Scientists studying ancient fossil footprints have uncovered important evidence about the evolution of dinosaur locomotion. The research suggests that the ancestors of dinosaurs gradually changed how they walked. Over millions of years, these animals evolved from sprawling reptiles into creatures with a more upright stance. The newly published research studying dinosaur ancestors footprints provides a fresh perspective on the evolution of bipedal dinosaurs.

The international research team, led by Dr Lorenzo Marchetti of the Museum für Naturkunde Berlin, examined fossil tracks from the Italian Dolomites. Their findings have been published in the scientific journal “Palaeontology”.

Ancient Footprints from the Italian Dolomites

The researchers studied fossil footprints discovered in GEOPARC Bletterbach, part of the UNESCO World Heritage Site in the Dolomites. These remarkable tracks date from the Late Permian, before the devastating end-Permian mass extinction approximately 252 million years ago. Fossils of early archosauriform reptiles from this period are extremely rare. Consequently, fossil footprints provide valuable evidence about animals that are poorly represented in the skeletal fossil record.

The researchers reassessed the footprints and established a new trace fossil taxon, Pachychirotherium gardenaensis. This scientific name refers to the robust nature of the tracks and their geographical origins in the Gröden Valley. The footprints represent some of the earliest known evidence of archosauriform locomotion.

A trackway of an early archosauriform. The type material of Pachychirotherium gardenaensis. Scale bar equals 5cm. Picture credit: University La Sapienza of Roma.

Picture credit: University La Sapienza of Roma

From Sprawling Reptiles to Upright Walkers

By comparing Permian and Triassic footprints, the scientists reconstructed important changes in the posture of early archosauriforms. During the Late Permian, these animals generally walked with their limbs positioned outwards from their bodies. This sprawling posture resembles the stance seen in many modern lizards. However, their descendants gradually developed a more upright posture during the Triassic. By the Middle Triassic, this evolutionary transition had become well established.

Other important anatomical changes accompanied this transformation. For example, the middle toes became longer, whilst the forefeet became proportionately smaller. Furthermore, these reptiles increasingly walked on their toes rather than placing the entire foot on the ground. This type of locomotion is known as digitigrady. Birds walk on their toes, whereas humans walk on their toes and heels (plantigrade). Together, these adaptations helped early archosauriforms become more energy efficient and better runners.

A close view of the foot of the flightless bird (Rhea). Note the enlarged middle toe and that this bird walked on its toes. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Important Steps Towards Dinosaur Bipedalism

The study suggests that the evolution of upright posture, digitigrady and adaptations for running occurred gradually. These changes did not happen simultaneously. Instead, they developed over millions of years as archosauriform reptiles diversified during the Permian and Triassic. Such evolutionary innovations helped establish the anatomical foundations for bipedal locomotion in later dinosaurs and their close relatives.

For example, famous theropod dinosaurs such as Tyrannosaurus rex possessed powerful hind limbs and walked on their toes. However, the new research demonstrates that some of the fundamental adaptations associated with dinosaur locomotion originated long before the first true dinosaurs evolved.

The left metatarsal bones of a T. rex (Titus). Theropod dinosaurs walked on their toes. Note the enlarged middle toe. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Fossil Footprints Provide Unique Evolutionary Evidence

Fossilised skeletons help palaeontologists reconstruct the anatomy of extinct animals. In contrast, trace fossils preserve direct evidence of their activities. Footprints can reveal information about posture, walking style and how an animal distributed its weight.

Dr Lorenzo Marchetti emphasised the importance of these discoveries. He explained that fossil footprints preserve remarkable details about archosauriform biology and locomotion. Such evidence is especially valuable when skeletal remains are scarce.

This research highlights the scientific importance of trace fossils. Moreover, it demonstrates how the evolutionary history of dinosaurs can be traced back to their distant Permian relatives.

The Everything Dinosaur team acknowledges the assistance of the Museum für Naturkunde Berlin in the compilation of this article.

The scientific paper: “The new archosauriform track Pachychirotherium and the stepwise acquisition of digitigrady, cursoriality and erect stance in the group between the Permian and Triassic” by Lorenzo Marchetti and Hendrik Klein published in Palaeontology.

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

A remarkable new species of feathered dinosaur has been described from north-eastern China. Named Norellraptor barsboldi, this small theropod is helping scientists understand how flight evolved in the Dinosauria. The research suggests that different groups of feathered dinosaurs developed flight-related adaptations independently, rather than following the same evolutionary pathway.

The international research team, which included Italian palaeontologist Andrea Cau, published its findings in the scientific journal “Nature Communications”.

Say Hello to Norellraptor barsboldi

The fossil was discovered in Lower Cretaceous deposits of the Jiufotang Formation in Liaoning Province, China. The Jiufotang Formation is a member of the extensive Jehol Group. It is famous for its exquisite vertebrate fossils, including dinosaurs, pterosaurs and early birds. Palaeontologists have been able to build up a detailed picture of the environment that existed in this part of the world in the Early Cretaceous. Norellraptor barsboldi belonged to the Microraptorinae, a group of small, feathered theropods closely related to birds. These dinosaurs were members of the Dromaeosauridae, a family that also includes Velociraptor and Deinonychus.

To read an article from 2021 about an incredible flying reptile from the Jiufotang Formation: Remarkable Pterosaur Fossil Helps to Define a Genus.

The almost complete fossil skeleton measures approximately fifty-seven centimetres in length. Furthermore, impressions of some of the animal’s feathers have been preserved.

Figure 1 – Fossil specimen of Norellraptor barsboldi (specimen number 130108-MHGU-F4281). Whole specimen (a) with skull in lateral view (b). Close up of the rostrum (c). Close up view of the posterior part of skull (d). Pectoral region (e) and distal end of the tail (f). Scale bar equals 5 cm (a) and 1 cm (b-f). Picture credit: Wang et al. (2026), Nature Communications. Reproduced with the kind permission of Dr Andrea Cau.

Picture credit: Wang et al. (2026), Nature Communications. Reproduced with the kind permission of Dr Andrea Cau

The researchers also examined the microscopic structure of its bones. Their findings indicate that the dinosaur was at least three years old when it died.

Honouring Two Influential Palaeontologists

The scientific name Norellraptor barsboldi honours two distinguished palaeontologists who made major contributions to dinosaur research. The genus name recognises American palaeontologist Mark Norell (1957–2025), renowned for his research into theropod dinosaurs and the evolutionary origins of birds. Meanwhile, the species name honours Mongolian palaeontologist Rinchen Barsbold (1935–2025). His pioneering research transformed our understanding of theropod anatomy and the close evolutionary relationship between dinosaurs and birds.

Both scientists played important roles in advancing research into feathered dinosaurs.

To read more about the contribution to palaeontology made by Mark Norell: Mark Norell and His Dinosaur Discoveries.

Rinchen Barsbold contributing to research into dromaeosaurids: Natovenator – A Semi-aquatic Dromaeosaurid.

Did Dinosaur Flight Evolve More Than Once?

One of the most intriguing questions in vertebrate palaeontology concerns the evolution of flight. Microraptorines possessed several anatomical features associated with aerial locomotion. For example, some members of this group had long feathers on their forelimbs and hindlimbs. These adaptations suggest that certain microraptorines could move through the air, perhaps by gliding or using other forms of aerial locomotion.

However, scientists have debated whether these adaptations were inherited from a common ancestor shared with birds. Alternatively, similar features might have evolved independently in different dinosaur lineages. The discovery of Norellraptor barsboldi provides important new evidence.

Different Evolutionary Pathways to Flight

The researchers compared anatomical features associated with flight in microraptorines and early birds. Their analysis revealed that approximately thirty percent of the evolutionary innovations identified in microraptorines also appeared independently in the bird lineage.

Crucially, these adaptations did not evolve in the same sequence. This suggests that the two groups developed their flight-related anatomy through different evolutionary pathways.

Evolutionary sequences of the derived features shared by Microraptorinae and Avialae mapped onto the Norellraptor barsboldi holotype. Picture credit: Wang et al. (2026), Nature Communications. Scale bar equals 5 cm. Reproduced with the kind permission of Dr Andrea Cau.

Picture credit: Wang et al. (2026), Nature Communications. Reproduced with the kind permission of Dr Andrea Cau

The researchers also investigated bone growth in microraptorines. Their findings suggest that these dinosaurs may have possessed distinctive patterns of limb development. Taken together, the evidence challenges the idea that birds and microraptorines inherited a common flight apparatus or followed an identical developmental programme. Instead, different evolutionary pressures may have shaped the wings and flight-related anatomy of these closely related dinosaurs.

An Important Discovery for Understanding Bird Evolution

The discovery of Norellraptor barsboldi demonstrates the importance of exceptionally preserved fossils in reconstructing evolutionary history. Although birds evolved from theropod dinosaurs, the development of flight was evidently a complex process.

Different dinosaur lineages experimented with anatomical adaptations that helped them exploit aerial environments. However, these adaptations did not necessarily evolve in the same order or serve identical functions. The new research supports the hypothesis that flight-related adaptations evolved independently in different branches of the dinosaur family tree. Further fossil discoveries and detailed investigations into dinosaur bone growth should help palaeontologists test this evolutionary scenario.

Norellraptor barsboldi provides another fascinating piece of evidence in the continuing investigation into the dinosaur origins of birds.

Everything Dinosaur acknowledges the assistance of corresponding author Dr Andrea Cau (OPHIS Museo Paleontologico e Centro Erpetologico, Teramo, Italy) in the compilation of this article.

The scientific paper: Wang, X., Ji, Y., Cau, A. et al. (2026). “Independent assembly of the flight apparatus in a non-avian dinosaur clade” published in Nature Communications, 17, 10074.

https://doi.org/10.1038/s41467-026-77804-6

The award-winning Everything Dinosaur website: Museum Quality Models of Prehistoric Animals.

Dinosaurs living near the coast may have supplemented their diets with food from the sea. New research suggests that marine resources entered Cretaceous food webs and were consumed by dinosaurs and other vertebrates. Research suggests that some herbivorous dinosaurs ate seaweed.

Scientists examined the chemical composition of fossil teeth and bones. They found evidence that marine-derived nutrients were incorporated into terrestrial food chains. Remarkably, the researchers conclude that some herbivorous dinosaurs may even have eaten seaweed washed ashore. The study provides new insights into the complex ecosystems that existed along the shores of the Western Interior Seaway and the ancient Gulf of Mexico during the Cretaceous.

Dinosaurs and Marine Food Resources

Storms regularly wash seaweed, animals and other organic material onto modern beaches. Terrestrial animals often take advantage of this readily available food. Scientists refer to the movement of nutrients and energy from marine environments into terrestrial ecosystems as marine subsidisation. Indeed, our own species Homo sapiens has a long history of beachcombing.  Early modern humans in South Africa for example, are thought to have survived severe climate change by relying on scouring the shoreline to supplement their diet.

Researchers wanted to discover whether the similar behaviours were exhibited by animals that lived during the Mesozoic.

Dr Clayton W. Forster of the University of Arkansas and colleagues studied the stable carbon isotope composition preserved in fossil material. Their research was published in the journal “Frontiers in Ecology and Evolution Paleoecology”.

The scientists concluded that marine resources probably made an important contribution to several coastal Cretaceous ecosystems.

Dr Forster explained:

“We show that coastal terrestrial organisms in the greenhouse climates of the Cretaceous relied on marine resources to supplement their diets in a similar way that modern organisms do.”

Marine-derived resources could move through the entire food chain. Therefore, an animal did not necessarily have to eat seaweed or other marine material directly to acquire its chemical signature.

Theropod tooth from the Mussentuchit Member assemblage on a foam block next to a scale card. Chemical analysis of fossil teeth can provide evidence about the food consumed by animals millions of years ago. Picture credit: North Carolina Museum of Natural Sciences/Clayton Forster.

Picture credit: North Carolina Museum of Natural Sciences/Clayton Forster

Chemical Fingerprints Preserved in Dinosaur Teeth

The researchers focused particularly on different isotopes of carbon. Carbon occurs naturally in several forms, including carbon-12 and carbon-13. The ratio between these isotopes can provide scientists with information about diet. Importantly, this chemical signal can become incorporated into tooth enamel.

Marine plants tend to have higher carbon isotope values than plants growing on land. Consequently, animals consuming marine vegetation, or eating animals that had exploited marine resources, can acquire a distinctive carbon isotope signature. Scientists had previously encountered unexpectedly high carbon isotope values in Cretaceous vertebrate fossils. The new study offers a possible explanation.

The team analysed fossil material from several formations representing ancient coastal environments. These included the Antlers, Woodbine, Dunvegan and Wayan formations, along with the Mussentuchit Member of the Cedar Mountain Formation. These deposits were associated with the margins of the Western Interior Seaway or the ancient Gulf of Mexico.

For comparison, fossils from the predominantly inland Cloverly Formation were also studied.

The Western Interior Seaway

During parts of the Cretaceous, rising sea levels flooded enormous areas of North America. The Western Interior Seaway eventually divided the continent into western and eastern landmasses (Laramidia and Appalachia). Dinosaurs living close to its shores inhabited environments very different from those of dinosaurs living farther inland. The study examined fossil assemblages dating from the Early to early Late Cretaceous. The researchers identified a consistent difference between coastal and inland ecosystems. Fossils from coastal environments generally possessed higher carbon isotope values. This pattern was detected across different animals and locations. It also occurred at sites of different geological ages.

The scientists interpret this as evidence that marine-derived nutrients were entering terrestrial food webs.

A large crocodilian tooth from the Wayan Formation. The Wayan Formation was one of several deposits included in the study of marine-derived nutrients in Cretaceous ecosystems. The specimen is shown next to a centimetre ruler in a specimen box on top of its specimen information card. Picture credit: Idaho Museum of Natural History/Clayton Forster.

Picture credit: Idaho Museum of Natural History/Clayton Forster

Did Dinosaurs Eat Seaweed?

Perhaps the most intriguing question concerns the source of the marine carbon. Dr Forster and his colleagues suggest that marine macroalgae and aquatic plants are strong candidates. The chemical signature occurred in animals occupying different parts of the food web. Therefore, the original source was probably situated relatively low down in the ecosystem.

Seaweed fits this hypothesis extremely well.

Large herbivorous mammals living near coastlines today sometimes eat seaweed. It provides a useful supplementary food source, particularly when terrestrial vegetation becomes scarce.

The researchers propose that coastal herbivorous dinosaurs may have behaved in a similar way.

Dr Forster added:

“Few organisms meet these criteria besides marine macroalgae or macrophytes – seaweeds.”

If herbivorous dinosaurs consumed washed-up seaweed, the marine-derived carbon could subsequently have passed to predatory dinosaurs when they ate these herbivores. Therefore, the research does not necessarily imply that theropod dinosaurs regularly hunted marine animals. Instead, marine nutrients could have moved through a complicated network of ecological relationships.

Not Every Dinosaur Ate Marine-derived Food

Intriguingly, the researchers also discovered evidence of dietary selectivity. Tenontosaurus tilletti was a large herbivorous dinosaur known from several Lower Cretaceous formations of North America. The carbon isotope values associated with the Tenontosaurus material examined were consistent with animals feeding primarily on terrestrial vegetation. The researchers concluded that T. tilletti apparently preferred non-marine food resources, although relatively few specimens were available for analysis.

Tenontosaurus tilletti illustration. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

This is an important observation. It suggests that the unusual chemical signatures were associated with diet rather than simply being the result of geological processes altering the fossils after burial.

A Tenontosaurus tilletti tooth from the Cloverly Formation assemblage in a glass sample vial. This ornithopod appears to have preferred terrestrial vegetation rather than marine-derived food. Picture credit: Sam Noble Oklahoma Museum of Natural History/Clayton Forster.

Picture credit: Sam Noble Oklahoma Museum of Natural History/Clayton Forster

Analysing a Cretaceous Food Web

The Cloverly Formation fossils provided an important comparison with the coastal assemblages. The study included teeth from dinosaurs and crocodilians as well as material from other vertebrates. Some specimens were destructively sampled so that their isotopic composition could be determined.

The results indicate that the predominantly inland Cloverly ecosystem lacked the widespread marine influence identified in the coastal deposits.

However, the picture was not entirely straightforward. One gar specimen from the Cloverly Formation preserved chemical evidence suggesting a connection with a marine or estuarine environment. This hints at just how complex interactions between freshwater, marine and terrestrial ecosystems could have been.

Five fossil teeth specimens from the Cloverly Formation assemblage after destructive sampling for isotopic composition and laser ablation analysis. The specimens from left to right are three specimens of crocodilian teeth, the fourth tooth is a Deinonychus antirrhopus tooth, and, finally, on the far right is a Sauropelta edwardsi tooth. The specimens are mounted on adhesive putty attached to a glass slide with specimen labels below them. Picture credit: Sam Noble Oklahoma Museum of Natural History/Clayton Forster.

Picture credit: Sam Noble Oklahoma Museum of Natural History/Clayton Forster

Reconstructing Ancient Dinosaur Dominated Ecosystems

The research demonstrates that palaeontologists need to consider connections between terrestrial and marine habitats when reconstructing ancient ecosystems. Coastlines are dynamic, ever-changing environments. Nutrients move between land and sea, storms deposit organic material on beaches and animals exploit whatever food resources become available.

The same processes appear to have been operating millions of years ago. Furthermore, marine resources might have become especially important during periods when terrestrial food was scarce. Modern coastal ecosystems demonstrate how marine-derived nutrients can help support terrestrial communities.

The researchers conclude that marine macroalgae and other marine plants may have represented important alternative food resources for coastal dinosaurs. This could also help palaeontologists interpret unusual carbon isotope values identified in other Cretaceous fossils.

The First Study of Marine Subsidisation in Mesozoic Terrestrial Ecosystems

The study represents the first identification of marine subsidisation in prehistoric terrestrial ecosystems. Further research could establish how widespread the phenomenon was at other latitudes and during different intervals of geological time.

Dr Forster summarised the wider significance of the research:

“Our study emphasises the connections between terrestrial and marine ecosystems.”

Dinosaurs are often reconstructed as inhabitants of forests, floodplains and river systems. However, this study provides a reminder that many species also lived close to enormous inland seas. Some of these dinosaurs may have wandered along Cretaceous shorelines exploiting whatever the tides and storms brought onto the beach. Intriguingly, studies of trackways found in Jurassic-aged sediments on the Scottish island of Skye indicate the presence of sauropods in coastal environments.  It had been suggested that the relatively open beach environments acted as migration routes for these large herbivores. After all, moving along the coast would have been easier than moving through a dense forest landscape. However, these habitats with their abundant seaweeds being washed up with the tide could have provided plant-eating dinosaurs with a substantial food resource.

To read more about the remarkable sauropod trace fossils on the Isle of Skye: Isle of Skye Sauropods and their Watery World.

For herbivorous dinosaurs at least, that could sometimes have meant adding a little seaweed to the menu.

The scientific paper: “Marine subsidization of dinosaurian ecosystems” by Clayton W. Forster, Celina A. Suarez, Thomas M. Cullen, Lindsay E. Zanno and Ethan G. Hyland published in Frontiers in Ecology and Evolution Paleoecology.

Link: The Scientific Paper.

A new species of large tyrannosaur has been named and described from fossils found in Alberta (Canada). The new theropod, Tromerosaurus solumons, lived around 76 million years ago (Campanian faunal stage of the Late Cretaceous). Intriguingly, this predator possessed a mixture of anatomical characteristics associated with two major tyrannosaurid lineages.

The study could change our understanding of tyrannosaur evolution. It suggests that important tyrannosaurid lineages may have diverged later and evolved more rapidly than previously thought. Mark J. Powers of the University of Alberta, lead author of the paper, assisted Everything Dinosaur in the compilation of this article by providing images.  The study has been published in the “Journal of Vertebrate Paleontology”.

Tromerosaurus attacks a pair of juvenile Brachylophosaurus. Picture credit: Henry Sharpe.

Picture credit: Henry Sharpe

Introducing Tromerosaurus solumons

In 2010, a partial tyrannosaur skeleton was discovered in exposures associated with the upper Oldman Formation of Alberta. The University of Alberta mounted two expeditions (2010 and 2011 field seasons) to recover the skeleton.  A substantial part of the skull, vertebrae, both humeri along with hind limb material and parts of the pelvis were recovered. The skull was prepared at the University of Alberta Laboratory for Vertebrate Palaeontology.

The skull of the holotype specimen (UALVP 52981). Picture credit: Khoi Nguyen.

Picture credit: Khoi Nguyen

A Tyrannosaur with Unique Anatomical Traits

The anatomy of Tromerosaurus proved particularly interesting. Tyrannosaurids are traditionally divided into two important branches: Albertosaurinae and Tyrannosaurinae. Albertosaurines include Albertosaurus and Gorgosaurus. Tyrannosaurines include apex predators such as Daspletosaurus, Tarbosaurus and Tyrannosaurus. However, Tromerosaurus does not fit comfortably into this simple division.

Its anatomy combines characteristics seen in Gorgosaurus with features associated with Daspletosaurus. The research team found particularly important differences in the maxilla, the large tooth-bearing bone forming much of the side of the upper jaw. In addition, morphometric analysis revealed an intermediate morphology. For example, Tromerosaurus has a proportionally longer maxillary fenestra and a narrower pila promaxillaris (the strut of bone that separates the promaxillary fenestra from the maxillary fenestra in the skull), than Gorgosaurus libratus.

This unusual mixture of anatomical features makes the new taxon important for understanding early tyrannosaurid evolution.  It also suggests a greater diversity of tyrannosaur species in North America during the Late Cretaceous than previously thought.

Tromerosaurus solumons humeri (upper arm bones). Picture credit: Mark Powers (University of Alberta).

Picture credit: Mark Powers (University of Alberta)

Fossils Previously Assigned to the Gorgosaurus Genus

The researchers did not restrict their study to the holotype specimen.  Instead, they conducted an extensive examination of other tyrannosaur fossils.  It was discovered that some specimens previously assigned to the Gorgosaurus genus could instead by referred to T. solumons. Among the reassigned fossils is the substantial specimen TMP 1994.012.0602 and another individual, TMP 1995.005.0001. Additional isolated maxillary material has also been referred to the new tyrannosaur taxon.

Consequently, palaeontologists have fossils representing animals of different sizes and growth stages. This provides considerably more anatomical information than would be available from the holotype alone.

Skeletal reconstruction of Tromerosaurus solumons (A), size estimates vary but when fully grown this dinosaur could have had a body length of between 7 and 9 metres. Referred specimens and the skeletal components (B). Picture credit: Figure 4 in Powers et al 2026..

Picture credit: Figure 4 in Powers et al 2026

Tromerosaurus, Gorgosaurus and the Fossil Record

The stratigraphic distribution of these fossils provides another important piece of evidence. Tromerosaurus and Gorgosaurus appear to have had a restricted period of stratigraphic overlap. This supports the researchers’ interpretation that they represent distinct taxa rather than merely different growth stages or successive forms of the same tyrannosaur lineage. This has wider implications. For example, large tyrannosaurids have sometimes been regarded as comparatively long-lived species with relatively low taxonomic diversity. In contrast, the herbivorous dinosaurs living alongside them appear extremely diverse.

For instance, researchers have identified numerous species of ceratopsian in North America.  Many of these species were coeval. High endemism within centrosaurines was demonstrated with the discovery of Lokiceratops (L. rangiformis) from the Judith River Formation of Montana.

To read more about the discovery of Lokiceratops: A New Horned Dinosaur from Montana.

A new lambeosaurine hadrosaur from the Oldman Formation: A Newly Described Lambeosaurine Dinosaur.

The discovery of Tromerosaurus adds evidence suggesting that tyrannosaur diversity may have been underestimated.

The pelvis of the holotype specimen (UALVP 52981). Picture credit: Mark Powers (University of Alberta).

Picture credit: Mark Powers (University of Alberta)

Finding a Place for Tromerosaurus in the Tyrannosaur Family Tree

Perhaps the most fascinating part of the study concerns the dinosaur’s evolutionary relationships. The researchers tested the phylogenetic position of Tromerosaurus using different analytical methods. Remarkably, they obtained different results. A parsimony analysis placed Tromerosaurus as the earliest-diverging member of the Albertosaurinae. However, a Bayesian analysis recovered it within the Tyrannosaurinae sub-family. This discrepancy is scientifically important.

Tromerosaurus possesses a mosaic of characteristics associated with both sub-families. Its anatomy could therefore record a period when the distinctive features of albertosaurines and tyrannosaurines were becoming established. The researchers propose that the divergence of these two major tyrannosaurid lineages could have occurred later than previously thought. Furthermore, anatomical characteristics may have been acquired remarkably rapidly as tyrannosaurids diversified during the Late Cretaceous.

What’s In a Name?

The etymology of this new taxon is fascinating. The genus name combines the Greek “tromeros”, meaning frightening, terrible or alarming, with “sauros”, meaning lizard. The choice also echoes the names Daspletosaurus (“frightful lizard”) and Gorgosaurus (“dreadful/terrible lizard”), reflecting the animal’s intriguing combination of Albertosaurinae and Tyrannosaurinae anatomical characteristics.

The species name combines the Latin terms for “lonely mountain”.  It relates to the isolated nature of the lacrimal horn associated with the skull.  There is also a deliberate literary connection. The name references the Lonely Mountain, home of the dragon Smaug in J. R. R. Tolkien’s famous book entitled “The Hobbit”.

Tromerosaurus solumons – Leads to a Re-examination of Tyrannosaur Evolution

The scientific description of Tromerosaurus solumons demonstrates how museum specimens can transform our understanding of theropod dinosaur evolution. Some fossils referred to the new taxon had previously been interpreted as belonging to other tyrannosaurids. Detailed anatomical comparisons and improved information about their geological positions allowed researchers to recognise a previously unknown predator. Furthermore, Tromerosaurus suggests tyrannosaur evolution was perhaps more dynamic than traditionally envisaged.

Rather than consisting of a few long-lived species gradually replacing one another, Late Cretaceous tyrannosaurids may have undergone periods of relatively rapid diversification. Their evolutionary history could have been every bit as complex as that of the horned dinosaurs and duck-billed dinosaurs upon which they preyed.

Mike from Everything Dinosaur commented:

“Tromerosaurus solumons is a fascinating addition to the Tyrannosauridae family. It demonstrates how difficult it can be to unravel the evolutionary relationships of these theropods. The mixture of anatomical characteristics associated with different tyrannosaurid lineages makes this new taxon particularly significant.  Moreover, the study also highlights the importance of revisiting previously collected fossils. Specimens originally assigned to familiar genera such as Gorgosaurus can provide fresh information when examined in the light of new discoveries.”

A new tyrannosaur from the Foremost Formation of Alberta: Canada’s Oldest Tyrannosaur.

Everything Dinosaur acknowledges the assistance of PhD student Mark Powers and the University of Alberta in the compilation of this article.

The scientific paper: “A new albertosaurine from the Oldman Formation, Alberta, Canada, illuminates ambiguity between albertosaurine and tyrannosaurine characteristics” by Mark J. Power, James G. Napoli, Colton C. Coppock, Henry S. Sharpe, Christiana W. Garros, Alexandre V. Demers-Potvin, Gorm S. Raun, Jordan C. Stock, Tetsuto Miyashita and Philip J. Currie published in the Journal of Vertebrate Paleontology.

Scientists have described a new species of dicynodont from fossils discovered in Tanzania. These fossils could help palaeontologists refine the timeline for the origin of the dinosaurs. The new species has been named Dinodontosaurus isiyavamanda. It lived around 240 million years ago during the Triassic Period. Importantly, Dinodontosaurus was not a dinosaur. As a dicynodont, it is a synapsid, an evolutionary lineage that eventually produced modern mammals.

An international research team led by the University of Bristol described the new species. Their study has been published in the Journal of Vertebrate Paleontology.

Introducing Dinodontosaurus isiyavamanda

Researchers examined an associated dicynodont skeleton collected during a British expedition to Tanzania in 1963. The fossils subsequently entered the collection of the Natural History Museum in London. However, much of this material remained only partly studied. The scientists combined their examination of the historic specimen with a more recently discovered fragmentary skull. Their analysis identified the fossils as belonging to the genus Dinodontosaurus.

This identification came as a surprise. Previously, Dinodontosaurus fossils had only been confirmed from South America. Furthermore, detailed anatomical comparisons demonstrated that the Tanzanian fossils represented a new species.

Dinodontosaurus isiyavamanda life reconstruction. Picture credit: Gabriel Ugueto.

Picture credit: Gabriel Ugueto

The species name “isiyavamanda” refers to the land of the Wamanda people. They inhabit the region of Tanzania where the fossils were discovered.

Hady George, a PhD student at the University of Bristol and lead author of the study, explained:

“Our discovery marks the first confirmed record of the genus Dinodontosaurus outside South America. The finding links the Tanzanian and South American fossil-bearing rocks, showing they are of equivalent age.”

A related article: The Oldest Dinosauromorph from South America.

A new silesaurid from the Dinodontosaurus Assemblage Zone: Gondwanax – A New Silesaurid Taxon.

An Important Triassic Herbivore

Dicynodonts were extremely successful synapsids. They first evolved during the Permian and survived the devastating end-Permian mass extinction. These generally stocky animals subsequently became important components of many Triassic terrestrial ecosystems. The last dicynodonts lived during the Late Triassic around 205 million years ago.  For example, the giant Lisowicia (L. bojani), roamed what is now known as Poland during the Rhaetian age of the Late Triassic. Lisowicia is the largest known dicynodont, as well as the largest non-mammalian synapsid.

A scale drawing of the giant dicynodont Lisowicia bojani. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The researchers identified several anatomical characteristics that distinguish Dinodontosaurus isiyavamanda from the South American species. For example, the new species possessed a distinctive structure to its palate. The researchers suggest this feature could relate to food processing. In addition, this autapomorphy hints at niche partitioning. Perhaps D. isiyavamanda exploited different food resources compared to other coeval dicynodonts. Such resource partitioning could have helped several large herbivores coexist.

Rethinking the Timeline of Dinosaur Origins

The Tanzanian fossils come from the famous Manda Beds. These rocks have yielded an extraordinary assemblage of Middle to Late Triassic vertebrates. Crucially, the Manda Beds have also produced fossils linked to the earliest stages of dinosaur evolution. These include Nyasasaurus, a possible early dinosaur, and the dinosauriform Asilisaurus.

Everything Dinosaur’s 2012 article highlighting the discovery of Nyasasaurus parringtoni: Pushing Back the Date of Dinosaur Evolution.

An article from 2010 examining fossil evidence from Tanzania that sheds light on the evolution of the Dinosauria: Dinosauria Evolved Ten Million Years Earlier.

Determining the age of these rocks is therefore extremely important. Previously, scientists correlated parts of the Manda Beds with fossil-bearing deposits in South Africa. This correlation supported an older Middle Triassic age for some of the Tanzanian fossils.

However, the identification of Dinodontosaurus in Tanzania provides another way to correlate these rocks. Dinodontosaurus is also known from South America. Therefore, its presence provides a biostratigraphic link between fossil deposits separated today by the Atlantic Ocean.

Dinodontosaurus isiyavamanda front of the skull and the lower jaw. Picture credit: Jonathan Jackson and Hady George.

Picture credit: Jonathan Jackson and Hady George

Dating the Manda Beds

Around 240 million years ago, Africa and South America formed parts of the enormous supercontinent Pangaea. Consequently, animals could disperse across regions that are now widely separated. Recent radiometric dating of South American rocks indicates that these deposits are younger than the South African rocks used in earlier correlations. The difference could be as much as ten million years.

The new study therefore supports a late Ladinian to Carnian age for the relevant Manda Beds. This has important consequences for interpreting the earliest dinosaur fossils.

Hady George commented:

“This helps confirm that the oldest dinosaur candidates from Tanzania are probably no older than those from South America, refining the timeline of dinosaur origins.”

Rather than demonstrating that dinosaurs had already evolved substantially earlier in Africa, the Tanzanian fossils may be broadly contemporary with early dinosaur evidence from South America.

A Fossil Waiting More Than Sixty Years

The research also demonstrates the enormous scientific importance of museum collections. Some of the material used to describe Dinodontosaurus isiyavamanda has been cared for by the Natural History Museum for more than six decades. Indeed, palaeontologist Nigel Larkin first studied the dicynodont skeleton during his MSc at University College London in 1994. At the time, he concluded that it probably represented a species new to science.

However, almost three decades passed before work began to formally describe it.

Nigel Larkin stated:

“Techniques have improved vastly over the last 30 years too – we can do so much more with Micro CT scanning etc to examine such specimens than we ever could have imagined in the 1990s, and international collaboration is so much easier.”

Modern scanning technology allows palaeontologists to examine fossil anatomy in extraordinary detail. Furthermore, researchers can study internal structures without damaging precious specimens.

Dr Mike Day, Curator of Non-Mammalian Tetrapods at the Natural History Museum, highlighted the importance of historic collections.

He added:

“It goes to show how revisiting museum collections can change our understanding of the past just as much as finding new fossils in the field.”

More Dinodontosaurus Fossils to Study

The story of Dinodontosaurus isiyavamanda is far from complete. A substantial amount of Tanzanian material still awaits detailed examination. In particular, researchers intend to investigate more of the postcranial skeleton. The scientists plan to compare these bones with Dinodontosaurus fossils from South America. In addition, they hope to investigate the biomechanics of these remarkable herbivores.

This research could reveal how several large dicynodont species shared the same environments and food resources.

More than sixty years after its discovery, an overlooked museum specimen has acquired a unique scientific identity. Moreover, it is helping palaeontologists piece together events near the dawn of the Dinosauria. The description of Dinodontosaurus isiyavamanda demonstrates that old fossils can still produce new surprises. In this case, they could even help change our understanding of when the first dinosaurs evolved.

Everything Dinosaur acknowledges the assistance of the University of Bristol in the compilation of this article.

The scientific paper: “Craniomandibular osteology of Dinodontosaurus isiyavamanda sp. nov. (Therapsida: Anomodontia) from the Manda Beds of Tanzania and new support for a younger age for the alleged oldest dinosaurs” by Hady George, Juan A. Escobar, Edmund R.R. Moody, Charles B. Saanane, Michael O. Day and Nigel R. Larkin published in the Journal of Vertebrate Paleontology.

For museum quality replicas of dicynodonts and other prehistoric creatures: Models of Prehistoric Creatures.

A huge international study has shed new light on bat evolution. The research suggests that bats originated in Europe around 65 million years ago. Moreover, both powered flight and echolocation appear to have evolved very early in their history.

The study represents the largest investigation yet to combine bat genomes with evidence from the fossil record. An international team of 137 researchers from 64 countries took part. Scientists from the Museum für Naturkunde Berlin also contributed to the research.

The findings have been published in the journal Nature.

Combining Bat Fossils with Genetic Evidence

Researchers analysed high-quality genomes representing 103 bat species. Significantly, these species represent all 21 currently recognised bat families. The scientists also incorporated 44 fossil bats from different parts of the world.

By combining these two sources of evidence, the team reconstructed the evolutionary history of bats. Their analysis also helped resolve several long-standing questions about relationships between the major bat groups. Previous studies proposed that bats originated in Asia, Africa or North America. However, the new research points towards Europe as their place of origin.

The first bats probably appeared around 65 million years ago. This date places their origins close to the beginning of the Cenozoic Era.

Early bats subsequently spread from Europe into Africa. Therefore, the researchers propose a European-African area from which bats later dispersed farther afield. Eventually, they reached Asia, the Americas and Australia.

A variety of extant bat species surrounding a photograph of Palaeochiropteryx tupaiodon known from the Middle Eocene of Europe. Fossils of this species are associated with the remarkable Messel Shale site in Germany. Picture credit: BAT1K

Picture credit: BAT1K

Individual image credits:

Bat species, from top left to bottom right: Macrotus waterhousi © Charles Francis; Glossophaga mutica © Brock and Sherri Fenton; Molossus nigricans © Brock and Sherri Fenton; Uroderma convexum © Elizabeth Clare; Cynopterus sphinx © Charles Francis; Palaeochiropteryx tupaiodon [fossil] © Matthew Jones; Pipistrellus nathusii © Jens Rydell; Tadarida brasiliensis © Elizabeth Clare; Rhinolophus trifoliatus © Charles Francis; Desmodus rotundus © Charles Francis; Vespertilio murinus © Jens Rydell.

Echolocation Evolved Early

The study also provides important evidence about the origins of echolocation. Researchers examined the position of the fossil bat Vielasia on the bat family tree. Its placement within one of the oldest branches suggests that echolocation evolved extremely early.

Indeed, echolocation probably appeared before the major modern bat lineages diverged. Powered flight also developed very early in bat evolution. Consequently, the two characteristics most closely associated with bats were present near the beginning of their evolutionary history.

These remarkable adaptations may help explain their subsequent success.

Today, more than 1,500 bat species are known. They account for approximately one-fifth of all living mammal species. Furthermore, bats have colonised environments across much of the world.

The Remarkable Success of Bats

Bats are the only mammals capable of powered flight. Many species can also navigate and hunt in complete darkness using echolocation. However, their remarkable biology extends far beyond flight and sophisticated senses. Bats perform important ecological roles. For example, some species pollinate plants or disperse seeds. Others consume huge numbers of insects, including agricultural pests.

In addition, many bats show unusual resistance to disease. They can also live exceptionally long lives relative to their body size. The new genomic dataset could help scientists investigate the biological mechanisms responsible for these traits.

The atmospheric Messel gallery at the Senckenberg Museum (Frankfurt). Fossil bat specimens examined in this study are associated with the remarkable Messel Shales. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Reconstructing the Ancestral Bat Genome

As part of the project, researchers reconstructed the genome of the common ancestor of living bats. This achievement gives scientists a powerful new research resource. They can now investigate genetic changes associated with the extraordinary diversification of bats. Researchers can study changes affecting individual DNA building blocks. They can also examine much larger sections of genetic material. As a result, scientists hope to identify genetic changes linked to flight, echolocation, longevity and disease resistance.

Such research could eventually have implications beyond the study of bats. In particular, understanding their longevity and immune systems might contribute to research into human ageing and disease.

A New Framework for Studying Bat Evolution

The research was undertaken as part of the international Bat1K consortium. This initiative aims to produce and analyse high-quality reference genomes for all living bat species. For decades, scientists have debated fundamental questions concerning the origins of bats. The relationships between different bat families have also proved difficult to resolve. By bringing fossils and genomic evidence together, this enormous study provides a new evolutionary framework.

It suggests that the story of bats began in Europe approximately 65 million years ago. Soon afterwards, these pioneering mammals possessed two extraordinary adaptations – powered flight and echolocation. These abilities would ultimately help bats become one of the most diverse and successful groups of mammals on Earth.

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

The scientific paper: “Reference genomes and fossils revise bat family phylogeny and biogeography” by Morales, A.E., Liang, Y., Thomas, W.R. et al published in the journal Nature.

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

Recently, Everything Dinosaur published an article about the discovery of some remarkable, probable Tyrannosaurus rex tracks that had been discovered in North Dakota. The three-toed prints were made by a large theropod. The trackway measures around seven metres in length and four individual prints have been excavated. There are probably more but the overburden from the hill would be difficult to remove to expose the entire trackway. The four prints that have been found represent two left prints and two right prints – a walking sequence.

The size and tridactyl nature of the tracks is consistent with an adult Tyrannosaurus rex trackmaker. Researchers from the Denver Museum of Nature & Science and Liverpool John Moores University studied the trackway. Their research has been published in the Journal of Vertebrate Paleontology.

To read Everything Dinosaur’s earlier article about this trace fossil discovery: Extraordinary Probable Tyrannosaurus Trackway Discovered.

How Did These Trace Fossils Form?

Trace fossils such as these footprints preserve evidence of the activity of an animal. In contrast to body fossils such as teeth or bones which can be transported a long way from where the animal died, most trace fossils are direct evidence of the environment at the time and the place where the animal lived. Trace fossils often provide in situ evidence.

Intriguingly, the tracks are preserved as raised mounds (epirelief).  How did they form?  Thankfully, the media release from the Denver Museum of Nature & Science also included some beautiful artwork by Andrey Atuchin that illustrate their formation.

In order to have potential Tyrannosaurus rex tracks preserved, the first thing required is to have a dinosaur (a T. rex) leave its footprints in a substrate such as soft mud.

The large theropod (probable Tyrannosaurus rex) walks along leaving tracks in soft mud. Picture credit: Andrey Atuchin.

Picture credit: Andrey Atuchin

The mud dries out and the impression of dinosaur’s foot is preserved as a tridactyl depression in the mud.

Over time the mud hardens leaving a track preserved in the mud. Picture credit: Andrey Atuchin.

Picture credit: Andrey Atuchin

The Track is Filled by Sediment

The indentation caused by the dinosaur’s foot is gradually filled in with other sediment. In this case, sand slowly fills the track. This forms a natural cast of the print.

The track is gradually infilled by sediment such as sand, creating a natural cast of the footprint. Picture credit: Andrey Atuchin.

Picture credit: Andrey Atuchin

Over millions of years the sand turns into sandstone and the mud forms mudstone.  These two different types of sedimentary rock might erode at different rates. For example, the softer mudstone erodes quicker than the sandstone.  Thus, a track is preserved as a raised structure (epirelief).

The hard sandstone is more resistant to weathering and over time the track is left as a raised portion of rock (epirelief) surrounded by more rapidly eroded mudstone. Picture credit: Andrey Atuchin.

Picture credit: Andrey Atuchin

Three of the footprints are expected to be recovered by helicopter this autumn (2026) and then transported to the Denver Museum of Nature & Science. We wish the research team every success with their endeavours to recover and preserve these amazing tracks.

Everything Dinosaur acknowledges the assistance of a media release from the Denver Museum of Nature & Science in the compilation of this article.

The scientific paper: “A large tridactyl trackway from the Upper Cretaceous Hell Creek Formation of North Dakota, likely attributable to an adult Tyrannosaurus rex” by Peter L. Falkingham, Kent M. Hups, Evan M. Tamez-Galvan, Antoine D. Bercovici and Tyler R. Lyson published in the Journal of Vertebrate Paleontology.

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