Scientists studying the newly described ichthyosaur Jabalisaurus tethyensis have gained a remarkable insight into its diet. A beautifully preserved fossil from southern Germany contains evidence of the animal’s last meals. In addition, the specimen preserves important details of the skeleton and body outline.

The fossil, specimen number JME-SOS-08369, was previously assigned to Aegirosaurus. However, researchers have now referred it to Jabalisaurus tethyensis. This specimen helps palaeontologists understand how this Late Jurassic ichthyosaur lived.

To read our recent article outlining the reassessment of Aegirosaurus fossil material to J. tethyensis: A New Species of Jabalisaurus Links Germany to Mexico.

Evidence of the Jabalisaurus Diet

JME-SOS-08369 preserves material interpreted as gastric contents. A small concentration of ganoid scales occurs in the anterior dorsal region of the body. The researchers interpret these remains as the partially digested remains of small ray-finned fishes. Therefore, scientists have direct evidence of the Jabalisaurus diet. This ichthyosaur consumed relatively small fishes.

The evidence also agrees with the anatomy of the skull. Jabalisaurus tethyensis had a slender skull armed with numerous relatively small teeth. Such jaws were well suited to catching small, active prey.

Jabalisaurus tethyensis, referred specimen JME-SOS-08369. A, overview photograph, box ‘G’ indicates the location of the preserved gastric contents, arrowhead indicates location of ischiopubis (not easily visible under natural light); B, close-up of skull; C, close-up of dentition. Picture credit: Maxwell, Neumann and Serafini.

Picture credit: Maxwell, Neumann and Serafini

The photograph of JME-SOS-08369 (above) shows the position of the preserved gastric contents. Close-up images also reveal details of the skull and dentition.

A Late Jurassic Hunter of Fish

The gastric contents provide rare direct evidence concerning the diet of a Late Jurassic ichthyosaur. Although ichthyosaurs have an extensive fossil record, direct evidence of what Late Jurassic species ate is surprisingly scarce. Other specimens have yielded fish remains and cephalopod hooklets. However, the gastric contents of JME-SOS-08369 add important information about the feeding ecology of Jabalisaurus tethyensis.

The researchers conclude that its diet included small ganoid-scaled actinopterygian fishes. These are ray-finned fishes characterised by distinctive scales covered with a hard, enamel-like substance.

A new life reconstruction (below) depicts Jabalisaurus tethyensis swimming close to the surface and pursuing halecomorph fishes. These are common Late Jurassic ray-finned fishes.

Artistic reconstruction of Jabalisaurus tethyensis, depicted in the water column close to the surface while pursuing halecomorph fishes. Picture credit: Giovanni Serafini.

Picture credit: Giovanni Serafini

The illustration provides a glimpse of this small ichthyosaur hunting in the warm waters associated with the ancient Tethys Ocean.

Examining the Jabalisaurus Skeleton

JME-SOS-08369 provides other important anatomical information. For example, the forelimbs preserve polygonal phalanges. These small bones formed part of the animal’s paddle-like limbs.

Both the right and left forelimbs preserve this distinctive polygonal morphology. Furthermore, ultraviolet light helped the researchers examine the ischiopubis, part of the pelvic region that is difficult to distinguish under natural light.

Jabalisaurus tethyensis, referred specimen JME-SOS-08369. A, phalanges from the right forelimb, with arrow indicating polygonal morphology; B, phalanges from the left forelimb, also showing polygonal form. C, ischiopubis, photographed under UV-light. Picture credit: Maxwell, Neumann and Serafini.

Picture credit: Maxwell, Neumann and Serafini

These anatomical characteristics helped the researchers compare JME-SOS-08369 with other Late Jurassic ichthyosaurs.

An Exceptionally Important Ichthyosaur Fossil

This specimen has already played an important role in studies of ichthyosaur soft tissues. Previous research examined its exceptionally complete body outline. The fossil even contributed to research suggesting that ichthyosaurs possessed an insulating layer of blubber. Now, JME-SOS-08369 has helped scientists investigate the anatomy, taxonomy and feeding behaviour of Jabalisaurus tethyensis.

To read more about this research: Ichthyosaurus Had Blubber According to New Research.

The fossil demonstrates how much information can be preserved in the fine-grained deposits of southern Germany. Bones reveal the animal’s anatomy, while traces of soft tissues help reconstruct its body. Remarkably, the contents of its digestive system provide evidence of what it ate.

Learning More About Jabalisaurus tethyensis

Everything Dinosaur recently reported the formal description of Jabalisaurus tethyensis (see link in this article). Fossils assigned to this species had previously been included within Aegirosaurus. Their reassessment has increased the known diversity of Late Jurassic ichthyosaurs from the German Plattenkalk deposits.

The discovery of Jabalisaurus in Europe is significant for another reason. Before this research, the genus was known only from Mexico. Its presence on both sides of the ancient Tethys region supports the idea of a distinctive Peri-Tethyan ichthyosaur fauna.

However, JME-SOS-08369 tells a more intimate story. Around 149 million years ago, this marine reptile hunted small fishes in a tropical sea. Thanks to exceptional fossil preservation, evidence of its prey has survived to the present day.

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

The scientific paper: “Late Jurassic ichthyosaurs from southern Germany” by Erin E. Maxwell, Jule Neumann and Giovanni Serafini published in Palaeontologia Electronica.

The award-winning Everything Dinosaur website: Models of Ichthyosaurs and Other Marine Reptiles.

Palaeontologists have named a new species of theropod dinosaur from New Mexico. The dinosaur, Dinevenator robustus, lived around 73 million years ago (Campanian faunal stage of the Late Cretaceous). Researchers identified the dinosaur from a fossil skull bone (a frontal) found in north-western New Mexico. It represents a new genus and species of troodontid.

Troodontids were lightly built, theropod dinosaurs closely related to birds. They also possessed relatively large brains compared to many other dinosaurs. The discovery of Dinevenator robustus provides new information about troodontid diversity in Late Cretaceous North America.

The research was undertaken by Dr Steven E. Jasinski and Dr Robert Sullivan. Their study was published in the scientific journal “Fossil Studies” earlier this month.

Dinevenator robustus life reconstruction. The newly described, large troodontid has caught a mammal. Whilst rare, the De-na-zin Member of the Kirtland Formation has recorded fragmentary remains of metatherian mammals. Picture credit: Sergey Krasovskiy.

Picture credit: Sergey Krasovskiy

A Large Troodontid Theropod Dinosaur

Although scientists have found very little fossil material, Dinevenator (pronounced Din-ee-ven-nay-tor), may have been surprisingly large for a troodontid. Comparisons with the skull bones of related dinosaurs suggest a body length of around 2.4 to 3 metres. Researchers estimate that it weighed approximately 68 to 136 kilograms. Therefore, Dinevenator robustus ranks amongst the larger troodontids currently known.

Palaeontologist Dr Steven Jaskinski, from the New Mexico Museum of Natural History and Science (NMMNHS) and corresponding author of the study commented:

“This really helps us get a clearer picture of the diversity in this family of dinosaurs during the Late Cretaceous in North America, and it adds to our knowledge of dinosaurs that once roamed New Mexico.”

The discovery of this new dinosaur helps clarify troodontid diversity during the Late Cretaceous. Furthermore, it increases our knowledge of New Mexico’s dinosaur biota.

Dinosaurs of the Kirtland Formation

Dinevenator robustus lived on a subtropical floodplain approximately 73 million years ago. It shared this environment with a remarkable variety of dinosaurs. For example, the crested lambeosaurine hadrosaur Parasaurolophus tubicen inhabited the same ecosystem. Armoured ankylosaurs and horned ceratopsians also roamed the region.

To read a recent blog post about the discovery of new lambeosaurine from Alberta, Canada: A New Lambeosaurine Hadrosaur from Alberta.

In addition, dome-headed pachycephalosaurs lived alongside agile dromaeosaurids. Huge tyrannosaurs represented some of the ecosystem’s largest predators. Consequently, the discovery adds another dinosaur to an already diverse Late Cretaceous fauna.

The left frontal of Dinevenator robustus (holotype) specimen number SMP VP-1955 shown in dorsal view (left) and ventral view (right). Picture credit: Sullivan (New Mexico Museum of Natural History and Science).

Picture credit: Sullivan (New Mexico Museum of Natural History and Science)

A Fossil Discovered in 2005

The fossil that eventually led to the new dinosaur’s identification was discovered more than twenty years ago. Dr Robert Sullivan found the specimen during the summer of 2005. He was collecting Cretaceous fossils in New Mexico’s San Juan Basin. The fossil came from the De-na-zin Member of the Kirtland Formation. Sullivan had discovered part of the skull of a relatively small theropod dinosaur. Initially, researchers thought the bone belonged to a dromaeosaur.

Dromaeosaurids include famous dinosaurs such as Velociraptor. However, subsequent research demonstrated that the specimen belonged to a troodontid.

Scientists have recently learned much more about North American troodontids. For instance, studies of Albertavenator from Alberta provided important comparative information. Research into Xenovenator from northern Mexico also helped scientists reassess the New Mexico fossil.

A phylogenetic analysis was conducted on a modified dataset, recovering Dinevenator robustus in a clade of robust troodontins (Troodontini) as the basal-most taxon and as the sister taxon to (Albertavenator curriei and Xenovenator espinosai). The recognition of a distinct, large, robust-skulled troodontid also increases the known diversity of theropod dinosaurs from the southern United States and provides further evidence for dinosaurs that are unique to the Kirtlandian faunas of New Mexico during the Late Cretaceous.

To read Everything Dinosaur’s blog post from 2017 about the discovery of Albertavenator: Albertavenator – Something to Get Your Teeth into.

Identifying Dinevenator robustus

Scientists have named this dinosaur from just one fossil skull bone (frontal). This bone forms part of the upper surface of the skull. Despite the limited material, the fossil preserves distinctive anatomical characteristics. Most notably, the frontal is thicker than equivalent bones in many related troodontids. Researchers also identified other features that distinguish the specimen.

These anatomical differences supported the establishment of a new genus and species. The fossil currently resides at the State Museum of Pennsylvania. However, plans are being made to transfer it to the New Mexico Museum of Natural History and Science.

Understanding Troodontid Diversity

The discovery of D. robustus increases the known dinosaur diversity of New Mexico. More importantly, it provides another piece of the complex troodontid evolutionary puzzle.

Palaeontologists continue to reassess fragmentary fossils as new discoveries provide additional comparative material. As a result, specimens collected decades ago can reveal entirely new dinosaur species.

Dr Anthony Fiorillo, Executive Director of the New Mexico Museum of Natural History and Science, highlighted this dynamic process stating:

“This new work illustrates the dynamic nature of dinosaur studies as we continue to test what we think we know. Furthermore, it demonstrates that New Mexico clearly has a prominent place in those global conversations.”

Everything Dinosaur acknowledges the assistance of a media release from the New Mexico Museum of Natural History and Science in the compilation of this article.

The scientific paper: “Dinevenator, a New Genus of Troodontid Dinosaur from the Late Cretaceous of New Mexico” by Steven E. Jasinski and Robert M. Sullivan published in Fossil Studies.

The award-winning Everything Dinosaur website: Models of Troodontids and Other Dinosaurs.

A team of international researchers have described a new dinosaur based on fossils found in Zimbabwe. This newly described sauropodomorph named Musango matusadonaensis lived during the Late Triassic (Norian faunal stage), around 210 million years ago. Musango is the fifth dinosaur to be named from fossils discovered in Zimbabwe. Furthermore, these fossils further support the idea of distinct dinosaur communities in southern Africa during the Late Triassic. Previously, scientists had thought that there were close faunal and biostratigraphical links between the Late Triassic vertebrate faunas of Zimbabwe and South Africa. Currently, no dinosaur taxa are shared between the Triassic-aged sedimentary units in Zimbabwe and those of the main Karoo Basin of South Africa and Lesotho.

A life reconstruction of the fifth dinosaur to be named from fossils found in Zimbabwe (Musango matusadonaensis). Picture credit: Mark Witton.

Picture credit: Mark Witton

The fossils were discovered on the shores of Lake Kariba in northern Zimbabwe. Moreover, the find provides fresh evidence that southern Africa preserves an important record of early dinosaur evolution.

Musango matusadonaensis – A New Member of the Sauropodomorpha

Musango matusadonaensis is classified as an early member of the Sauropodomorpha, a group of dinosaurs that eventually gave rise to giant, long-necked herbivores such as Brachiosaurus and Diplodocus. However, unlike its enormous descendants, M. matusadonaensis was a relatively small, lightly built dinosaur that probably walked on two legs. The fossils were found in association with each other but not articulated. The material consists of a partial skeleton consisting of five dorsal vertebrae, two sacral vertebrae, a left scapula and coracoid along with a partial left ilium; a right pubis and elements from the limbs. In addition, several indeterminate bone fragments were recovered.

The absence of a femur makes size estimation difficult.  However, based on comparisons with other Late Triassic sauropodomorphs, the specimen (NHMZ 2583) represents a four and a half metre long individual.  This dinosaur is estimated to have weighed around 220 kilograms.

Musango matusadonaensis silhouette showing known fossil material. Scale bar equals 1 metre. Picture credit: Brandon Stuart with additional annotation by Everything Dinosaur.

Picture credit: Brandon Stuart with additional annotation by Everything Dinosaur

While the skull has not yet been found, researchers believe that Musango was probably herbivorous or perhaps omnivorous.

Revealing Ancient African Ecosystems

The Late Triassic was a pivotal period in Earth’s history. Dinosaurs had evolved, but they had not yet become the dominant terrestrial vertebrates they would be during the Jurassic and Cretaceous. For many years, scientists assumed that dinosaur faunas across southern Africa were broadly similar. However, discoveries from Zimbabwe are beginning to challenge this long-held view.

Professor Paul Barrett, Merit Researcher at the Natural History Museum, London, and the study’s lead author, commented:

“Until recently, it was assumed that the dinosaurs living across southern Africa were largely the same. However, these discoveries are showing that this part of the ancient supercontinent Gondwana was actually made of a series of smaller ecosystems – each with a different cast of characters.”

Professor Paul Barrett (London Natural History Museum) carefully excavating fossil material on the shores of Lake Kariba. Picture credit: Paul Barrett.

Picture credit: Paul Barrett

The Fifth Dinosaur to be Described from Zimbabwe

The first dinosaur to be named from Zimbabwe was the coelophysoid “Syntarsus” rhodesiensis which was formally named and described in 1969. However, the genus name was already assigned, so it was moved to the genus Megapnosaurus, although the fossils may represent a species of Coelophysis.

The five dinosaurs known from Zimbabwe:

1. “Syntarsus” – Megapnosaurus (possibly Coelophysis) – a small theropod dinosaur.
2. Vulcanodon karibaensis – a primitive sauropod.
3. Mbiresaurus raathi – a basal sauropodomorph named in 2022 that is geologically older than Musango matusadonaensis (Griffen et al).
4. Musankwa sanyatiensis – a basal sauropodomorph named in 2024 (Barrett et al) which was coeval with M. matusadonaensis.
5. Musango matusadonaensis (Barret et al, 2026).

To read our article from 2024 about Musankwa sanyatiensis, the fourth dinosaur to be described from Zimbabwe: A New Sauropodomorph from Zimbabwe (2024).

The discovery of several sauropodomorphs in this locality highlights the significance of southern Africa to researchers examining the evolution of the sauropod lineage.

Analysis of the Musango fossil bones indicates that the individual was around eight years old and approaching full adult size when it died. Interestingly, the skeleton also preserves evidence that the dinosaur survived a serious injury or infection during its lifetime. This suggests it recovered successfully before eventually dying from another cause.

Life in an Ancient River Ecosystem

During the Late Triassic, the landscape of present-day Zimbabwe looked very different from today. Rivers and streams crossed the region, supporting a wide range of plants and animals. Musango matusadonaensis shared its habitat with lungfish, crocodile-like phytosaurs and other dinosaurs, including Musankwa sanyatiensis. As fieldwork continues, researchers expect many more species to emerge from these fossil-rich rocks.

Professor Paul Barrett believes these discoveries are only the beginning:

“It suggests that what we’ve found so far is only the tip of the iceberg. We’ve already got one other new species that we’ve yet to describe, while our team has been told about other fossils from the region that we’ve yet to look at. I think it’s likely there are even more dinosaurs still to be found there.”

The ilium of the newly described sauropodomorph from Zimbabwe (Musango matusadonaensis). Picture credit: Brandon Stuart.

Picture credit: Brandon Stuart

An International Scientific Collaboration

The research forms part of an ongoing collaboration between scientists from Zimbabwe, South Africa and the United Kingdom. Together, they are exploring regions that have received relatively little palaeontological attention compared to Europe, China and North America. As a result, these discoveries are helping fill important gaps in the fossil record. They also demonstrate that Africa played a significant role in the early evolution and diversification of dinosaurs.

Professor Jonah Choiniere, leader of the expedition and a co-author from Johannesburg’s Evolutionary Studies Institute, explained:

“New dinosaur species like Musango show the value of doing palaeontological fieldwork in remote, and often scenically beautiful, places. This study is the result of a thriving international collaboration between the UK, South Africa and Zimbabwe, and reinforces the importance of southern Africa in understanding dinosaur diversity.”

Musango matusadonaensis Etymology

The name of this new dinosaur reflects both the local language and the discovery site. Musango comes from the ChiShona language and means “living in the bush”, referring to the remote location where the dinosaur was unearthed. Meanwhile, the species name honours the nearby Matusadona National Park.

The discovery of the fifth dinosaur from Zimbabwe adds another important piece to the puzzle of dinosaur evolution. Moreover, it highlights the scientific importance of the country’s fossil record. As exploration continues, palaeontologists hope that many more prehistoric species will emerge from this remarkable part of Gondwana.

Everything Dinosaur acknowledges the assistance of a media release from the London Natural History Museum in the compilation of this article.

The scientific paper: “A new sauropodomorph dinosaur from the Pebbly Arkose Formation (Upper Triassic: Norian) of Kariba, Zimbabwe” by Paul M. Barrett, Jennifer Botha, Lara Sciscioe, Brandon P. Stuart, Jack Lovegrove, Darlington Munyikwa, Michel Zondo, Timothy J. Broderick, Steve F. Edwards, Edward Mbambo, Kimberley E. J. Chapelle, Kathleen N. Dollman, Steve Tolan and Jonah N. Choiniere published in the Journal of Systematic Palaeontology.

The award-winning Everything Dinosaur website: Sauropod Models and Dinosaur Figures.

Could giant sauropod dinosaurs stand up on their hind legs? A newly published study has explored this long-debated question using advanced digital biomechanical modelling. The research suggests that although many sauropods were capable of rearing up, the largest species probably found it much more difficult to maintain this posture.  The paper published as an open-access article in the journal “Palaeontology”, is the first to use finite element analysis (FEA) to examine sauropod rearing behaviour.

A model depicting a rearing Diplodocus.  This is the 2020 CollectA Age of Dinosaurs rearing Diplodocus model. Previous studies (Mallison, 2011) had proposed that Diplodocus with its centre of mass located posteriorly may have been able to rear up more easily than other taxa. However, these results provide no strong evidence to indicate that rearing was a frequent behaviour for Diplodocus. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Sauropods, such as Diplodocus, Giraffatitan, Dreadnoughtus and Patagotitan, were the some of the largest terrestrial animals to have ever lived. Their immense size, long necks and pillar-like limbs have fascinated palaeontologists for more than a century. One of the enduring questions surrounding these giants is whether they could raise themselves into a bipedal or tripodal stance. Sauropod rearing behaviour may have occurred to permit them to reach higher branches in trees to feed. In addition, adopting a rearing pose may have helped to intimidate rivals or to defend themselves from carnivorous theropods. Perhaps rearing behaviour could have played role in social display, courtship or mating.

A Haolonggood Sauroposeidon figure depicted in a tripodal rearing pose.  The dinosaur’s huge weight is supported by its massive hind legs and muscular tail.  However, the new study concludes that larger sauropods were probably less capable of maintaining a rearing pose for sustained periods.

Testing Sauropod Rearing Behaviour

The new study, published in the journal Palaeontology, examined the hind limb biomechanics of seven sauropod genera representing a range of sizes and evolutionary groups. Rather than relying solely on skeletal anatomy, the researchers created detailed three-dimensional digital models of the femora (thigh bones) and subjected them to finite element analysis (FEA). This engineering technique predicts how a structure responds to forces and stresses and is widely used in the design of buildings, aircraft and vehicles.

The seven sauropod genera included in the study:

1. Amargasaurus – a dicraeosaurid known from the Early Cretaceous of Argentina estimated to have reached a length of 12 metres and weighing 5 tonnes.
2. Australotitan – of the Somphospondyli clade from the Late Cretaceous of Australia with some estimates suggesting a body length around 30 metres and weighing more than 50 tonnes.
3. Diplodocus – a diplodocid from the Late Jurassic of North America reaching a length of around 27 metres and weighing an estimated 10-20 tonnes.
4. Dreadnoughtus – a lithostrotian titanosaur from the Late Cretaceous of Argentina approximately 26 metres long and weighing 48-49 tonnes.
5. Giraffatitan – a brachiosaurid from the Late Jurassic of Tanzania estimated to reach a length of 23 metres and to weigh over 40 tonnes.
6. Neuquensaurus – a saltasaurid from the Late Cretaceous of Argentina estimated to reach a length of around 9 metres and to weigh 3.5 tonnes.
7. Uberabatitan – a lithostrotian titanosaur known from the Late Cretaceous of Brazil around 26 metres in length and weighing more than 30 tonnes.

Our detailed guide explaining whether sauropods could stand on their hind legs will be published shortly.

Two Different Femora Load Scenarios

The scientists modelled two different loading scenarios. One simulated how the femora would respond to the animal’s body weight during a rearing posture. The second incorporated the forces generated by the surrounding muscles. By comparing the stress experienced by each femur, the team assessed how well different sauropods may have coped with standing on their hind limbs.

Extrinsic functional scenario modelled in the study. A, 3D rendering of the femur of Uberabatitan (CPPLIP-1238) in posterior view, with the red arrow showing the position of the applied loads. B, representation of the constraints (yellow circles) applied to all models for the extrinsic scenarios. Picture credit: Silva Junior et al. (2025), Palaeontology. Reproduced under the terms of the applicable Creative Commons licence.

Picture credit: Silva Junior et al. (2025), Palaeontology. Reproduced under the terms of the applicable Creative Commons licence.

Smaller Sauropods Had an Advantage

The results indicate that body size played a major role in determining how effectively a sauropod could rear up. Smaller species generally experienced lower levels of stress within their femora. In particular, the saltasaurid titanosaur Neuquensaurus performed exceptionally well in the simulations. Its relatively robust femur and favourable muscle attachment sites suggest that it may have been capable of maintaining a rearing posture for longer periods.

In contrast, enormous titanosaurs such as Dreadnoughtus experienced much higher levels of stress within their hind limbs. This finding suggests that although these giants may have been able to rear briefly, maintaining such a posture would have placed considerable demands on their skeleton.

Juveniles may have been more capable of rearing than adults.  This opens up the intriguing possibility of sauropod rearing behaviour permitting ontogenetic niche partitioning. Sauropods may have changed their rearing behaviour as they grew and matured.

Interestingly, the study also compared Diplodocus and Giraffatitan, two sauropods that have featured prominently in previous discussions about rearing behaviour. The new biomechanical analysis broadly supports earlier research suggesting that differences in body shape and centre of mass influenced how easily these dinosaurs could adopt an upright stance. For example, the researchers conclude that Diplodocus was more capable of rearing than a brachiosaur such as Giraffatitan. However, the stress forces in the femur were still relatively high. Therefore, the study authors postulate that rearing for a Diplodocus was not a routine or frequent behaviour.

The giant Giraffatitan brancai skeleton on display at the Museum für Naturkunde Berlin. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Sauropod Rearing Behaviour Probably More Than Just Feeding

For many years, palaeontologists have suggested that rearing allowed sauropods to browse vegetation beyond the reach of other herbivores. However, the researchers point out that this behaviour may also have served several other important functions.

Standing upright could have helped during defensive displays, combat between rivals or mating. Furthermore, the authors note that sauropods may not always have reared unsupported. Leaning against a tree while feeding, or using a mate for additional support during courtship, would have reduced the stresses acting on the hind limbs.

Finite element analysis of stress on femora with applied load of 24,500 N to sauropod femora in anterior (left) and posterior (right) views of: Amargasaurus (A); (B), Australotitan; (C), Diplodocus; (D), Dreadnoughtus; (E), Giraffatitan; (F), Neuquensaurus and Uberabatitan (G). Regions displayed in white indicate stress value that exceed the upper limit of the defined scale. Picture credit: Silva Junior et al. (2025), Palaeontology. Reproduced under the terms of the applicable Creative Commons licence.

Picture credit: Silva Junior et al. (2025), Palaeontology. Reproduced under the terms of the applicable Creative Commons licence.

To read an article exploring the wider implications of sauropod rearing behaviour: Could Sauropods Stand on their Hind Legs?

A New Perspective

This is the first study to use finite element analysis specifically to investigate sauropod rearing behaviour. As with any computer model, there are limitations. The digital reconstructions do not include the complex internal structure of bone or the cushioning effects of cartilage. Consequently, the stress values should be viewed as comparative rather than absolute.

Nevertheless, the research provides fresh insight into the lives of the largest terrestrial animals known to science. Rather than treating all sauropods alike, the study demonstrates that anatomy, body size and muscle configuration all influenced their ability to rear up. The findings suggest that some smaller sauropods may have been surprisingly agile, while the largest species were constrained by the sheer scale of their bodies.

Commenting on the research, Mike from Everything Dinosaur explained:

“Sauropods have always challenged our understanding of biomechanics. After all, there are no extant animals analogous to them. This study shows how modern digital techniques can test ideas that were once based largely on educated guesswork. It demonstrates that even among the giant sauropods, anatomy mattered, and not every species would have behaved in exactly the same way.”

The study provides another excellent example of how engineering, computer modelling and palaeontology are working together to answer questions about dinosaur behaviour that would have seemed impossible to investigate just a few decades ago.

The scientific paper: “Standing giants: a digital biomechanical model for bipedal postures in sauropod dinosaurs” by Julian C. G. Silva Junior, Gabriel S. Ferreira, Agustín G. Martinelli, Thiago S. Marinho, Felipe C. Montefeltro published in the journal Palaeontology.

Models of sauropods and other prehistoric animals: Sauropod and Other Dinosaur Models.

A remarkable trace fossil from Germany has provided the oldest known evidence of a cloaca in the mammalian lineage. The discovery helps palaeontologists better understand the evolution of early terrestrial vertebrates and fills an important gap in the fossil record. The fossil comes from the famous Bromacker fossil locality in Thuringia (Germany). Among footprints and other trace fossils the scientists identified a tail impression. The anterior portion of this tail impression preserves evidence of the earliest synapsid cloaca.

The international team of researchers, led by scientists from the Museum für Naturkunde Berlin, published their findings in the journal “iScience”. The trace fossils are approximately 294 million years old (Early Permian). This represents the first occurrence of a cloaca in the fossil record of stem mammals.

The trace fossil specimen MNG 13490 with the preserved underside of the tail impression. Note scale bar equals 10 cm. Picture credit: Marchetti et al.

Picture credit: Marchetti et al

A Rare Glimpse of Soft Tissue Preservation

Fossils usually preserve bones and teeth. Soft tissues, however, almost always decay before fossilisation can occur. Consequently, direct evidence of anatomical features such as the cloaca is exceptionally rare. The newly described specimen includes a beautifully preserved impression of the tail together with fossil footprints. Near the base of the tail, the researchers identified two rows of raised scales separated by a narrow vertical slit. They interpret these features as the lips and opening of a cloaca.

This fossil provides the first direct evidence of an earliest synapsid cloaca, offering scientists an unprecedented look at the anatomy of an animal closely related to the ancestors of mammals.

The caseid synapsid tail impression. Note scale bar equals 5 cm. Picture credit: Marchetti et al.

Picture credit: Marchetti et al

What is a Cloaca?

A cloaca is a single external opening used by the digestive, urinary and reproductive systems. Today, amphibians, reptiles and birds possess a cloaca. Among mammals, however, only monotremes such as the platypus and echidnas have retained this feature. Most extant mammals (placentals and marsupials) have separate openings for these bodily functions. Until now, scientists had little direct fossil evidence showing how this important anatomical structure appeared in the mammalian lineage.

An Early Relative of Mammals

The fossil traces have been linked to a caseid synapsid. Caseids were large-bodied, herbivorous members of the Synapsida, the evolutionary group that eventually gave rise to the Mammalia. Researchers matched the fossil impression with the distinctive Dimetropus footprints found at the Bromacker locality. Comparisons with skeletal fossils collected from the same site strengthened this interpretation.

Although caseids looked very different from mammals today, they belonged to the same broad evolutionary lineage. Therefore, this discovery provides valuable information about the early stages of mammalian evolution.

The cloacal area in the anterior part of the tail impression. Note scale bar equals 5 cm. Picture credit: Marchetti et al.

Picture credit: Marchetti et al

New study highlights the growth rates of diminutive Dimetrodon species from the Bromacker locality: Bromacker Dimetrodon Growth Study.

Why Did the Cloaca Evolve?

The study also explores why the cloaca changed during vertebrate evolution. Although the answer remains uncertain, the researchers suggest several possible explanations.

For example, changes in reproductive anatomy may have played a role. Likewise, increasingly dry environments could have influenced the evolution of different body structures. The scientists also propose that evaporative cooling through the cloacal opening may have helped animals regulate their body temperature. Furthermore, changes in body shape, including shorter tails and modified limbs, may have contributed to these evolutionary developments.

In squamates and birds, the cloaca tends to have a horizontal orientation. Cloacal evaporation for thermoregulation purposes has been observed in squamates and birds. In contrast, the Crocodylomorpha and the Caudata (salamanders and their extinct relatives), have a vertical cloaca. These animals are associated with aquatic environments. Intriguingly, the fossilised tail impression is clearly impressed in a water-saturated sediment.

The fossil specimen shows swimming traces associated with Dimetropus footprints. Therefore, it is possible that a transition from a vertical to a horizontal cloaca occurred as an adaptation to drier environments. The horizontal orientation of the cloacal orifice could favour more efficient cloacal evaporation to help maintain body temperature. This would be in agreement with the vent orientation change in stem reptiles between the Carboniferous and the Permian, in a time of global warming and increasing aridity and seasonality. Nevertheless, the causes of this correlation should be further investigated in modern taxa.

The Significance of the Bromacker Fossil Site

The Bromacker fossil locality is recognised as one of the world’s most important Late Palaeozoic fossil sites. It has produced an exceptional record of terrestrial animals and plants that lived during the Early Permian. This latest discovery also demonstrates the value of revisiting historic museum collections. Modern imaging techniques and careful re-examination can reveal important anatomical details that earlier researchers could not detect.

A false-colour depth map of the cloacal area taken from the photogrammetric 3D model. Picture credit: Marchetti et al.

Picture credit: Marchetti et al

Understanding the Evolution of Mammals

The discovery of the earliest synapsid cloaca provides much more than an anatomical curiosity. It offers scientists a rare opportunity to investigate the evolution of reproductive and excretory systems in one of the most important vertebrate lineages. As new discoveries emerge from the Bromacker site and other fossil localities, researchers will continue to refine our understanding of how the ancestors of mammals adapted to life on land hundreds of millions of years ago.

Commenting on the importance of this research, Mike from Everything Dinosaur stated:

“Soft tissue fossils are incredibly rare, so discoveries like this earliest synapsid cloaca impression are exceptionally important. The specimen shows that trace fossils can preserve anatomical details that skeletal remains alone cannot reveal. It also reminds us that remarkable scientific discoveries can still be made by re-examining specimens already held in museum collections.”

This remarkable discovery demonstrates how exceptional fossil preservation continues to reveal new chapters in the evolutionary history of the Mammalia.

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

The scientific paper: “The evolutionary significance of the earliest cloacal opening in Synapsida” by Lorenzo Marchetti, Antoine Logghe, Arnaud Rebillard, Mark J. MacDougall and Jörg Fröbisch published in IScience.

The multi-award-winning Everything Dinosaur website: Models of Prehistoric Life.

A team of international scientists has uncovered the remarkable mechanism behind seal underwater hearing. A new study, led by researchers from the London Natural History Museum reveals how extant seals hear equally well in air and underwater. The findings help to explain a long-standing evolutionary mystery and could support future conservation efforts.

The research, published as an open-access paper in the “Royal Society Proceedings B”, examined more than two hundred living and fossil seal specimens. By combining advanced CT scanning with evolutionary analysis, the researchers identified the specialised tissue that makes this extraordinary ability possible.

Blood-Filled Tissue Helps Seals Hear Underwater

Unlike humans and most other land mammals, seals can hear efficiently in two very different environments. Normally, mammalian hearing relies on an air-filled middle ear. However, this arrangement performs poorly underwater because the air pocket behind the eardrum reflects almost all sound. The researchers discovered that seals overcome this problem with specialised cavernous tissue inside the middle ear. During a dive, this tissue fills with blood. As blood has a density similar to seawater, sound passes more efficiently through the ear and reaches the cochlea. As a result, seals continue to hear clearly beneath the waves.

Lead and corresponding author Dr James Rule (London Natural History Museum/Monash University) explained that scientists have puzzled over this adaptation for decades. The new research finally identifies the anatomical feature responsible for amphibious hearing.

A 3D rendering of the skull of a Southern Elephant seal showing the underwater hearing adaptations. Picture credit: James Rule.

Picture credit: James Rule

Fossils Reveal the Evolution of Seal Underwater Hearing

The team’s analysis included both living species and fossil relatives of modern seals. Consequently, the researchers could trace when this remarkable adaptation first evolved. Evidence suggests that the ancestors of seals initially heard well only in air. Ancient species such as Potamotherium (Oligocene to Miocene) and the stem pinniped Puijila (late Oligocene to early Miocene) probably lacked effective underwater hearing. However, later marine relatives, including Enaliarctos, appear to have evolved the first form of amphibious hearing approximately 26.7 million years ago.

The earliest relatives of pinnipeds, such as the 23-million-year-old Puijila darwini, could only hear in-air. Like most mammals, their ears did not function properly underwater. Picture credit: Jaime Bran.

Picture credit: Jaime Bran

From this point onwards, different seal groups continued to refine their hearing. For example, true seals (phocids) developed enhanced underwater hearing. In contrast, the earliest eared seals retained adaptations that favoured hearing in air.

The study indicates that these improvements evolved independently after the earliest marine pinnipeds had already acquired the basic mechanism for hearing in both environments.

Rare Acoustic Abilities

The scientists also suggest that improved underwater hearing opened new evolutionary opportunities. Over millions of years, seals developed an impressive range of acoustic behaviours.

Today, some species produce haunting underwater vocalisations. Others can learn new sounds, keep a rhythmic beat and even imitate aspects of human speech. These unusual abilities may have become possible because their ancestors first evolved an ear capable of functioning effectively both above and below the water’s surface.

Life reconstruction of Enaliarctos mealsi, one of the earliest marine seals from around 23 million years ago, being chased by a cetacean. It was capable of hearing both in-air and underwater (amphibious hearing), thanks to a specialised tissue in their ears (called a cavernous tissue). However, their hearing ranges in both environments were quite limited. Picture credit: Jaime Bran.

Picture credit: Jaime Bran

Museum Collections Unlock New Discoveries

The research depended upon the Natural History Museum’s extensive collections. Scientists examined more than two hundred specimens representing a hundred and nineteen living and extinct species of Carnivora.

By studying fossil skulls alongside modern seals, the researchers reconstructed the evolutionary history of the middle ear. This work demonstrates the continuing scientific value of museum collections assembled over many generations.

Dr Natalie Cooper, Merit Researcher at the London Natural History Museum, London stated:

“The Natural History Museum has some of the best seal collections in the world, and this study really shows its value. This research simply wouldn’t have been possible without these specimens,
which have been collected across hundreds of years from all over the world. It’s important that we know how seals hear because noise pollution in the ocean is growing. As the seas get louder, it’s harder for seals to find mates and communicate with each other putting their survival at risk. By understanding how these animals hear, we can start to put solutions in place.”

To read an article from 2020 but the discovery of a prehistoric pinniped in New Zealand that re-writes seal evolution: Sealing the Fate of Pinniped Evolution.

Understanding Hearing Function Can Help Protect Seals

The discovery has important conservation implications. Oceans are becoming increasingly noisy because of shipping, offshore construction and other human activities. Consequently, underwater noise can interfere with how seals communicate, locate mates and navigate.

Understanding seal underwater hearing provides researchers with valuable information about how these animals perceive their environment. In turn, this knowledge could help shape future conservation measures designed to reduce the impact of underwater noise pollution.

Mike from Everything Dinosaur commented:

“This fascinating study shows how fossils continue to answer important questions about the evolution of living animals. By combining evidence from extinct and modern seals, the researchers have explained one of the most remarkable hearing adaptations found in any mammal.”

Everything Dinosaur acknowledges the assistance of a media release from the London Natural History Museum in the compilation of this article.

The scientific paper: “The origin and evolution of amphibious hearing in pinnipeds” by James P. Rule, Travis Park, Moganavalli Kattan, Camille Grohé, Roxana Taszus, Stephanie M. Palmer, David P. Hocking, Justin W. Adams, Alistair R. Evans, Ian G. Brennan, Tahlia I. Pollock, Daniela Sanfelice, Felix G. Marx, Naoki Kohno, Martin Sabol, Alexander Stoessel, John J. Flynn and Natalie Cooper published in the Proceedings of the Royal Society B.

The award-winning Everything Dinosaur website: Models of Prehistoric Mammals.