Scientists studying the famous Oxfordshire “dinosaur highway” have announced that one of the giant trackways may represent the longest known sauropod trackway discovered anywhere in the world. The remarkable sequence of footprints, uncovered at Dewars Farm Quarry, could have been made by a single Cetiosaurus as it wandered across a Jurassic mudflat around 166 million years ago.

The Dewars Farm Quarry excavation work taking place in June 2024. Picture credit: The University of Birmingham.

Picture credit: The University of Birmingham

A Giant Dinosaur Left Its Footprints

Researchers have traced the trackway for approximately two-hundred and twenty metres. This enormous trail records the movements of a huge, long-necked herbivore. Furthermore, scientists think the tracks were made by a Cetiosaurus or a sauropod similar to Cetiosaurus, the first sauropod to be scientifically described (Owen, 1841). In total, four sauropod trackways at the site have been discovered. In addition, the site has yielded several other trackways, including those of a meat-eating dinosaur.  These tracks have been tentatively assigned to Megalosaurus.

The original discovery attracted worldwide attention when details were formally announced in early 2025. The sauropod tracks represent animals of different sizes.  This suggests some intriguing possibilities.  For example, the tracks could represent a family moving together, or the trackways could represent a group of unrelated animals moving together.  In an interview with Radio Oxfordshire, co-leader of the excavation Dr Emma Nichols (Oxford University Museum of Natural History), opined that the trace fossils could represent more than one type of sauropod.

Working on the Dewars Farm Quarry dinosaur tracks. Picture credit: Caroline Wood University of Oxford.

Picture credit: Caroline Wood University of Oxford

The Oxfordshire “Dinosaur Highway” Made by a Cetiosaurus (Possibly)

The tracks cannot be linked directly to a skeleton. However, the footprints closely resemble those expected from a large, narrow-gauge sauropod. Consequently, scientists have suggested that the trackmaker was probably Cetiosaurus.

Cetiosaurus lived during the Middle Jurassic. It reached lengths of around eighteen metres and weighed many tonnes. Moreover, the type species, Cetiosaurus oxoniensis, was named from fossils discovered in Oxfordshire. Therefore, assigning the tracks to this dinosaur makes geological sense.

Fossils ascribed to the taxon Cetiosaurus on display at the Oxford University Museum of Natural History (OUMNH). Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

To read Everything Dinosaur’s article from January 2025 (formal announcement of quarry discovery): Remarkable Dinosaur Highway Uncovered in Oxfordshire.

Following in the Footsteps of Jurassic Giants

Trackways provide a different type of evidence from fossil bones. Skeletons reveal anatomy. However, footprints capture behaviour. They show how dinosaurs moved and interacted with their environment. Using modern imaging techniques, researchers have created detailed three-dimensional models of the trackway. As a result, scientists can estimate walking speed and study the animal’s gait. The Oxfordshire trackways represent one of the most important dinosaur discoveries made in Britain for decades. Furthermore, they provide a rare snapshot of life during the Middle Jurassic.

An illustration of a typical sauropod from the Middle Jurassic (Cetiosaurus). It is thought that the Oxfordshire “dinosaur highway” was created by Cetiosaurus or sauropods similar to Cetiosaurus. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

One of the World’s Most Important Dinosaur Sites

At the time the tracks were made, much of Britain was covered by a shallow sea. The Oxfordshire area formed part of a shallow tropical landscape. Mudflats and lagoons provided ideal conditions for preserving footprints. Consequently, the tracks survived for millions of years beneath layers of sediment.

Scientists continue to investigate the quarry. Therefore, further discoveries may yet emerge from this extraordinary site.  However, it is not the only site where long trackways of sauropod dinosaurs have been discovered.

Commenting on the on-going research, Mike from Everything Dinosaur stated:

“The Dewars Farm Quarry site is remarkable. Scientists think there are more footprints awaiting discovery. Hopefully, the site’s owners will continue to work closely with the researchers as well as Natural England to ensure that these fossils are preserved.”

Everything Dinosaur acknowledges the assistance of a media release from the University of Birmingham supplied in January 2025 in the compilation of this article.

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

Researchers have described a single dinosaur caudal vertebra (tail bone) from Denman Island (British Columbia, Canada).  It has been identified as an ornithomimosaur caudal vertebra. The fossil, thought to represent a bone from the middle part of the tail, is only the second dinosaur fossil identified from the Upper Cretaceous Nanaimo Group. In addition, it is the first definitive dinosaur fossil found in Canadian outcrops. Specifically, the caudal vertebra is from marine sediments of the Campanian-aged Cedar District Formation. The fossil discovery suggests that ostrich-like dinosaurs were present on the western margins of Laramidia.

A single dinosaur caudal vertebra similar to the fossil discovery. A tail bone ascribed to the Ornithomimosauria clade has been found in Upper Cretaceous deposits on Denman Island (British Columbia). Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

A Dinosaur Caudal Vertebra

The discovery of the single caudal bone is only the second reported occurrence of dinosaur fossils from the Upper Cretaceous Nanaimo Group. In 2015, we reported a partial theropod femur from Sucia Island (Washington State, USA). Interestingly, this bone also derives from the Cedar District Formation, but it is geologically older than the ornithomimosaur tail bone.

• Partial theropod femur (Washington State, USA) – 83.6 to 79.8 mya
• Mid-caudal ornithomimosaur vertebra (Denman Island, British Columbia, Canada) – 79.8 to 75.5 mya

mya = millions of years ago.

To read our blog post from 2015 about the partial theropod femur fossil discovery: Washington State’s First Dinosaur.

The Upper Cretaceous Nanaimo Group

The deposits of the Upper Cretaceous Nanaimo Group of Vancouver Island have been studied for decades. Numerous vertebrate fossils have been collected representing a diverse marine biota. For example, fossils of fish including sharks, pterosaurs, elasmosaurids and birds have been found. However, despite intensive collecting no dinosaur fossils had been discovered.

Writing in the journal “FACETS” researchers, Victoria Arbour (Royal British Columbian Museum), Timon Bullard (École Secondaire Esquimalt High School) and David Evans (Royal Ontario Museum) describe an isolated theropod caudal vertebra. The fossil was found in marine sediments of the Campanian-aged Cedar District Formation of Denman Island. This small island is located off the eastern coast of the much larger Vancouver Island.

Contemporaneous with Judith River and Two Medicine Formation Biotas

The bone resembles the tail bones of ornithomimosaurs. However, the specimen cannot be identified at the family level. It was likely transported from the western margin of North America to the east. The Nanaimo Group was deposited at least 37o miles (600 km) south of its present position, and this ornithomimosaur likely lived at a similar palaeolatitude to contemporaneous dinosaur faunas in the Two Medicine and Judith River formations in the Western Interior.

Ornithomimosaurs were probably feathered.  In addition, they had long necks, small skulls and lengthy tails. Analysis of the long and graceful hindlimbs suggests that these dinosaurs were fast runners. The caudal vertebra found on Denman Island is likely to have come from the middle part of the animal’s tail.

The image (above) is that of the recently introduced CollectA Deluxe Gallimimus model.  It is a popular figure with collectors and dinosaur fans.  Furthermore, it is one of very few models representing ornithomimosaurs available.

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

The scientific paper: “An ornithomimosaur from the Campanian Cedar District Formation (Nanaimo Group) of Denman Island, British Columbia, Canada” by Victoria M. Arbour, Timon S. Bullard and David C. Evans published in FACETS.

For models of ornithomimosaurs and other dinosaurs: Theropod Models and Dinosaur Toys.

Palaeontologists have described a new species of microraptorine theropod from north-western China. Named Jian changmaensis, this small, feathered dinosaur probably glided on four wings. The fossil provides fresh insights into Early Cretaceous ecosystems and extends the known range of the Microraptorinae. The fossil material consists of an articulated partial left pectoral girdle and forelimb. It consists of a complete scapulocoracoid, humerus, radius, and ulna. The specimen number is GSGM-D050.

The fossil comes from the Lower Cretaceous Xiagou Formation of the Changma Basin (Gansu Province). These lake deposits date to the Aptian faunal stage. Researchers have collected more than one hundred bird fossils from this site. However, no non-avian dinosaur body fossils had been described until now. Jian is the first non-avian dinosaur body fossil from the Xiagou Formation of the Changma Basin.

Jian changmaensis life reconstruction. The new microraptorine theropod Jian changmaensis (left) attacks the early bird Gansus yumenensis (right) in what is now the Changma Basin of north-western China approximately 120 million years ago. Picture credit: illustration by Lewis LaRosa, colourised by Jão Canol.

Picture credit: Lewis LaRosa, colourised by Jão Canol

Jian changmaensis from the Xiagou Formation

The location is famous for the relative abundance of aquatic bird fossils. This assemblage is dominated by fossils of the pigeon-sized Gansus yumenensis. Classified as an ornithuran, G. yumenensis is thought to be a closely related to the ancestors of modern birds. Many of the specimens preserved in the fine-grained mudstones show soft tissue structures like feathers and webbing between their toes. This prehistoric bird was probably volant and capable of diving.

Scientists Suspected the Presence of a Predator

Intriguingly, palaeontologists had found examples of crushed bird bones and evidence of regurgitated remains, interpreted as undigestible pellets coughed up by a predator. Scientists speculated that a larger predatory animal must have hunted these ancient birds. However, direct fossil evidence proved elusive. Although far from complete, the limb bones preserve enough anatomical information to identify a new genus and species within the Dromaeosauridae family.  Specifically, phylogenetic analysis places Jian changmaensis within the Microraptorinae subfamily. This group contains small dromaeosaurids closely related to Microraptor. Members of this clade are famous for their feathered limbs and possible gliding abilities.

Holotype of Jian changmaensis, (GSGM-D050), an articulated partial left pectoral girdle (scapulocoracoid) and forelimb (humerus, radius, and ulna). Silhouette of generalised microraptorine dromaeosaurid theropod (courtesy Scott Hartman) showing skeletal elements preserved (A). Photograph of specimen as preserved, exposed primarily in dorsomedial (scapulocoracoid), caudodorsal (humerus), and dorsal (radius and ulna) views (B). Interpretive line drawing (C) of B. Photograph of scapulocoracoid and proximal end of humerus in caudodorsal view (D), showing supracoracoid fenestra and other structures. Interpretive line drawing (E) of D. Abbreviations: ac, acromion; bc, bicipital crest; C, coracoid; cr, caudal ridge; dep, dorsal epicondyle; dpc, deltopectoral crest; dr, dorsal ridge; ed, epicondylar depression; fs?, fossa for M. supinator?; H, humerus; hh, humeral head; lp, lateral process; ‘mb’, ‘medial bar’; op, olecranon process; R, radius; S, scapula; scb, scapular blade; scf, supracoracoid fenestra; sta, sternal articulation; U, ulna. Picture credit: Zhou et al.

Picture credit: Zhou et al

A Relative of Microraptor

The researchers surmise that Jian changmaensis probably possessed feathers on both its arms and legs. Therefore, it likely had four wing surfaces. This arrangement may have helped it glide through the forests of Early Cretaceous China. The discovery expands the known fossil record of the Microraptorinae into north-western China. In addition, the partial pectoral girdle indicates that J. changmaensis was much larger than Microraptor. It is one of the largest microraptorines known to science. The fossil material suggests an animal with a wingspan of around a metre to 1.2 metres. This suggests that Jian would have had a wingspan comparable in size to that of the Common Buzzard (Buteo buteo).

The PNSO Microraptor figure, new for 2020 swoops into view.

The picture (above) shows a model of Microraptor.  It is the PNSO Gaoyuan model.  Microraptor had feathers on its arms and legs, and it has been speculated that it was capable of gliding.

To view the range of PNSO prehistoric animal models in stock: PNSO Age of Dinosaurs Figures.

Similarities with the Famous Jehol Biota

Scientists noted striking similarities between the Changma Basin and the famous Jehol deposits of north-eastern China. Both regions contain microraptorine dinosaurs. Furthermore, both ecosystems included early birds. The Changma deposits contain abundant remains of Gansus yumenensis. Likewise, some Jehol localities are dominated by closely related early birds.

These similarities suggest that the two regions may have shared comparable environments. Such habitats are poorly represented at many other Jehol fossil sites.

The fascinating Jehol Biota: The Jehol Biota.

To read a blog post about a new tiny dromaeosaurid dinosaur from the Jehol fossil sites: New Dromaeosaurid from Liaoning Province (Jehol Biota).

First Non-avian Dinosaur from Changma

The discovery of Jian changmaensis marks an important milestone. It represents the first non-avian dinosaur body fossil reported from the Xiagou Formation. Moreover, the fossil demonstrates that small dromaeosaurids lived alongside numerous early birds. Consequently, scientists now have a better understanding of the biodiversity preserved within the Changma Basin.

Although only part of the skeleton is known, Jian changmaensis provides valuable information. The fossil helps researchers reconstruct the distribution and evolution of microraptorines.

In addition, the discovery highlights the importance of the Changma Basin. Future finds could reveal even more dinosaurs from these remarkable deposits.

Everything Dinosaur acknowledges the assistance of a media release from the Field Museum (Chicago) in the compilation of this article.

The scientific paper: “First non-avian theropod (Dromaeosauridae, Microraptorinae) from the bird-bearing Lower Cretaceous Xiagou Formation of the Changma Basin, Gansu Province, north-western China” by Ling-Qi Zhou, Matthew C. LaManna, Ashley W. Poust, Da-Qing Li, Hai-Lu You and Jingmai K. O’Connor published in the Annals of the Carnegie Museum.

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

Scientists have identified a new species of ancient crocodylomorph from Upper Triassic rocks in southwest England. The newly named species, Galahadosuchus jonesi, lived around 215 million years ago and it represents the second species of non-crocodyliform crocodylomorph described from the Late Triassic–aged fissures of the Bristol Channel area.

Non-crocodyliform crocodylomorph fossil material is known from both sides of the Bristol Channel.  Osteoderms, teeth and bones have been found.  Most of these fossils have been assigned to the species Terrestrisuchus gracilis (Crush, 1984).  However, it is probable that T. gracilis has become a taxonomic waste basket to some extent.  Different genera of early crocodylomorphs are likely present. The discovery of Galahadosuchus jonesi, named from fossils formerly assigned to Terrestrisuchus confirms previous suggestions of under-described pseudosuchian diversity from these deposits.

The fossil specimen was discovered in 1969. However, researchers have only recently recognised that it represents a previously unknown species. The findings have been published in the academic journal “The Anatomical Record”.

A Small, Fast-moving Terrestrial Predator

Unlike modern crocodilians, Galahadosuchus was not an aquatic ambush hunter. Instead, it was a lightly built, agile, fast-running animal that spent its life on land.

Researchers describe it as resembling a reptilian greyhound. It had long, slender limbs, an upright posture and a body adapted for speed. The animal probably hunted small reptiles, amphibians and early mammals.

Galahadosuchus jonesi scale drawing (based on Pseudhesperosuchus jachaleri). Note scale bar equals 10 cm. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Several anatomical features support this interpretation. These include elongated wrist bones, tightly grouped metacarpals and a distinctive ankle structure. Together, these traits indicate that Galahadosuchus was a highly cursorial predator, related to Terrestrisuchus but a distinct genus.

Fossils from an Ancient Karst Landscape

The fossil comes from the famous fissure deposits found around the Bristol Channel area. During the Late Triassic, this region consisted of limestone uplands surrounded by hot, arid lowlands. Over time, caves and fissures formed within the limestone. The remains of animals were washed into these natural traps and became buried by sediment. As a result, the fissure deposits preserve a fascinating snapshot of life, although the exact dating of the deposits has proved controversial. For example, the geological age of these deposits and their fossil content remains unknown.

Some academics suggest that the fossils represent a biota from the youngest faunal stage of the Triassic (Rhaetian).  Moreover, that the fossils date from around 206 to 201.5 million years ago. In contrast, other researchers consider these deposits to be much older and spanning a greater interval of deep geological time.  For instance, it has been postulated that these fissure fill deposits span an age range from the Carnian to the Rhaetian (around 230 to 201.5 million years ago).

These rocks have provided numerous important vertebrate fossils including early dinosaurs and ancestors of modern lizards.

To read Everything Dinosaur’s blog post from 2021 about the discovery of an early theropod dinosaur: “Chief Dragon” from a South Wales Quarry.

Evidence of modern lizards in the Late Triassic: Cryptovaranoides is Clearly a Squamate.

Identifying a New Species

The specimen was originally assigned to Terrestrisuchus. However, a detailed study revealed important anatomical differences (autapomorphies). The research team identified thirteen anatomical traits that distinguish the fossil from known Terrestrisuchus specimens. Several of these differences involve the wrist bones, which are shorter and more robust in the new species. The differences in the morphology of the limb and wrist bones might correspond to differences in locomotory function between Terrestrisuchus and Galahadosuchus. These differences could reflect varying specialisations within Late Triassic crocodylomorphs.

Phylogenetic analysis places Galahadosuchus as a sister taxon to Terrestrisuchus. Both animals belong to a family of early crocodylomorphs known as the Saltoposuchidae.

These findings demonstrate that early crocodylomorph diversity was greater than previously recognised.

Galahadosuchus jonesi Honours an Inspirational Teacher

The species name honours David Rhys Jones, a physics teacher at Ysgol Uwchradd Aberteifi in Cardigan, Wales.

Lead author of the study, Ewan Bodenham explained that Mr Jones played an important role in encouraging his interest in science. The teacher’s enthusiasm, humour and willingness to challenge students helped inspire a future palaeontologist.

Meanwhile, the genus name combines “suchus” (crocodile) with a reference to Sir Galahad from Arthurian legend, a knight renowned for his moral uprightness. Therefore, the genus name reflects the upright stance of this reptile.

A Window into Early Crocodylomorph Evolution

The discovery of Galahadosuchus jonesi adds another important species to the rich fossil record of the Bristol Channel fissure deposits. These remarkable fossils continue to improve our understanding of life during the Late Triassic. Furthermore, they provide valuable evidence about the early evolution of crocodylomorphs, a lineage that would eventually give rise to modern crocodilians.

Everything Dinosaur Comments on Galahadosuchus jonesi

Commenting on the study, Mike from Everything Dinosaur stated:

“The fissure deposits of southwest England and South Wales continue to produce extraordinary insights into Late Triassic ecosystems. The identification of Galahadosuchus jonesi highlights just how diverse the early relatives of crocodiles had become before the end-Triassic extinction event. It also demonstrates the importance of revisiting historic museum specimens, as collections can still contain species waiting to be recognised.”

Everything Dinosaur acknowledges the assistance of the media team from University College London and the London Natural History Museum in the compilation of this article.

The scientific paper: “A second species of non-crocodyliform crocodylomorph from the Late Triassic fissure deposits of southwestern UK: Implications for locomotory ecological diversity in Saltoposuchidae” by Ewan H. Bodenham, Stephan N. F. Spiekman, Susannah C. R. Maidment, Paul Upchurch and Philip D. Mannion published in The Anatomical Record.

The Everything Dinosaur website: Dinosaur Toys and Models.

A newly named giant Tylosaurus species has been named by researchers.  The new species of Tylosaurus has been erected based on fossils found in northern Texas. This enormous predator ruled the ancient seas around 80 million years ago (Campanian faunal stage of the Late Cretaceous).  The scientific paper was published in the Bulletin of the American Museum of Natural History. The new species has been named Tylosaurus rex.  Its name translates as “King of the Protuberance Lizards.”

The name also honours the work of Texas palaeontologist John Thurmond. Decades ago, he suspected these fossils represented a different species of Tylosaurus. Fossil material had previously been assigned to T. proriger.

The T. proriger fossil material mainly comes from Kansas. These fossils are estimated to be about 84 million years old. The Texas fossil material is around 4 million years younger. Geological age of the fossils strongly suggests that the Texas fossils do indeed represent a distinct species.

The new for 2026 CollectA Tylosaurus marine reptile model.  This new figure is based on Tylosaurus proriger.

The picture (above) shows the recently introduced CollectA Age of Dinosaurs Tylosaurus figure. We think that this model is based on T. proriger.

To view the CollectA Age of Dinosaurs models in stock: CollectA Prehistoric Life Models.

The research was led by scientists from the American Museum of Natural History (New York City), the Perot Museum of Nature and Science (Dallas, Texas), and Southern Methodist University (Texas).

A New Species – Tylosaurus rex

Tylosaurus rex was not a dinosaur. Media releases might have linked this mosasaur with Tyrannosaurus rex. However, the Tylosaurus genus is more closely related to modern snakes and lizards than it is to archosaurs like T. rex. Nevertheless, like Tyrannosaurus rex, Tylosaurus rex was probably an apex predator within its ecosystem. Mosasaurs were powerful ocean hunters. They evolved from land-dwelling lizards. Over time, they adapted fully to life in the sea.

The researchers estimate that Tylosaurus rex reached lengths of around 13 metres. Its huge skull contained strong jaws and serrated teeth. These adaptations helped it tackle large prey.

Lead author of the study Amelia Zietlow (American Museum of Natural History) commented that everything tends to be bigger in Texas, including mosasaurs.  Several autapomorphies were identified the allowed the research team to confidently reassign T. proriger material this new species.

A Violent Ancient Predator

One remarkable fossil specimen shows evidence of serious injuries. The animal had damage to its snout and jaw. Researchers think another giant Tylosaurus caused these wounds. In other words, these marine reptiles may have fought each other violently. Interestingly, this behaviour mirrors injuries found in Tyrannosaurus rex fossils. That similarity partly inspired the dramatic species name.

The Western Interior Seaway

During the Late Cretaceous, much of Texas lay beneath a shallow sea. This ancient waterway formed part of the famous Western Interior Seaway. The seas teemed with life. Giant sharks, fish, turtles and marine reptiles shared these waters.

Tylosaurus rex probably hunted almost anything it could overpower. Scientists think it likely preyed upon fish, turtles, and other marine reptiles.

Dramatic scene from the Western Interior Seaway painted by Burian. Picture credit: Zdeněk Burian.

Picture credit: Zdeněk Burian

Revisiting Old Fossils

This discovery highlights an important point in palaeontology. Museum collections can still contain unknown species. Some Tylosaurus rex fossils had sat in museum collections for decades. Researchers only recognised their true identity after careful re-examination. The study also updated mosasaur evolutionary data. According to the research team, scientists have relied on outdated datasets for many years.

As a result, this new study could reshape how researchers understand mosasaur evolution.

Mike from Everything Dinosaur commented”

“The discovery of Tylosaurus rex demonstrates how much there is still to learn about Russellosaurina clade of mosasaurs. Many spectacular fossils remain hidden in museum collections. Furthermore, new technology and fresh analysis continue to reveal ancient secrets. This newly described giant mosasaur was one of the largest marine predators of its time. Without doubt, it would have been an intimidating sight in the ancient seas of Texas.”

The scientific paper: “A gigantic new species of Tylosaurus (Squamata, Mosasauridae) from Texas: and a revised character list for phylogenetic analyses of Mosasauridae” by Amelia R. Zietlow, Michael J. Polcyn and Ronald S. Tykoski published in the Bulletin of the American Museum of Natural History.

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

Although T. rex forelimbs look tiny compared to its huge body and head, the arms of T. rex were still powerful and although they may not have played a role in prey capture and submission, they still had their uses. At Everything Dinosaur, we receive lots of questions about dinosaurs.  Frequently, the questions focus on theropod dinosaurs.  Moreover, we tend to get quizzed on the “King of the Tyrant Lizards” – Tyrannosaurus rex.  For example, we often get asked why did T. rex have small arms?

Estimates of up to 9 tons in weight. A huge Tyrannosaurus rex skeleton cast on display.  Note the tiny arms which are disproportionately small. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Why Did T. rex Have Small Arms?

This question has puzzled palaeontologists for many years. Indeed, when Barnum Brown first uncovered substantial fossil remains that were to lead to the erection of this genus, he thought the arm material found in association with the other theropod remains belonged to a different dinosaur. However, scientists now know that tyrannosaurs and other meat-eating dinosaur lineages that evolved a large body size, also evolved reduced forelimbs.

Tyrannosaurs, abelisaurs, carcharodontosaurids, megalosaurs and ceratosaurs are all theropod lineages that evolved reduced/vestigial forelimbs.  This is described as convergent evolution.  Numerous theories have been put forward. Recently, we wrote a blog post highlighting research that examined the relationship between theropod skull robustness and forelimb size. The study concluded that the tiny arms of some theropod dinosaurs evolved because their heads became the main weapons for subduing prey.

To read our blog post about a recently published academic paper that reviewed arm size and skull robusticity in theropod dinosaurs: New Study Solves Mystery of Tiny Theropod Arms.

The new for 2024 PNSO Tyrannotitan chubutensis dinosaur model. In the study into the relationship between skull robusticity and forelimb reduction, the second ranked theropod (behind T. rex) was Tyrannotitan chubutensis. This carcharodontosaurid was found to have an extremely robust and powerful skull, yet its forelimbs were extremely small.

Tyrannotitan chubutensis

In the research published in the “Royal Society Proceedings B”, the carcharodontosaurid Tyrannotitan chubutensis was found to rank second on the cranial robusticity scale developed by the scientists. Tyrannotitan lived millions of years before super-sized tyrannosaurs evolved.  This suggests that reduced forelimb adaptations evolved several times in the Theropoda.

Why did T. rex have small arms? One possible answer therefore is that jaws rather than claws become the most effective method of securing a meal.

Intriguingly, other theories have been put forward.  For instance, it has been suggested that reduced forelimbs evolved in theropods to help keep them out of the way when attacking another animal.  A Triceratops or Edmontosaurus for that matter would have been capable of inflicting severe damage to the arm of a tyrannosaur if it could bite it.  Perhaps, reduced forelimbs evolved to permit carnivorous dinosaurs to lunge headfirst at prey, without risking losing a limb.

Furthermore, if some theropods were pack hunters small limbs may have been an advantage when social feeding took place. Short arms helped reduce the risk of injury. Adult tyrannosaurs probably fed together at carcasses. Large, powerful predators snapping at each other could accidentally damage long forelimbs. Reduced forelimbs may have been safer in crowded feeding situations.

T. rex Arms Were Small but Strong

The arms of Tyrannosaurus rex were only about one metre long. However, palaeontologists think these limbs were heavily muscled. Each arm ended in two large claws. Studies suggest the forelimbs were strong.  They could have helped the animal to get up from a resting position, or perhaps they played a role in mating behaviour/courtship display. Some scientists think the arms helped hold struggling prey close to the body.

The PNSO 1:35 scale T. rex dinosaur model in a resting pose.  Getting up from a resting position might help answer the question why did T. rex have small arms?

Even though the arms seem small, they were not weak or useless.  They were probably held close to the body as shown in the picture (above) of the PNSO resting Tyrannosaurus rex figure. Indeed, the strong forelimbs and those tiny but robust two digits on each hand could have helped this dinosaur to stand upright after resting.

To view the range of PNSO models in stock: PNSO Scientific Art Figures.

Why Were the Arms So Short?

Scientists are still debating exactly why T. rex evolved such short forelimbs. The enormous skull and powerful jaws of T. rex may explain the reduced arm size. Its bite force was among the strongest of any land animal. As the head became larger and more specialised for hunting, the forelimbs may have become less important.

In simple terms, T. rex, like many other theropods probably relied on its jaws rather than its claws to capture prey.

Although small, the forelimbs probably still had a purpose. However, there is currently no single explanation accepted by all palaeontologists. Perhaps, the recently published paper evaluating theropod skull robusticity and forelimb reduction provides a plausible answer.

A Famous Dinosaur Mystery

Why did T. rex have small arms? It is a famous dinosaur mystery and a popular question.  Palaeontologists know that many different types of theropod dinosaur had reduced arms.  This is an example of convergent evolution.  The reduced forelimbs of theropod dinosaurs are one of their most fascinating features.

Mike from Everything Dinosaur commented:

“While scientists continue to study tyrannosaurs and other theropods it is clear that small forelimbs evolved independently in many theropod lineages.  Small arms must have had some form of evolutionary advantage as many theropods with reduced forelimbs were the apex predators in their ecosystems.”

The multi-award-winning Everything Dinosaur website: Scientifically Accurate Dinosaur Toys.

Why did T. rex have tiny arms?  This is a question we get asked a lot at Everything Dinosaur.  Ironically, several, not closely related theropod lineages show forelimb reduction. Tyrannosaurus rex had famously small arms, but so did lots of other large meat-eating dinosaurs. A new study suggests that the tiny arms of some theropod dinosaurs evolved because their heads became the main weapons for securing a meal.

The “Tristan” Tyrannosaurus rex specimen on display at the Museum für Naturkunde Berlin. This theropod has a huge skull and famously small arms. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Why Did T. rex Have Tiny Arms?

This might be a popular question from model collectors. However, scientists tend to take a broader view. For example, if forelimb reduction is observed in the fossil remains of numerous theropods, then it could be concluded that reduced forelimbs evolved convergently. The new study published in the “Proceedings of the Royal Society B” examined eighty-two species of theropod dinosaur. Researchers found a strong link between powerful skulls and reduced forelimbs. In simple terms, as some meat-eating dinosaurs evolved stronger bites and more robust heads, their arms became less important.

The Everything Dinosaur Evolution Tyrannosaurus rex model (EDE001) shown in anterior view. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows the recently introduced Everything Dinosaur Evolution 1:33 scale Tyrannosaurus rex model shown in anterior view.  The forelimbs are in proportion, and they are barely noticeable compared to the deep, broad body and the huge head.

To view the range of Everything Dinosaur Evolution models: Everything Dinosaur Evolution Tyrannosaur Models.

The team developed a theropod cranial robusticity scoring system. Reduced or vestigial forelimbs evolved in at least five theropod lineages in concert with increased cranial robusticity and gigantism. Therefore, tiny arms evolved several times within the Theropoda.

Reduced/Vestigial Forelimbs Evolved Several Times

It is natural for most people to associate tiny arms with Tyrannosaurus rex. However, the scientists identified five different theropod lineages with reduced/vestigial forelimbs in animals with a large body mass.

• Tyrannosaurids
• Carcharodontosaurids
• Abelisaurids
• Megalosaurids
• Ceratosaurids

Importantly, these groups were not all closely related. Furthermore, it can be concluded that the same body plan evolved independently several times. This is known as convergent evolution.

The new for 2026 CollectA Deluxe Meraxes gigas figure. This replica of a super-sized carcharodontosaurid theropod had reduced forelimbs. This is an example of convergent evolution.

The giant carcharodontosaurid Meraxes gigas, fossils of which come from Upper Cretaceous deposits in Patagonia is another example of a large theropod with greatly reduced forelimbs. The picture (above) shows the new for 2026 CollectA Deluxe Meraxes model.  The tiny arms and small hands with three digits have been beautifully sculpted.

To view the CollectA Deluxe model range: CollectA Deluxe Prehistoric Animal Models.

Robust and Powerful Skull Replaced Strong Arms

The research team concluded that theropod skulls became increasingly important for attacking prey. As a result, the arms gradually reduced in size. Lead author Charlie Roger Scherer (University College London) explained that the head effectively “took over” from the forelimbs during hunting.

He stated:

“Everyone knows the T. rex had tiny arms but other giant theropod dinosaurs also evolved relatively small forelimbs. The Carnotaurus had ridiculously tiny arms, smaller than the T. rex. We sought to understand what was driving this change and found a strong relationship between short arms and large, powerfully built heads. The head took over from the arms as the method of attack. It’s a case of ‘use it or lose it’ – the arms are no longer useful and reduce in size over time.”

The scientists found that reduced forelimbs were more strongly linked to skull robustness than overall body size. This was a key discovery. Previously, some researchers suggested that small arms were simply a side effect of giant body size. However, the new study challenges that idea.

Some theropods with tiny arms were not especially huge. For example, Majungasaurus from the Late Cretaceous of Madagascar weighed around 1.6 tonnes. Although large, it had a body weight four times lighter than Tyrannosaurus rex. Despite this, it still had very reduced forelimbs and a heavily built skull.

Majungasaurus models from Haolonggood. The Deng Fei Majungasaurus figure is shown in lateral view with the blue-tailed Ou Peng shown on the right.  These abelisaurid theropods had a robust skull and tiny arms.

To view the Haolonggood range of prehistoric animals: Haolonggood Prehistoric Animal Figures.

An Evolutionary Arms Race

The researchers think gigantic prey animals may have driven this evolutionary trend. During the Jurassic and Cretaceous, enormous plant-eating dinosaurs (sauropods) dominated many ecosystems. They suggest that the evolution of reduced forelimbs was potentially influenced by an upward trend in prey body size. Huge sauropods and other large herbivores may have led to predators evolving stronger skulls and jaws.

Trying to grasp a giant sauropod with relatively small claws may not have been effective. Instead, attacking with powerful jaws and holding onto prey with the mouth could have offered advantages.  As a result, some theropod lineages developed deeper skulls, stronger jaw muscles which increased bite forces.  The researchers described this process as an evolutionary arms race between predators and prey.

The “Tristan” Tyrannosaurus rex specimen shown in anterior view. The robust and powerful skull contrasts with the reduced forelimbs. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Measuring Skull Strength

For this study, the scientists developed a new method for measuring skull robustness. Several factors were included in their calculations, such as skull shape, bite force, skull compactness and the thickness of skull bones. Compact skulls tend to resist bite force stresses better than long, narrow skulls. On the cranial robusticity scale Tyrannosaurus rex was ranked highest. This helps to answer the question why did T. rex have tiny arms?

Intriguingly, Tyrannotitan (T. chubutensis) a giant carcharodontosaurid from the Early Cretaceous of Argentina was ranked second on the cranial robusticity scale. Tyrannotitan lived more than thirty million years before T. rex. It demonstrates that this trend evolved long before tyrannosaurs dominated North America.

A Tyrannotitan chubutensis scale drawing has been commissioned in preparation for the arrival of the new PNSO Tyrannotitan figure. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Different Dinosaurs Reduced Their Arms in Different Ways

Although several theropod lineages evolved tiny forelimbs, they did not all shrink them in the same manner. For example, abelisaurids reduced the hands and lower arms dramatically. In contrast, tyrannosaurids reduced the entire forelimb more evenly. This suggests that different developmental pathways produced similar outcomes.

In evolutionary biology, this is another fascinating example of convergent evolution. Different dinosaur groups independently evolved comparable solutions to similar ecological challenges.

The study provides important new insights into theropod evolution. It also helps explain one of the most famous dinosaur features in popular culture. The tiny arms of Tyrannosaurus rex were probably not useless. Instead, they were simply less important as the skull became the primary hunting tool. As theropods evolved increasingly powerful bites, natural selection may have favoured predators that relied more on jaws than claws.

The result was a series of formidable carnivores with massive skulls, bone-crushing bites and surprisingly tiny arms.

An Answer to the Question Why Did T. rex Have Tiny Arms?

This is a fascinating study. Perhaps, the skulls of alvarezsaurid dinosaurs can be examined using this new statistical analysis.  After all, these lightly built theropods had greatly reduced forelimbs too.  This analytical method could also provide a new perspective on avian dinosaurs – birds.

We may have an answer to one of our most often asked questions – why did T. rex have tiny arms?

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

The scientific paper: “Drivers and mechanisms of convergent forelimb reduction in non-avian theropod dinosaurs” by Charlie Roger Scherer, Elizabeth Steell and Paul Upchurch published in the Proceedings of the Royal Society B.

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

A remarkable new study suggests that Homo erectus populations in East Asia may have co-existed and interbred with Denisovans hundreds of thousands of years ago. The research provides the first molecular evidence linking these ancient human lineages.  This recently published research demonstrates how new protein recovery and analysis techniques can enhance data retrieved in association with hominin fossil discoveries.

The paper, published in the journal “Nature”, analysed fossil teeth from China dating to around 400,000 years ago (Chibanian stage of the Pleistocene Epoch). Scientists extracted ancient proteins preserved inside the dental enamel. As a result, they uncovered genetic clues that may reshape our understanding of human evolution in Asia.

Ancient Proteins from Fossil Teeth

The researchers studied six Homo erectus teeth from three famous Chinese fossil sites. These included Zhoukoudian, the home of “Peking Man”. Zhoukoudian on the North China Plain is now a UNESCO World Heritage site.  The Pliocene and Pleistocene deposits have preserved the remains of early hominins, and the site has been the focus of intense research.

“Peking Man” is thought to represent a sub-species of Homo erectus.  A fossil tooth discovered in 1921 and subsequent hominin fossil discoveries has helped palaeoanthropologists to re-define aspects of hominin evolution. For example, H. erectus is thought to be a direct ancestor of modern humans (H. sapiens).  In addition, whilst it is thought that Homo erectus originated in Africa, it was the first hominin to migrate extensively, with fossil remains found throughout Asia.

Importantly, the team used palaeoproteomics (the study of ancient proteins), rather than ancient DNA analysis. Ancient DNA rarely survives in fossils this old. However, proteins locked within tooth enamel can persist for far longer.

The scientists identified two unusual amino acid variants in a tooth-development protein called ameloblastin. One variant appears unique to East Asian Homo erectus. The second variant proved even more intriguing. Previously, it had only been identified in Denisovans.  The Denisovans are an enigmatic and poorly known archaic hominins that lived in Asia during the middle to late Pleistocene. They are named after the Denisova Cave in the Altai Mountains of Siberia, Russia, where their fossils were first discovered in 2008.

To read an article from 2013 highlighting research into the Denisovans: The Mystery of the Denisovans.

Evidence of Ancient Interbreeding?

The shared protein variant hints that Homo erectus and Denisovans may have interbred in East Asia. If correct, this would add another layer of complexity to the human evolution story. Palaeoanthropologists have long suspected that ancient human species interbred with one another. For example, analysis of other hominin fossil discoveries revealed modern humans interbred with both Neanderthals and Denisovans. Moreover, traces of Denisovan ancestry survive in some living populations today, especially in Southeast Asia and Oceania.

Now, this study suggests that these ancient interactions may have started much earlier than previously thought.

Models depicting three hominins. Homo erectus (left), H. neanderthalensis (centre) and a modern human (H. sapiens) right. The Homo erectus is holding a flaming stick a reference to their tool making abilities and control of fire.

The image (above) shows three figures that help to illustrate hominin evolution.  The Homo erectus figure reflects the control of fire that this species is thought to have possessed.  The models come from an “Evolution of Man” model set produced by Safari Ltd.

To view the range of prehistoric figures including early hominins available: Prehistoric World Figures.

A Complicated Human Family Tree

Scientists know that several human lineages overlapped across Africa and Eurasia during the middle to late Pleistocene. However, their exact relationships remain poorly understood. This new research adds more evidence that ancient humans did not evolve in isolated branches. Instead, different populations probably met and exchanged genes repeatedly.

Interestingly, some researchers now wonder whether certain Chinese fossils traditionally assigned to Homo erectus might actually belong to Denisovan-related groups.

A new species of hominin Homo longi: “Dragon Man” from North-eastern China.

Hominin Fossils Still Hold Molecular Secrets

The study also highlights the growing importance of protein analysis in palaeoanthropology. Recovering DNA from hominin fossil remains extremely difficult. Nevertheless, palaeoproteomics is providing new perspectives on human evolution.  Ancient proteins recovered from hominin teeth may provide evidence to help scientists to better understand human evolution.

As more fossils undergo molecular analysis, researchers may finally untangle the complicated evolutionary history of ancient humans in Asia. Furthermore, how our own species evolved and its complex taxonomic relationship with other hominin taxa.

For now, these ancient teeth provide tantalising evidence that Homo erectus and Denisovans once shared more than just the same landscape. They may also have shared genes.

The scientific paper: “Enamel proteins from six Homo erectus specimens across China” by Qiaomei Fu, Zhongyou Wu, E. Andrew Bennett, Song Xing, Qiang Ji, Zhe Dong, Huiyun Rao, Xuejun Gu, Yizhao Dang, Jun Xing, Kai Zhou and Xiaotian Feng published in the journal Nature.

For scientifically accurate models of ancient hominins and other Pleistocene fauna: Models of Prehistoric Life.