has been fossil gold rush with an extensive network of fossil dealers and retail outlets springing up. Both locals and scientific field teams have excavated the area so much, the dig sites can be seen from space.  These are perhaps the most extensive palaeontological excavations on Earth.

The corpse of a feathered dinosaur lies on the lake shore whilst a pair of Psittacosaurus wander past and pterosaurs fly overhead.  It had been thought that the beautiful fossils of the Yixian Formation were formed as a result of volcanic activity. Picture credit: Zheng Qiuyang.

Picture credit: Zheng Qiuyang

Flattened Fossils or Three-dimensional Fossils

The fossils occur as flattened with soft tissue preservation (including feathers and melanosomes) in laminated lacustrine strata (lake sediments) or as three-dimensional almost complete, articulated skeletons in more terrestrial orientated deposits.  The discoveries include the first documented evidence of a mammal attacking a dinosaur.

To read more about this amazing fossil discovery: Repenomamus Attacks Psittacosaurus.

Co-author of the study, Paul Olsen a palaeontologist at the Columbia University’s Lamont-Doherty Earth Observatory, commented:

“These are probably the most important dinosaur discoveries of the last 120 years. But what was said about their method of preservation highlights an important human bias. That is, to ascribe extraordinary causes, i.e. miracles, to ordinary events when we don’t understand their origins. These [fossils] are just a snapshot of everyday deaths in normal conditions over a relatively brief time.”

Analysing Grains of Zircon

Lead author of the research, Scott MacLennan (University of Witwatersrand) analysed tiny grains of the mineral zircon taken from the fossil matrix and the actual fossils. With these samples, he measured the ratios of radioactive uranium as it decays into lead. This rate of radioactive decay is constant. As a result, he was able to date the material with a high degree of accuracy. These fossils were formed around 125.8 million years ago, centred around a period of less than 93,000 years.

Further calculations showed that this timeframe contained three periods controlled by variations in the Earth’s orbit when the weather was relatively wet. This caused sediments to build up in lakes and on land much more quickly than previously had been thought. Many already deceased animals were quickly buried, and oxygen that normally would fuel decomposition was sealed out. The sealing effect was fastest in lakes, resulting in the preservation of soft tissues.

This explains why two types of fossils occur.

A field team from the Nanjing Institute of Geology and Palaeontology exploring Yixian Formation exposures (Lujiatun Member). Many Psittacosaurus fossils have been found at this locality. On the right of the photograph is one of the quarries dug by local people in search of fossils to sell. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Fossil Preservation Not Connected to Volcanism

The scientists have discounted volcanism. Previous studies have suggested that some animals were entombed in lahars. These are fast-moving concrete-like slurries of mud that flow from volcanoes following eruptions. However, lahars are extremely violent, preserving animal skeletons intact, with soft tissues preserved would be most unlikely.

In addition, other researchers have suggested that the preservation occurred due to pyroclastic flows. Pyroclastic flows involve rapidly moving waves of hot ash and poisonous gases, the sort of event that led to the remarkable preservation found in Pompeii.

There are layers of volcanic ash and lava within the layers of rock that form the Yixian Formation.  However, the fossil remains include delicate structures such as feathers and stomach contents, which could not have survived such traumatic incidents.  The scientists conclude that the evidence indicates sudden burrow collapses.  For example, the famous Repenomamus attacking the Psittacosaurus, a battle preserved in time, could have occurred when the mammal invaded the dinosaur’s burrow, and the burrow subsequently collapsed.

Rather than representing multiple, Pompeii-like terrible events, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous ecosystem.

An Economy Centred Around the Yixian Formation

Whatever, the reason for the fossil preservation, Liaoning Province is now one of the most famous parts of China.  These remarkable fossils attract tourists, and an entire industry has sprung up with extensive trading in fossil souvenirs.

Potential buyers examine fossils at a shop in the city of Chaoyang (Liaoning Province), a centre of the Chinese fossil trade. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Everything Dinosaur acknowledges the assistance of a media release from The Earth Institute/Columbia Climate School (Columbia University) in the compilation of this article.

The scientific paper: “Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China” by Scott A. MacLennan, Jingeng Sha, Paul E. Olsen, Sean T. Kinney, Clara Chang, Yanan Fang, Jun Liu, Bennett B. Slibeck, Elaine Chen and Blair Schoene published in the PNAS.

The award-winning Everything Dinosaur website: Dinosaur Toys and Models.

Scientists have named a new species of oviraptorosaur from Inner Mongolia (China).  This new theropod has been named Yuanyanglong bainian.  The species name recognises that it is a hundred years since the naming of the first oviraptorosaur taxon.  In 1924, Oviraptor philoceratops was named and formally described.  Yuanyanglong is known from two fossil specimens recovered from the Lower Cretaceous Miaogou Formation.  The fossils come from the Maortu locality in Chilantai, Inner Mongolia.  Phylogenetic analysis suggests that it is a sister taxon to the clade formed by the Caenagathoidea and the Avimimidae.  It was a small dinosaur standing less than a metre high.

A scale drawing of the recently described oviraptorosaur from Inner Mongolia Yuanyanglong bainian. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Yuanyanglong bainian

The research team, writing in the academic journal Cretaceous Research identified several unique autapomorphies in the fossilised bones.  For example, the hindlimbs are proportionately elongated and they have fused lower segments.  In addition, the ilium (part of the pelvic girdle) has a much reduced postacetabular process.  This combination of anatomical traits is not known in other oviraptorosaurs, however, they are found in extant wading birds.  Yuanyanglong may have lived close to bodies of water.

One of the specimens PV02476-2 consists of a partial and poorly preserved skull.  However, the potential diet of this theropod can only be inferred at this time.  Preserved gastroliths similar to those associated with another oviraptorosaur – Caudipteryx have been recovered.  The research team have stated that preliminary observations indicate potential discrepancies in the digestion mode of early and late-diverging oviraptorosaurs.

The first part of the genus name is derived from “Yuanyang” the mandarin term for lovebirds (Aix galericulata). These birds form long bonds with their partners, a reference to the pair of skeletons found together.  The second part of the genus name “long” is a transliteration of the Chinese word for dragon.  The species or trivial name “bainian” translates as “one hundred years”, reflecting a hundred years since the naming of the first oviraptorosaur taxon Oviraptor philoceratops.

A scale drawing of a typical oviraptorosaur (O. philoceratops).  The species name of Yuanyanglong bainian commemorates the centenary of the naming of the first oviraptorosaur. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Rare Dinosaur Fossils

The Maortu locality in Chilantai, western Inner Mongolia has produced other vertebrate fossil remains.  However, dinosaur fossils are rare.  Some, as yet, undescribed sauropod remains have been reported.  In addition, three dinosaur taxa are known from this area.  A theropod has been described (Shaochilong maortuensis), along with a hadrosaurid Probactrosaurus gobiensis. In addition, fossils of an armoured dinosaur have been found. Gobisaurus domoculus was named and formally described in 2001 (Vickaryous et al).  Regarded as a member of the Ankylosauridae family Gobisaurus was a large, robust animal.  It may have been over six metres in length and weighed in excess of three tonnes.

A spokesperson from Everything Dinosaur commented that further analysis of vertebrate fossil remains from the Maortu locality would likely result in the announcing of new dinosaur taxa.

To read an article from 2016 about the discovery of a oviraptorosaur from southern China (Tongtianlong limosus) that provided new insights into oviraptorosaur radiation: A Fresh Perspective on Oviraptorosaur Radiation.

The scientific paper “A new oviraptorosaur from the Lower Cretaceous Miaogou Formation of western Inner Mongolia, China” by Mingze Hao, Zhiyu Li, Zhili Wang, Shuqiong Wang, Feimin Ma, Qinggele, J. Logan King, Rui Pei, Qi Zhao and Xing Xu published in the journal Cretaceous Research.

Visit the award-winning Everything Dinosaur website: Dinosaur Toys and Figures.

A recently published scientific paper suggests that rapid global cooling as a result of the release of billions of sulphate particles into the atmosphere played a significant role in the End-Triassic extinctions.

The end of the Triassic marks one of the five great mass extinctions recorded in the Phanerozoic Eon. Arguably, of these five, the End-Triassic extinction is the least understood by Earth scientists. The mechanisms of extinction remain open to debate. However, it is known that during this time there was extensive volcanic activity.  Pangaea began to tear itself apart, the first step in a process that led to the creation of the Atlantic Ocean. The Atlantic is still widening today.

Enormous outpourings of basaltic lava occurred covering the entire (modern) eastern seaboard of the United States, reaching as far west as Texas and probably as far south as Venezuela. These basaltic extrusions have counterparts in Europe and northern Africa that are approximately the same age. These huge eruptions are known collectively as the Central Atlantic Magmatic Province (CAMP).

A New Theory to Explain the End-Triassic Extinctions

It had been thought that huge concentrations of carbon dioxide pumped into the atmosphere led to global warming and the acidification of the world’s marine environments.  Intriguingly, a new study suggests it was sudden and dramatic global cooling that led to the extinction of many animals.

This new study suggests that the first eruptions were immense but relative brief events, lasting less than a hundred years each. Sunlight-reflecting sulphate particles were ejected into the atmosphere, rapidly cooling the planet. The extreme cold changed the biota of planet Earth. The Earth’s temperature began to rise with the increase of carbon dioxide in the atmosphere and global warming took place. However, the researchers conclude that it was the rapid freezing that resulted in the collapse of ecosystems and the initial mass extinctions.

The photograph shows red sandstone deposits in Morocco associated with the Triassic to Jurassic boundary. Red sediments in many locations around the world contain fossils of Triassic fauna and flora. The white caps are sediments laid down by extensive volcanism, as is evidenced by the grey/black basalt layers topping the assemblage. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Lead author of the paper, Dennis Kent, Adjunct Senior Research Scientist at Lamont-Doherty Earth Observatory at Columbia University, stated:

“It takes a long time for carbon dioxide to build up and heat things, but the effect of sulphates is pretty much instant. It brings us into the realm of what humans can grasp. These events happened in the span of a lifetime.”

To read another article about Triassic extinction theories: The Carnian Pluvial Episode and Extinction.

Correlating Data from CAMP Deposits

The researchers gathered data from CAMP deposits in the mountains of Morocco, in the Bay of Fundy (Nova Scotia) and from the Newark Basin (New Jersey). The focused their study on the alignment of magnetic particles within the strata. The orientation of these particles records the historical drift of the Earth’s magnetic pole during the time of the volcanic activity.

The magnetic pole is not fixed, it shifts from the planet’s stable axis of rotation—true north—and changes position by a few tenths of a degree each year. This is why compasses do not point at true north. As a result, magnetic particles in lava flows that occurred within a few decades of each other will align in the same direction, whereas those from thousands of years later could be misaligned by twenty to thirty degrees.

Red Triassic sandstones capped by volcanic ash in the Bay of Fundy (Nova Scotia). Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Five successive pulses of the Central Atlantic Magmatic Province (CAMP) lava were identified. These pulses covered a time span of approximately 40,000 years. Each lava pulse exhibited magnetic particle alignment in a single direction, suggesting that these eruptions happened within a window of around a hundred years. This is far too short a period of time for significant magnetic pole drift to occur.

The research team concluded that these eruptions released huge amounts of sulphates into the atmosphere. These particles blocked sunlight and led to global temperatures plummeting. Carbon dioxide can remain in the atmosphere for centuries. However, volcanic sulphate aerosols are dissipated within a few years. Consequently, while these volcanic winters were extreme, their duration was relatively short.

The researchers likened the CAMP episodes to the sulphate emissions from the 1783 eruption of Iceland’s Laki volcano, which triggered one of the coldest years on record and caused widespread crop failures. However, it is emphasised that the CAMP eruptions were hundreds of times more powerful.

Everything Dinosaur acknowledges the assistance of a media release from The Earth Institute/Columbia Climate School (Columbia University) in the compilation of this article.

The scientific paper: “Correlation of sub-centennial-scale pulses of initial Central Atlantic Magmatic Province lavas and the end-Triassic extinctions” by Dennis V. Kent, Paul E. Olsen, Huapei Wang and Mohammed Et-Touhami published in the Proceedings of the National Academy of Sciences.

Researchers have named and described one of the oldest dinosauromorphs known to date.  This new archosaur has been named Gondwanax paraisensis and it has been classified as a silesaurid. Controversies remain over the phylogenetic position of the Silesauridae.  They are members of the Archosauria clade but are they a sister-group to the Dinosauria or early ornithischian dinosaurs?  Silesaurid fossils are crucial for comprehending the origins and early evolution of the dinosaurs. The fossils of Gondwanax reveal a suite of characteristics that can help palaeontologists to better understand the rise of the Dinosauria.

A life reconstruction of Gondwanax paraisensis. Picture credit: Matheus Fernandes Gadelha.

Picture credit: Matheus Fernandes Gadelha

Gondwanax paraisensis

The fossilised remains were excavated from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation (Ladinian-Carnian boundary).  The fossils are thought to be around 237 million years old. Basal silesaurids have two sacral vertebrae. However, Gondwanax had three. This is the oldest occurrence of this characteristic in the fossil record. Having at least three sacral vertebrae is a defining anatomical trait of dinosaurs.

A close view of one of the vertebrae of G. paraisensis. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

The Santa Maria Formation is found in the Rio Grande do Sul region of southern Brazil. The strata represent sediments laid down in the Middle and Upper Triassic. It preserves a remarkable vertebrate fauna including cynodonts, early dinosaurs, dinosauromorphs and rauisuchians.  The Dinodontosaurus Assemblage Zone is named after the dicynodont Dinodontosaurus, which is particularly abundant.

To read more about fossil discoveries from the Dinodontosaurus Assemblage Zone: One of the Oldest Dinosauromorphs.

A view of the fossil site location. The strata here is part of the Dinodontosaurus Assemblage Zone (AZ) of the Santa Maria Formation. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

An Agile and Lightweight Animal

The researchers estimate that Gondwanax was a fast-running, agile animal. It measured around a metre in length and would have weighed between three and six kilograms.  The absence of any skull material has prevented the scientists from commenting on its diet, but it was much smaller than many of its contemporaries.  For example, the apex predator in the ecosystem was probably Prestosuchus chiniquensis. Now tentatively assigned to the Rauisuchia, P. chiniquensis measured nearly seven metres long. Gondwanax probably used its speed and agility to avoid the jaws of Prestosuchus.

The Wild Safari Prehistoric World Prestosuchus model.

The picture (above) shows a model of the fearsome Triassic predator Prestosuchus.  This figure is one of the prehistoric animals featured in the Wild Safari Prehistoric World range.

To view this range of models: Wild Safari Prehistoric World Models.

A life reconstruction of Gondwanax paraisensis (see human silhouette for scale). In addition, a skeleton reconstruction shown in lateral view (scale bar equals 50 cm) and a world map showing the approximate location of the fossil discovery. Picture credit: Matheus Fernandes Gadelha.

Picture credit: Matheus Fernandes Gadelha

Evidence of a Fourth Trochanter

The researchers are uncertain as to whether the disarticulated bones represent one animal or several individuals. The femur did reveal the presence of a fourth trochanter.  This is a knob-like protrusion located on the shaft of the femur that acted as an anchor point for muscles that helped to pull the hind leg backwards.  It is thought that the evolution of this feature on the thigh bone permitted members of the Dinosauria to develop a bipedal gait.

The author of the scientific paper, Dr Rodrigo Temp Müller commented that these anatomical features probably permitted Gondwanax to move around much more efficiently than other reptiles within the ecosystem.  The evolution of an efficient, upright gait might be one of the reasons for the eventual success and domination of the Dinosauria.

The femur of Gondwanax paraisensis. The thigh bone preserves some signs of a 4th trochanter, which is a common characteristic shared by archosaurs. It is a knob-like process that indicates muscle attachment. The researcher suggests that the presence of this anatomical feature suggests that this silesaurid had “advanced locomotor capability”. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

Fossil enthusiast Pedro Aurelio stumbled upon remains causing excitement in the scientific community at Paraiso do Sul, a location known for unearthing precursors to mammals and even a miniature crocodile species called Parvosuchus aurelioi. These fossil finds swiftly moved to the research hub at the Universidade Federal de Santa Maria’s Palaeontology Research Centre, where Dr Muller embarked on the delicate process of preparing and examining this piece of prehistoric life and carefully removing the surrounding rock matrix.

Niche Differentiation

Writing in the academic journal “Gondwana Research”, Dr Temp Müller comments that the co-occurrence of Gondwanax paraisensis and a second silesaurid (Gamatavus antiquus) in the same Assemblage Zone represents the oldest evidence of sympatry among “silesaurids” in South America. Two related species living at the same time in the same habitat.  In addition, the unique combination of sacral and hindlimb anatomical traits suggests distinct behaviours for these two species.  This could be an example of niche differentiation within the same ecosystem.

Author of the scientific paper Rodrigo Temp Müller examining fossils of Gondwanax. Picture credit: Janaína Brand Dillmann.

Picture credit: Janaína Brand Dillmann

Everything Dinosaur acknowledges the assistance of the author of the scientific paper in the compilation of this article.

The scientific paper: “A new “silesaurid” from the oldest dinosauromorph-bearing beds of South America provides insights into the early evolution of bird-line archosaurs” by Rodrigo Temp Müller published in Gondwana Research.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.

Scientists have described the smallest non-avian dinosaur eggs known to date.  The eggs, the smallest of which measures just 2.9 centimetres in length were probably laid by a small theropod.  The researchers have erected a new ootaxon Minioolithus ganzhouensis. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods.  Everything Dinosaur contacted one of the authors of the scientific paper and we were emailed an image showing this remarkable dinosaur fossil.

Minioolithus ganzhouensis the smallest non-avian dinosaur eggs discovered to date. The fossil which represents a clutch of six, tiny theropod eggs was discovered at a construction site in Ganzhou (south-eastern China). Picture credit: Shukang Zhang (IVPP).

Picture credit: Shukang Zhang (IVPP)

Minioolithus ganzhouensis

The Upper Cretaceous Ganzhou Basin exposures located in Jiangxi Province have yielded exquisite fossils of dinosaur nests, eggs and embryos. Most of these egg fossils represent oviraptorosaurs. However, troodontid, hadrosaur and potential dromaeosaurid egg fossils have also been reported. Scientists have been able to learn about dinosaur nesting and reproductive behaviours. Intriguingly, all the eggs known from these deposits were relatively large. Writing in the academic journal “Historical Biology”, the researchers describe a partial clutch with six complete small eggs. The fossil material comes from the Tangbian Formation and the eggs are thought to be around eighty million years old.

China has provided a wealth of dinosaur egg fossils.  Furthermore, the theropod egg fossils have helped to shed light on the relationship between avian and non-avian dinosaurs.  For example, a remarkable dinosaur egg fossil from southern China demonstrated the “tucking” position in an embryo. This posture is seen in the embryos of modern birds. It is a behaviour controlled by the central nervous system and it is critical for hatching success.

To read more about the remarkable theropod embryo fossil: Exquisitely Preserved Theropod Embryo Found Inside Egg.

Mike from Everything Dinosaur commented:

“This is a remarkable fossil find.  Our thanks to the research team for sharing the image with us.  Discoveries such as this are helping palaeontologists to learn more about the remarkable links between today’s birds and their theropod ancestors.”

Everything Dinosaur acknowledges the assistance of one of the scientific paper’s authors in the compilation of this article.

The scientific paper: “The smallest known complete dinosaur fossil eggs from the Upper Cretaceous of South China” by Rui Wu, Fasheng Lou, Juan Yu, Yu Xue, Shukang Zhang, Ling Yang, Wenjiang Qiu, Huimin Wang and Fenglu Han published in Historical Biology.

The award-winning Everything Dinosaur website: Dinosaur and Prehistoric Animal Models.