All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.

Articles, features and information which have slightly more scientific content with an emphasis on palaeontology, such as updates on academic papers, published papers etc.

12 04, 2023

Reduction in Mammal Skull Bones led to Evolutionary Success

By |2023-04-12T14:37:19+01:00April 12th, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A new study suggests that the key to the evolutionary success of the early mammals, was to stay small, eat insects and to reduce the number of bones in their skull. The reduction of mammalian skull bones led to a more efficient absorption of bite forces and this adaptation helped mammals to diversify and to ultimately dominate modern ecosystems.

The study, published in the academic journal “Communications Biology” contrasts the skulls of other vertebrates and mammalian ancestors with mammals known from the Jurassic and Cretaceous. In many vertebrate groups such as reptiles and fishes, the skull and lower jaw are composed of numerous bones. This configuration was also seen in the earliest ancestors of modern mammals that lived over 300 million years ago (Cynodontia). However, during evolution the number of bones in the skull was reduced.

A digital model of a Hadrocodium skull.
Digital skull model of the small-sized Jurassic mammal ancestor Hadrocodium wui with coin providing scale. Picture credit: Dr Stephan Lautenschlager, University of Birmingham.

A Reduction in Mammalian Skull Bones

Computer simulations based on three-dimensional skull models permitted the research team to examine bite forces and skull stresses. Their research demonstrates that reducing the number of skull bones did not lead to higher bite forces or increased skull strength as postulated previously.

Instead, the researchers, found that the skull shape of these early mammals redirected stresses during feeding in a more efficient way.

Lead author for the study, Dr Stephan Lautenschlager, Senior Lecturer for Palaeobiology (University of Birmingham) explained:

“Reducing the number of bones led to a redistribution of stresses in the skull of early mammals. Stress was redirected from the part of the skull housing the brain to the margins of the skull during feeding, which may have allowed for an increase in brain size.”

Switching Diets

The study, which also involved scientists from the University of Hull, Bristol University, the University of Chicago and the London Natural History Museum, demonstrated that alongside the reduction of skull bones, early mammals also became a lot smaller. Some Mammaliaformes for example, had skulls around 1 cm in length.

This miniaturisation considerably restricted the available food sources and early mammals adapted to feeding mostly on insects.

Dr Lautenschlager added:

“Changes to skull structure combined with mammals becoming smaller are linked with a dietary switch to consuming insects – allowing the subsequent diversification of mammals which led to development of the wide-range of creatures that we see around us today.”

Reduction in mammalian skull bones led to evolutionary success.
Life reconstruction of Hadrocodium wui. This Jurassic mammal is depicted hunting insects, illustrating how the adoption of an insectivorous diet and miniaturisation played a significant role in mammal evolution. Picture credit: Dr Stephan Lautenschlager, University of Birmingham.

Hadrocodium wui

One of the mammaliaforms used in the study, is Hadrocodium wui fossils of which are known from the Early Jurassic (Sinemurian faunal stage) of China. At around ten centimetres long, this tiny animal was a very small and inconsequential member of the Lufeng Formation biota, which was dominated by dinosaurs such as Lufengosaurus.

Drawing of Ngwevu intloko (based on Lufengosaurus).
An illustration of Lufengosaurus. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The image (above) is a drawing of the Early Jurassic sauropodomorph Lufengosaurus.

For models and replicas of Early Jurassic dinosaurs and other prehistoric animals: CollectA Age of Dinosaurs Models and Figures.

However, H. wui is considered to be very close to the Mammaliaformes lineage that led directly to modern mammals (Mammalia).

To read an earlier blog post by Everything Dinosaur that examined how brain size might have increased in early mammals as a result of an improving sense of smell: Brain Size in Early Mammals Linked to Sense of Smell Development.

Staying Small and Eating Insects

The research team concludes that miniaturisation and staying small, combined with a reduction in skull bones and a switch to an insectivorous diet allowed the ancestors of modern mammals to thrive in the shadows of the Dinosauria. Having nocturnal habits may also have permitted these animals to carve out their own ecological niches in dinosaur dominated ecosystems.

It was not until dinosaurs became extinct at the end of the Cretaceous, some 66 million years ago, that mammals had a chance to further diversify and reach the large range of body sizes seen in many extant mammals today.

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

The scientific paper: “Functional reorganisation of the cranial skeleton during the cynodont–mammaliaform transition” by Stephan Lautenschlager, Michael J. Fagan, Zhe-Xi Luo, Charlotte M. Bird, Pamela Gill and Emily J. Rayfield published in Communications Biology.

9 04, 2023

Hominid or Hominin? A Helpful Explanation

By |2024-01-02T20:05:59+00:00April 9th, 2023|Adobe CS5, Main Page, Palaeontological articles, Teaching|0 Comments

Everything Dinosaur team members have produced numerous blog posts documenting fossil discoveries and research into human evolution. Scientists are gradually gaining a better understanding of the evolution of our own species (Homo sapiens). Readers may have noticed a change in the use of the terms that describe members of the Homo genus, related genera and their ancestors.

For example, the terms “hominid” and “hominin”. In the past, these terms were interchangeable. Both hominid and hominin referred to the group of apes consisting of modern humans, extinct humans and all our immediate ancestors. The definition of these terms has changed. This change can lead to confusion, so, Everything Dinosaur thought it might be helpful to explain what “hominid” and “hominin” now refer to.

Hominid (Hominidae Family)

The term “hominid” has been given a wider definition, encompassing all the Great Apes. It now encompasses all modern and extinct Great Apes (humans, chimpanzees, including the bonobos, gorillas, orangutans and their immediate ancestors.

Hominin and Hominid
The Great Apes – extant and extinct (humans, gorillas, orangutans, chimpanzees, bonobos and all their immediate ancestors) – defining hominids (Hominidae Family).

Hominin Defined

The term “hominin” now refers to a narrower group. This group consists of modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus and Ardipithecus).

Hominin and Hominid
The term hominin defined: modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Ardipithecus and Paranthropus).

Hominid or Hominin?

The change in definition has occurred as palaeoanthropologists have altered the way that apes are classified. In the previous taxonomy, humans were distinct and separate from all other apes. They were placed into their own, unique family the Hominidae or hominids, one of three families classifying the apes.

Scientists have revised their classifications to develop more up-to-date evolutionary trees. The revision has reduced the number of families recognised to just two. All the Great Apes (including humans) are placed into the same family, the Hominidae or hominids. The next branching of this evolutionary tree divides the orangutans into one subfamily and all the remaining Great Apes into another subfamily. Then at the tribe level, gorillas, chimpanzees and humans separate onto different branches of the evolutionary tree with humans in the Hominini or hominin branch.

To view models and replicas of extinct Great Apes and ancestors of modern humans: Everything Dinosaur Prehistoric Animal Models and Figures.

Everything Dinosaur acknowledges the assistance of post produced by the Australian Museum (Sydney) in the compilation of this article.

Visit Everything Dinosaur’s award-winning website: Everything Dinosaur.

3 04, 2023

A Superb Triceratops Skull on Display

By |2024-01-02T20:09:29+00:00April 3rd, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|1 Comment

Visitors to the Berlin Naturkundemuseum (Germany) will be able to see an amazing Triceratops skull on display as part of an exhibition entitled “Dinosaurs! Age of the Giant Lizards”.

The impressive cranium, complete with horns and an imposing head shield measures two metres long and it was found in Lance Creek Formation deposits (Wyoming, USA) back in 2020. The fossil was discovered by an amateur fossil hunter and after preparation in Canada, the current owner Lars Fjeldsoe-Nielsen has lent the stunning specimen to the Museum für Naturkunde in Berlin.

Triceratops Skull on Display
The magnificent Triceratops skull on display in the “Dinosaurs! Age of the Giant Lizards” gallery at the Berlin Naturkundemuseum. Picture credit: Lukasz Papierak.

Horned Dinosaur Skull

The Triceratops specimen has been nick-named “Amalie” after the daughter of the owner. It is not known whether the skull fossil is from a female or male Triceratops. Both males and females sported neck frills and horns.

Numerous ornithischian dinosaurs are known from the Lance (Creek) Formation. The strata were deposited during the Maastrichtian faunal stage of the Late Cretaceous (69-66 million years ago). The fossils found in these rocks represent a diverse dinosaur dominated terrestrial fauna that thrived prior to the mass extinction event that saw the demise of the non-avian dinosaurs, including ceratopsians like Triceratops.

PNSO Doyle the Triceratops (2022)
The new for 2022 PNSO Doyle the Triceratops 1:35 scale model comes complete with a scale model of a Triceratops skull.

The picture above shows a Triceratops model and skull, which is part of the PNSO Age of Dinosaurs series.

To view the PNSO prehistoric animal models and figures available from Everything Dinosaur: PNSO Age of Dinosaurs Models and Replicas.

Triceratops Skull on Display

A spokesperson from Everything Dinosaur commented that they were unsure as to the Triceratops species that “Amalie” represented. They explained that both Triceratops horridus and an as yet, not fully described Triceratops species are associated with the Lance Formation.

Johannes Vogel, Director General of the Museum für Naturkunde Berlin thanked the owner for lending this wonderful specimen and stated:

“The Museum für Naturkunde Berlin would like to express its sincere thanks to Mr Fjeldsoe-Nielsen for this further generous loan. This will enable research museums like ours to get visitors excited about nature and explore the objects.”

The exhibition “Dinosaurs! Age of the Giant Lizards” is due to run until the end of the year.

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

1 04, 2023

How Big was a T. rex Brain?

By |2023-05-08T12:35:00+01:00April 1st, 2023|Adobe CS5, Dinosaur Fans, Main Page, Palaeontological articles, Photos, Photos/Pictures of Fossils, Teaching|0 Comments

Everything Dinosaur team members were sent a question by a young dinosaur fan who wanted to know how big was the brain of T. rex? We put our own brains trust to work on this intriguing question.

Having a large brain does not necessarily indicate intelligence, how that organ is configured, and its complexity can provide neuroscientists with an insight into the intelligence of organisms.

Ironically, a controversial study published earlier this year, postulated that Tyrannosaurus rex might have been as smart as a primate, it may have possessed a comparable number of brain cells to that of a monkey.

How big was the brain of T. rex?
An endocast of the brain of T. rex derived from internal moulds of the brain case. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

How Big was the Brain of T. rex?

CAT scans of theropod skulls have enabled palaeontologists to trace nerve pathways and to build up a picture of what some brains of dinosaurs might have looked like. The Tyrannosaurus rex fossil material known as Stan (BHI3033), has provided researchers with a detailed understanding of T. rex brain function. For example, fifty percent of the brain volume was dedicated to analysing smells. Hence the assertion that the sense of smell was extremely important to this carnivore.

As for brain size, estimates vary, but a recent paper published in the Journal of Comparative Neurology estimated the T. rex brain to have weighed around 350 grammes, and endowed this predator with considerable intelligence, putting the “King of the Tyrant Lizards” on a par with extant monkeys.

To read an article from 2013 that looks at research that indicated that dinosaurs had complex brains and postulated that they were capable of sophisticated behaviours similar to modern birds and mammals: Scientists Create a Detailed Map of a Dinosaur’s Brain.

Capable of Tool Use?

Author of the recently published paper, Dr Suzana Herculano-Houzel from the Department of Psychology at Vanderbilt University (Tennessee), postulates that Tyrannosaurus rex had approximately 3 billion cerebral neurons, a greater number than found in baboons.

Beasts of the Mesozoic T. rex model in 1:18 scale
The image of the Beasts of the Mesozoic Tyrannosaurus rex model in 1:18 scale that features on the back of the product packaging. A recent research paper has suggested T. rex was as clever as a monkey. Picture credit: Everything Dinosaur.

The picture (above) shows an image of an articulated Tyrannosaurus rex from the Beasts of the Mesozoic range. To view this range of prehistoric animal figures: Beasts of the Mesozoic Models and Figures.

Using data on living birds and reptiles, Dr Herculano-Houzel inferred the number of neurons extinct creatures had based on calculations of brain mass, including many theropods such as Allosaurus, Archaeopteryx and T. rex.

Writing in the “Journal of Comparative Neurology”, a publication edited by Dr Herculano-Houzel, the doctor extrapolated how many brain cells T. rex possessed in its cerebrum (telencephalon), the most highly advanced part of the brain associated with higher cognitive functions.

Dr Herculano-Houzel postulates that Tyrannosaurus rex would have matured rapidly, lived to about forty years of age and was smart enough to use tools and to pass on acquired knowledge to offspring.

Controversial Ideas

Summarising her research, the doctor concludes:

“That theropods such as Tyrannosaurus and Allosaurus were endotherms with baboon and monkey-like numbers of telencephalic neurons, respectively, which would make these animals not only giant but also long-lived and endowed with flexible cognition, and thus even more magnificent predators than previously thought.”

How big was the brain of T. rex.
T. rex brain endocast. Was T. rex really smart? Picture credit: Everything Dinosaur.

As Clever as a Primate!

The paper has attracted scepticism from palaeontologists and other researchers. Gaining an understanding of the neuronal composition of the brains of dinosaurs would provide fundamental insights into their behavioural and cognitive capabilities.

However, brain tissue is rarely fossilised and to achieve her calculations Dr Herculano-Houzel assumed that the entire volume of the braincase was filled by brain tissue. This may not have been so. Perhaps, less than fifty percent of the braincase of T. rex was filled with brain tissue. Dinosaur brains could have been considerably smaller than the size postulated in the scientific paper.

In addition, how the brain is configured, its composition, if you like how it is “wired”, will have a significant impact on an organism’s intelligence.

Claiming that theropods such as Tyrannosaurus and Allosaurus were “the primates of their times”, is exceptionally difficult to substantiate in the absence of a living animal to study.

To read an article from October 2016 about the remarkable discovery of a preserved partial iguanodontid brain: Dinosaur Brain from Southern England.

Bird Brains

Assessing intelligence is challenging, even in living creatures. Pigeons for example, would perhaps not be regarded by many people as being particularly smart, but these avian dinosaurs are capable of remarkable feats of navigation. Many birds demonstrate advanced cognitive abilities such as corvids (crows and their relatives) using tools. Crows have much smaller brains than most monkeys, they have far fewer cerebral neurons but they can outperform some primates when it comes to cognitive assessment tasks.

Dr Herculano-Houzel argues that estimating neuron counts from brain mass is a method that has been applied to hundreds of mammal, bird, and non-avian dinosaur species, the methodology is robust.

However, claiming that T. rex was a smart as a monkey is quite a leap.

The Dinosaur Renaissance

A spokesperson from Everything Dinosaur commented:

“The research paper is free to access, so readers can make up their own minds. Whilst it is extremely challenging to try to work out how intelligent an extinct animal was, the days of regarding dinosaurs as creatures so stupid that they were an evolutionary dead end are long gone.”

The spokesperson added:

“Since the 1960s and the work of palaeontologist John Ostrom, the view of the Dinosauria has fundamentally changed. These animals were perfectly adapted to their environments and they were capable of complex behaviours just like mammals and their close relatives the birds. Just how smart T. rex was is difficult to quantify and validate with scientific evidence. Along with other theropods such as the dromaeosaurids and the oviraptorids these predators might have demonstrated very complex behaviours derived from their cognitive abilities.”

Unfortunately, as we are unlikely to ever observe a living non-avian dinosaur, assessments regarding dinosaur intelligence remain speculative.

How Big was the Brain of T. rex? Something to Ponder

However, the idea of a smart, 7 tonne carnivore measuring in excess of 12 metres long, it makes you think…

The scientific paper: “Theropod dinosaurs had primate-like numbers of telencephalic neurons” by Suzana Herculano-Houzel published in the Journal of Comparative Neurology.

30 03, 2023

New Study Suggests Tyrannosaurus rex Had Lips

By |2024-01-02T16:06:41+00:00March 30th, 2023|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Large, predatory theropod dinosaurs are often portrayed as fierce-looking monsters, with huge and highly visible teeth. These teeth are visible over the jaw line when the meat-eating dinosaur’s mouth is closed. This is reminiscent of the appearance of modern crocodilians, which after all, are closely related to fellow archosaurs such as the theropod members of the Dinosauria. However, a new study suggests predatory dinosaurs had scaly, lizard-like lips. Even Tyrannosaurus rex had lips according to a new paper published in the academic journal Science.

Tyrannosaurus rex had lips.
A juvenile Edmontosaurus disappears into the enormous, lipped mouth of Tyrannosaurus. Picture credit: Mark Witton.

Tyrannosaurus rex Had Lips

The researchers including Dr Mark Witton (University of Portsmouth) and the study lead author Assistant Professor Thomas M. Cullen (Auburn University, Alabama) suggest that carnivores such as Tyrannosaurus rex did not have permanently exposed teeth. Films such as “Jurassic Park”, many palaeoartists and numerous model manufacturers have got it wrong. Instead, these dinosaurs had scaly lips, covering and sealing their mouths.

The debate as to whether theropod dinosaurs such as Giganotosaurus, Velociraptor, T. rex and Allosaurus had lips has gone on for some time. Did these dinosaurs have perpetually visible upper teeth that hung over their lower jaws and were therefore exposed and on view even with the jaw closed? The researchers suggest that dinosaurs such as Tyrannosaurus rex did not have a smile like a crocodile. Theropods possessed lips similar to those of lizards and the ancient reptile Tuatara, the only extant member of the Rhynchocephalia.

Detailed Study

In the most detailed study concerning the presence or otherwise of extraoral tissue in the Theropoda conducted to date, the researchers examined the tooth structure, wear patterns and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than the mouths of crocodilians.

Tyrannosaurus rex skull and head reconstructions.
T. rex skull and head reconstructions. Picture credit: Mark Witton.

These lips were probably not muscular, like those of mammals. Most reptile lips cover their teeth but cannot be moved independently, a reptile can’t curl its lips back and snarl like a dog. They could not make the sort of movements that we might associate with our faces or that of other mammals.

Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada and a co-author of the study stated:

“Palaeontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialised.”

The research team concluded that theropod teeth were extremely similar to the teeth of monitor lizards (varanids). The teeth are thought to have functioned in the same way, so perhaps monitor lizards such as the Komodo dragon (Varanus komodoensis) can be favourably compared to extinct animals such as theropod dinosaurs, even though the Varanidae as members of the Squamata, are only very distantly related to the Dinosauria.

Upending Popular Theropod Depictions

Co-author Dr Mark Witton (University of Portsmouth) explained:

“Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries — Jurassic Park and its sequels, Walking with Dinosaurs and so on. Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

The Implications of “Tyrannosaurus rex Had Lips”

The results of the study, found that tooth wear in lipless animals was markedly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying they were not too big to cover with lips.

Furthermore, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, were more lizard-like in dinosaurs than crocodile-like. In addition, modelling mouth closure of lipless theropod jaws showed that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.

Tyrannosaurus rex bellowing with its mouth shut, like a vocalising alligator.
Tyrannosaurus rex bellowing with its mouth shut, like a vocalising alligator. Picture credit: Mark Witton

Kirstin Brink (Assistant Professor of Palaeontology at the University of Manitoba, Canada) and fellow co-author of the scientific paper commented:

“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs.”

Assistant Professor Brink added:

“Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions). Crocodile enamel is a bit thicker than dinosaur enamel, but not as thick as mammalian enamel. There are some mammal groups that do have exposed enamel, but their enamel is modified to withstand exposure.”

Theropod Teeth are Not Oversized

Previously, it had been suggested that the teeth of predatory dinosaurs were just too big to be covered by lips. This study challenges that view and suggests that theropod teeth were not atypically large. Even the huge, banana-shaped teeth of tyrannosaurs are proportionally similar in size to living predatory lizards when the actual skull size is considered. Therefore, the researchers reject the hypothesis that theropod teeth were too large to be covered by lips.

Model makers and figure manufacturers have created figures that reflect the current scientific debate about the presence or otherwise of lips in theropod dinosaurs. For example, Rebor recently introduced two new Tyrannosaurus rex figures “Kiss” being a lipped model, whereas the counterpart figure “Tusk” was lipless.

Rebor "Kiss" and Rebor "Tusk" T. rex figures.
Some model manufacturers have reflected the current scientific debate by producing replicas with lips as well as lipless forms such as the recent Rebor “Kiss” and “Tusk” figures.

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

Important Implications with Regards to Reconstructing Theropod Dinosaurs

This new study provides a new perspective on the “lips” versus “lipless” debate. It provides new insights into how scientists, artists and model makers reconstruct the soft tissues of dinosaurs and other prehistoric animals. This research provides information on how theropod dinosaurs fed, how they maintained their dental health as well as broader issues such as dinosaur ecology and evolution.

Dr Witton summarised the study stating:

“Some take the view that we’re clueless about the appearance of dinosaurs beyond basic features like the number of fingers and toes. But our study, and others like it, show that we have an increasingly good handle on many aspects of dinosaur appearance. Far from being clueless, we’re now at a point where we can say ‘oh, that doesn’t have lips? Or a certain type of scale or feather?’ Then that’s as realistic a depiction of that species as a tiger without stripes.”

The research team stress that their study does not say that no extinct animals had exposed teeth — some, like sabre-toothed carnivorous mammals, or marine reptiles and flying reptiles with extremely long, interlocking teeth, almost certainly did.

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

The scientific paper: “Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology” by Thomas M. Cullen, Derek W. Larson, Mark P. Witton, Diane Scott, Tea Maho, Kirstin S. Brink, David C. Evans and Robert Reisz published in the journal Science.

16 03, 2023

New Research Reveals Earliest Ichthyosaur Fossil Discovered to Date

By |2024-01-02T16:10:30+00:00March 16th, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

The earliest ichthyosaur fossil specimen discovered to date has been found on the Arctic island of Spitsbergen. The fossil represents a marine reptile that lived around 252 million years ago. The bones indicate that this animal was not a transitional form, but a fully adapted marine reptile.

Earliest ichthyosaur.
Reconstruction of the earliest ichthyosaur and the 250-million-year-old ecosystem found on Spitsbergen. Picture credit: Esther van Hulsen.

Picture credit: Esther van Hulsen

Ichthyosaur Evolution

The evolutionary history of the ichthyosaurs remains contentious. No transitional forms representing land-dwelling tetrapods adapting to a marine habit have been found. However, small, basal ichthyosauriforms are known from the Lower Triassic of China, and the fossils of at least one, primitive Early Triassic, dolphin-shaped member of the Ichthyopterygia has already been described from Spitsbergen (Grippia longirostris).

Thanks to the work of a joint team of Swedish and Norwegian palaeontologists a fresh perspective on the origins of the “fish lizards” is provided by these newly described fossil bones.

An Ichthyosaurus model
An Ichthyosaurus model, typical of the dolphin-like, streamlined forms that existed during the Early Jurassic. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

For models and replicas of typical ichthyosaurs and other marine reptiles: Wild Safari Prehistoric World Models.

The Ichthyopterygia (Ichthyosauria)

Ichthyosaurs were a highly successful, globally distributed group of marine reptiles. The evolved, a “dolphin-like” streamlined body and were active, nektonic predators surviving into the Late Cretaceous.

The first marine reptiles, such as the mesosaurs evolved during the Early Permian. The end-Permian mass extinction event devasted both terrestrial and marine faunas. The cataclysmic event was thought to have led to an evolutionary reset which permitted animals such as the Ichthyosauria to evolve, exploiting niches vacated after the extinction event.

Tetrapods (land-based vertebrates), invaded shallow coastal environments to take advantage of marine predator niches that were left vacant after the mass extinction event. Over millions of years, these early amphibious reptiles became more efficient at swimming and eventually modified their limbs into flippers, developed a ” dolphin-like” body plan, and started giving birth to live young (viviparity). With the evolution of viviparity, there was no need to come ashore in order to lay eggs, so the last ties these creatures had with a terrestrial existence was lost.

The newly described fossil material from Spitsbergen is helping to revise and re-write this previous hypothesis.

Fossil-bearing rocks on Spitsbergen
Fossil-bearing rocks on Spitsbergen that produced the earliest ichthyosaur remains. Picture credit: Benjamin Kear.

Picture credit: Benjamin Kear

Flower’s Valley Fossils

On western Spitsbergen a valley (Flower’s Valley), cuts deep into the surrounding mountains and provides access to Lower Triassic marine sediments, approximately 250 million years old. The rocks represent mud deposited at the bottom of an ancient sea and snow melt has gradually eroded the mudstone exposing rounded limestone boulders known as concretions. These objects are formed from limey sediments that coalesced around decomposing animal remains, subsequently preserving them in amazing, three-dimensional detail.

In 2014, the field team removed a number of concretions from the Flower’s Valley site. The rocks were taken back to the Natural History Museum at the University of Oslo for further study.

Scientists from The Museum of Evolution at Uppsala University have identified bony fish remains and bizarre “crocodile-like” amphibian bones, together with 11 articulated caudal vertebrae from an ichthyosaur.

Found in Rocks Thought to be Too Old for Ichthyosaur Fossils

Surprisingly, these tail bones occurred within rocks that were supposedly too old for ichthyosaurs. Also, the fossil bones do not represent a transitional form, but they show characteristics associated with geologically younger ichthyosaurs.

The vertebrae are identical to those of geologically much younger, larger-bodied ichthyosaurs, and even preserve internal bone microstructure showing adaptive hallmarks of fast growth, elevated metabolism and a fully oceanic lifestyle.

Fossil vertebrae from earliest ichthyosaur.
Computed tomography image and cross-section showing internal bone structure of vertebrae from the earliest ichthyosaur. Picture credit: Øyvind Hammer and Jørn Hurum.

Picture credit: Øyvind Hammer and Jørn Hurum

Dating the Surrounding Rock (Geochemical Testing)

Geochemical testing of the surrounding matrix dated the age of the fossils at approximately two million years after the end-Permian mass extinction. When the estimated timescale of marine reptile evolution is considered, this suggests the origins and early diversification of the Ichthyosauria took place during the Permian and prior to the Mesozoic Era.

These fossils suggest that the popular hypothesis of ichthyosaurs evolving to exploit niches vacated as a result of the end-Permian mass extinction is incorrect. Ichthyosaurs were present prior to the end of the Permian.

The discovery of the oldest ichthyosaur rewrites the popular vision of Age of Dinosaurs (Mesozoic Era), as the emergence timeframe of major reptile lineages. It now seems that at least some groups predated this landmark interval, with fossils of their most ancient ancestors still awaiting discovery in even older rocks on Spitsbergen and elsewhere in the world.

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

The scientific paper: “Earliest Triassic ichthyosaur fossils push back oceanic reptile origins” by Kear, B.P., Engelschiøn, V.S., Hammer, Ø., Roberts, A.J. and Hurum, J.H. published in Current Biology.

13 03, 2023

A Splendid Straight-shelled Nautiloid Pictured

By |2024-01-02T16:11:19+00:00March 13th, 2023|Adobe CS5, Everything Dinosaur Products, Main Page, Palaeontological articles, Photos, Teaching|0 Comments

The Silurian is a relatively short geological time period when compared to the other periods outlined in the geological time scale. The Silurian lasted around twenty-five million years (444 million years ago to approximately 419 million years ago). Although it was brief, in relative terms, during the Silurian the first land plants evolved and many invertebrate forms began to make the transition to a terrestrial habit. Life in the seas still dominated the Earth’s biota. One of the apex, marine predators was the straight-shelled nautiloid. Some of these orthocones evolved into giants.

straight-shelled nautiloid.
Everything Dinosaur and the straight-shelled nautiloid Orthoceras which was introduced into the CollectA range in 2020. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Straight-shelled Nautiloid

During the Silurian most of the nautiloid cephalopods had straight or slightly curved shells. The planispiral forms had yet to become common. The last straight-shelled forms (Orthocerida), probably died out during the Mesozoic. Most straight-shelled nautiloids became extinct at the end of the Triassic, but one fossil specimen collected in the Caucasus (Zhuravlevia insperata), indicates that one species persisted into the Early Cretaceous.

Orthocone/Orthoceras scale drawing.
An early scale drawing design for the Orthoceras/Orthocone fact sheet. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Zhuravlevia insperata

Described in 1994 by Larisa Doguzhaeva of the Swedish Museum of Natural History, based on a fragmentary orthocerid fossil, Zhuravlevia insperata is the geologically youngest straight-shelled orthocone known to science. The tiny fossil, just 1.3 cm long, with four chambers preserved, was found when Aptian-aged concretions from the Hokodz River Basin in the north-western Caucasus (Russia), were being split.

The orthocone fragment would be around 120 million years old.

CollectA introduced an Orthocone replica in 2020. The figure was added to the Age of Dinosaurs Popular range.

To view the invertebrate figures in the CollectA not-to-scale range including (whilst stocks last), Orthoceras: CollectA Age of Dinosaurs Popular Range.

5 03, 2023

New Study Suggests Some Theropod Dinosaurs Had a Propatagium

By |2024-01-02T16:48:15+00:00March 5th, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|1 Comment

New research suggests maniraptoran theropod dinosaurs possessed a propatagium. The propatagium (pronounced pro-pah-ta-gee-um), is a soft tissue structure that joins the wrists and shoulders of volant birds. It helps with the wing flapping motion and provides a leading edge to the wing. Without this structure, birds could not fly.

bird wing and the propatagium
The musculoskeletal structure of the wing of a pigeon. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

Propatagia in Maniraptoran Dinosaurs

If members of the Maniraptora, such as Therizinosaurus, Velociraptor, Oviraptor and troodontids had a propatagium on each arm, this would change how these dinosaurs are depicted. Many existing models and replicas would not be accurate and these figures would require updating.

Life reconstruction of dromaeosaurid dinosaur showing propatagium.
Life representation of a dromaeosaurid dinosaur showing the position of the propatagium. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

The Propatagium

Modern volant birds have a propatagium. A specialised wing structure, without which they would not be able to fly. The evolutionary origins of the propatagium remain uncertain, but new research led by scientists at the University of Tokyo (Japan), is helping to fill some of the gaps. By conducting a statistical analysis of the arm joints associated with the fossilised remains of some dinosaurs, the researchers have concluded that a propatagium was present in certain theropod dinosaurs on the dinosaur/bird evolutionary lineage.

Propatagia are also known in other volant vertebrates – the bats and pterosaurs. These structures are examples of convergent evolution. Anatomical traits arising as animals adapt in similar ways to similar selective pressures.

The propatagium in pterosaurs.
A Tropeognathus pterosaur model with the propatagia highlighted.

Birds Evolved from Dinosaurs

Most scientists agree that birds evolved from maniraptoran dinosaurs. It therefore seems appropriate to look for avian traits within the Dinosauria, such as the presence of feathers, strong but light bones, and inner ears that help with balance and spatial awareness.

The University of Tokyo’s Department of Earth and Planetary Science wanted to try to see if evidence for the propatagium could be found in the non-avian dinosaur fossil record. The propatagium contains a muscle which connects the wrist to the shoulder and the research team set about trying to find evidence for this soft tissue structure in the fossilised remains of maniraptoran dinosaurs.

Co-author of the paper, published in the journal “Zoological Letters”, Associate Professor Tatsuya Hirasawa explained:

“It [the propatagium] is not found in other vertebrates, and it’s also found to have disappeared or lost its function in flightless birds, one of the reasons we know it’s essential for flight. So, in order to understand how flight evolved in birds, we must know how the propatagium evolved. This is what prompted us to explore some distant ancestors of modern birds, theropod dinosaurs.”

Potential Propatagia in the Fossil Record.
Soft-tissue preservations of generally considered to be propatagia in non-avian theropods. A Microraptor gui (A), a member of the Dromaeosauridae (IVPP V 13352). Caudipteryx sp. B-D (IVPP V 12430), a member of the Oviraptorosauria clade. C and D represent the enlarged image and line drawing of the area of the white box in B, respectively. Broken lines in D indicate missing borders of the soft tissues. d1–3, digits 1–3; f, feather; g, gastralium; ppt, propatagium; r, radius; u, ulna. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

Studying Theropod Dinosaurs

Theropod dinosaurs such as Giganotosaurus, Tyrannosaurus rex and Velociraptor had arms, not wings, although some theropods such as the dromaeosaurid Microraptor were capable of flight. If the researchers could find evidence of early examples of the propatagium within non-avian dinosaurs, they would gain a better understanding of how some Dinosauria gradually transitioned from having arms to evolving wings.

Unfortunately, a soft tissue structure such as a propatagium would only be preserved in exceptional circumstances. Hard, mineralised parts of the body such as bones have a far greater fossilisation potential. Perhaps the bones of fossilised dinosaurs could provide a clue?

Co-author of the study, Yurika Uno (University of Tokyo) explained:

“The solution we came up with to assess the presence of a propatagium was to collect data about the angles of joints along the arm, or wing, of a dinosaur or bird.”

Studying Joint Angles

The presence or lack of a propatagium could be inferred by examining the angles of the joints in the arm in articulated fossil specimens. The way arm joints are articulated in fossils gives away the presence or absence of the propatagium structure. Thus the researchers could provide indirect evidence demonstrating the evolution of the avian wing structure.

The graduate student added:

“In modern birds, the wings cannot fully extend due to the propatagium, constraining the range of angles possible between connecting sections. If we could find a similarly specific set of angles between joints in dinosaur specimens, we can be fairly sure they too possessed a propatagium. And through quantitative analyses of the fossilised postures of birds and nondinosaurs, we found the tell-tale ranges of joint angles we hoped to.”

Joint angle in fossils suggests a propatagium may be present.
The researchers hypothesise that the way arm joints are articulated in fossils gives away the presence or absence of the propatagium. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

A Focus on the Maniraptora

The researchers postulate that the propatagium likely evolved in a group of dinosaurs known as the maniraptoran theropods. The Maniraptora clade is composed of coelurosaurian dinosaurs and is defined as including all birds and the non-avian dinosaurs that were more closely related to birds than they were to Ornithomimus velox.

Evolution of the propatagium.
The evolution of the propatagium in theropod dinosaurs. The researchers postulate that the propatagium evolved in maniraptoran theropods. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

Close examination of the fossilised remains of the oviraptorosaurian Caudipteryx and the winged dromaeosaurian Microraptor indicate the presence of propatagia. The researchers suggest that they have found evidence for the presence of a propatagium in dinosaurs that existed prior to the evolution of flight in the maniraptoran lineage.

Propatagium.
A propatagium hypothesised for the dromaeosaurid Deinonychus antirrhopus (left). The propatagium was present, while the wrist could be flexed to permit a grasping movement. The Early Cretaceous bird Sapeornis chaoyangensis (right) with the avian interlocking wing-folding system. Picture credit: ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY.

Why Did the Propatagium Evolve?

If maniraptoran dinosaurs had propatagia prior to the evolution of powered flight, then this raises an intriguing question. Why did the propatagium evolve? Why did these particular theropods evolve such a structure?

The University of Tokyo researchers are optimistic that by studying more fossils as well as embryonic development within extant vertebrates they might be able to provide some answers.

The team thinks some theropods might have evolved the propatagium not because of any pressure to learn to fly, as their forelimbs were made for grasping objects and not for flying. The propatagium originally had another purpose. It could be speculated that this “leading edge” of the arm evolved to help amplify visual intraspecific communication. Perhaps it evolved as a soft tissue structure used in display to demonstrate fitness for breeding and to win mates.

An enlarged surface area of the forelimb might have played a role in helping to shade eggs or perhaps play some other role in the brooding process.

Finding fossil evidence to support these suggestions is likely to prove difficult. However, if further studies demonstrate the presence of propatagia in the Maniraptora, it will change the way these types of dinosaurs are depicted.

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

The scientific paper “Origin of the propatagium in non-avian dinosaurs” by Yurika Uno and Tatsuya Hirasawa published in Zoological Letters

24 02, 2023

Rare Pinacosaurus Larynx Provides Insight on Dinosaur Vocalisation

By |2024-01-02T14:11:44+00:00February 24th, 2023|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A team of scientists have been studying a Pinacosaurus larynx and have concluded that this armoured dinosaur was probably capable of producing a variety of sounds and calls.

A juvenile specimen of Pinacosaurus (P. grangeri), specimen number IGM100/3186, preserves a hyoid and two laryngeal elements (cricoids and arytenoids) in almost life articulation. From these remains the researchers have concluded that just like crocodilians and birds, Pinacosaurus was capable of producing a range of vocalisations. The calls may have had several functions, to alert others of a predator approaching, to threaten a predator, to define territory or to search for a mate. The sounds made by this ornithischian dinosaur may have been related to courtship, or perhaps helped to call offspring to their side.

Pinacosaurus larynx study.
Skull in ventral view (a) photograph by Michael D’ Emic and edited by Junki Yoshida. A 3-D reconstruction of the skull, jaws and hyolaryngeal apparatus in left oblique view (b). Crico-aryteniod joint of right cricoid in medial view (c). The joint of left arytenoid in dorsolateral view (d). Arytenoid position in glottal opening (e) and glottal closing in anterior views (f). Arytenoid position in glottal opening (g) and glottal closing in dorsal views (h). Abbreviations: afa, articular facet for arytenoid; afc, articular facet for cricoid; ap, arytenoid process; atr, atlas rib; caj, crico-arytenoid joint; lcb, left ceratobranchial; lcr, left cricoid; md, mandible; pm, premaxilla; pd, predentary; rar, right arytenoid; rcb, right ceratobranchial; rcr, right cricoid. Scale bars equal 1 cm. Picture credit Yoshida et al.

Pinacosaurus grangeri

Pinacosaurus (P. grangeri) is regarded as a basal member of the Ankylosaurinae subfamily of ankylosaurs. It is known from copious fossil material, and it is one of the most extensively studied of all the Late Cretaceous Thyreophora. Fossils are known from the Mongolia and China (Djadokhta Formation and the geologically older Alagteeg Formation).

The compact and low-slung armoured dinosaur Pinacosaurus could have been adapted for digging.
A Pinacosaurus dinosaur model (PNSO). A study into their vocalisation has been published. Picture credit: Everything Dinosaur.

The image (above) shows a not-to-scale replica of Pinacosaurus (PNSO).

To view the range of PNSO dinosaur and prehistoric animal figures: PNSO Prehistoric Animal Models and Figures.

Pinacosaurus Larynx

In tetrapods the voice box (larynx) has several functions. It plays a role in respiration, protects the airway to prevent food items becoming lodged and it has a function in vocalisation. Fossil preservation of the larynx in archosaurs is extremely rare. The Pinacosaurus fossil material (IGM100/3186) represents the oldest voice box known to science. It provides scientists with an opportunity to better understand the evolution of the larynx in non-avian dinosaurs.

Pinacosaurus larynx in situ
The Pinacosaurus hyolaryngeal apparatus (tongue and voice box) in situ. A life reconstruction. Cricoid (purple), arytenoid (green), and ceratobranchial (blue) are depicted. Artwork by Tatsuya Shinmura.

Vocal Armoured Dinosaurs

Ossification of the cricoid and arytenoid is confirmed in Pinacosaurus, and it has been reported in Saichania, another Asian ankylosaurine. This configuration is also found in extant birds. The complex arrangement of the hyolaryngeal apparatus led the researchers to conclude that it did not simply function as a barrier to preventing food entering the trachea (airway protection). It was specialised for opening the glottis and possibly acting as a sound modifier.

The voice box of modern birds and crocodilians differs. In crocodiles and their close relatives it is the larynx that produces sounds. In birds, the larynx forms part of the vocal tract but they have a specialised organ (syrinx) located at the base of the trachea (wind pipe), that produces sounds.

Pinacosaurus – Shared Anatomical Characteristics

The researchers suggest that Pinacosaurus retained the same hyolaryngeal elements as found in crocodilians. However, Pinacosaurus shows many shared characters with birds in the arrangement and morphology of the larynx.

The authors of the scientific paper, which was published this month in “Communications Biology” (Junki Yoshida, Yoshitsugu Kobayashi and Mark Norell), propose that Pinacosaurus did not use the larynx as a sound source like non-avian reptiles. The larynx probably worked as a sound modifier as found in birds

Furthermore, the authors postulate that bird-like vocalisation likely appeared in non-avian dinosaurs before the evolution of the Aves (birds).

Article sourced from the open-access paper in Communications Biology.

The scientific paper: “An ankylosaur larynx provides insights for bird-like vocalization in non-avian dinosaurs” by Junki Yoshida, Yoshitsugu Kobayashi, Mark A. Norell published in Communications Biology.

21 02, 2023

Tracing Fascinating and Rare Dinosaur Footsteps

By |2024-01-02T14:19:23+00:00February 21st, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

It is widely accepted by palaeontologists that birds are descended from theropod dinosaurs. Their evolutionary lineage, the transition over time from the fast-running, agile, terrestrial Maniraptora to the birds we see today remains not fully understood. A new research project is being set up giving scientists the opportunity of tracing dinosaur footsteps to help them to better understand the evolutionary path of the avian dinosaurs.

A tridactyl theropod print.
A three-toed theropod footprint: Picture credit: Dr Peter Falkingham.

A £2.2 million GBP ($2.65 million USD) Research Project

A £2.2 million GBP ($2.65 million USD) research project funded by the European Research Council is being set up to permit scientists to study the evolution of the Dinosauria through their fossil tracks. The research project is to be led by Dr Peter Falkingham, a reader in vertebrate biology in the School of Biological and Environmental Sciences at Liverpool John Moores University.

Fossils of feathered dinosaurs and Mesozoic birds are known and have been extensively studied. Perhaps, one of the most intensively studied species in the entire fossil record is Archaeopteryx lithographica, a feathered theropod from the Upper Jurassic of southern Germany.

This five-year research programme, with its focus on studying theropod trace fossils, will provide a fresh perspective on the locomotion of the theropod/avian lineage.

Archaeopteryx fossil cast
Archaeopteryx fossil cast. Archaeopteryx is arguably one of the most extensively studied genera in the fossil record. This new research programme will focus on the locomotion of theropod dinosaurs. Picture credit: Everything Dinosaur.

Commenting on the scope of the study, Dr Falkingham explained:

“Fossil footprints are a direct record of motion in a way that skeletons can never be. I will use fossil footprints to explore the locomotor changes that took place as theropod dinosaurs evolved into birds.”

Creating a New Team

The plan is to establish a new team of post-doctoral scientists and technicians that will undertake advanced 3-D imaging of fossilised tracks and fossil skeletons. By combining trace fossils and body fossils in this way, the team hope to utilise kinematic and kinetic analyses to build an unprecedented view of footprint formation.

A simulated footprint (Guineafowl) mapped. Picture credit: Dr Peter Falkingham.

Tracing Dinosaur Footsteps

Limb motions of dinosaurs will be reconstructed using fossil tracks. Supercomputer simulations modelling every grain of a sediment responding to the indenting foot will be used to evaluate the reconstructed motions.

Dr Falkingham commented:

“These simulations will compute the forces occurring between foot and ground. These forces and motions will drive musculoskeletal biomechanical simulations that will shed light, not only on what the feet of dinosaurs were doing, but on how the whole limbs and even bodies of these enigmatic animals once moved. By sampling fossil tracks from around the world, spanning the 230 million years since theropods first appeared, this project will recover fossilised motions along the dinosaur-bird lineage.”

Mapping the locomotion of a footprint.
Mapping the locomotion of the avian lineage. Picture credit: Dr Peter Falkingham.

Extending our Knowledge About the Dinosaurs

Dr Falkingham added:

“The results should give us a unique view of locomotor evolution that cannot be recovered from bones alone.”

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

For further information and to follow the progress of this research project, visit the website of Dr Peter Falkingham: Dr Peter Falkingham.

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