Palaeontological articles

12 06, 2023

Amniote Success Not Down to Laying Eggs

By Mike|2023-06-13T06:27:57+01:00June 12th, 2023|Categories: Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos|0 Comments

The first tetrapods (land living animals) were amphibious. It had been thought that the development of an egg with a semi-permeable shell (amniote egg) was a fundamental step in the development of life on land. This adaptation meant that land animals did not have to return to water to breed and spawn. Freed from having to return to the water, early tetrapods could explore new environments and expand into new habitats.

However, a new paper written by researchers from Nanjing University (China) and the University of Bristol challenges this view of evolution.

The researchers conclude that the earliest reptiles, birds and mammals (Amniota), may have borne live young.

What is an Amniote?

Amniotes lay eggs that have a semi-permeable shell that protects the embryo from drying out. A tough, internal membrane called the amnion surrounds the growing embryo as well as the yolk, the food source. Development of the embryo in a shelled egg meant that for the first time in history, the tetrapods were no longer tied to water to breed. We as mammals are amniotes, along with the birds and reptiles.

Amniote egg diagram. — *The amniotic egg, showing the semipermeable shell and the extraembryonic membranes. Picture credit: M. J. Benton (University of Bristol).*

Studying Extinct and Extant Species

However, a study of 51 fossil species and 29 living species which could be categorised as oviparous (laying hard or soft-shelled eggs) or viviparous (giving birth to live young) suggests that the earliest reptiles, mammals and birds probably were capable of bearing live young.

The findings, published today in the academic journal “Nature Ecology & Evolution”, show that all the great evolutionary branches of the Amniota, the Mammalia, Lepidosauria (lizards and relatives), and the Archosauria (dinosaurs, crocodilians, birds) reveal viviparity and extended embryo retention in their ancestors.

To read an Everything Dinosaur blog post about research suggesting that an ancestor of the dinosaurs may have been a live-bearer: First Live Birth Evidence in Ancient Dinosaur Relative.

Extended Embryo Retention (EER)

Extended embryo retention (EER) occurs when the young are retained by the mother for a varying amount of time, likely depending on when conditions are best for survival. While the hard-shelled egg (amniote egg), has often been seen as one of the greatest innovations in evolution, this research implies it was extended embryo retention that gave this particular group of animals the ultimate protection.

Professor Michael Benton (School of Earth Sciences at the University of Bristol) explained:

“Before the amniotes, the first tetrapods to evolve limbs from fishy fins were broadly amphibious in habits. They had to live in or near water to feed and breed, as in modern amphibians such as frogs and salamanders.”

Professor Benton added:

“When the amniotes came on the scene 320 million years ago, they were able to break away from the water by evolving waterproof skin and other ways to control water loss. But the amniotic egg was the key. It was said to be a “private pond” in which the developing reptile was protected from drying out in the warm climates and enabled the Amniota to move away from the waterside and dominate terrestrial ecosystems.”

Challenging the Standard View About Amniote Egg Evolution

Project leader and corresponding author Professor Baoyu Jiang (Nanjing University) stated:

“This standard view has been challenged. Biologists had noticed many lizards and snakes display flexible reproductive strategy across oviparity and viviparity. Sometimes, closely related species show both behaviours, and it turns out that live-bearing lizards can flip back to laying eggs much more easily than had been assumed.”

Phylogeny of amniotes. — Phylogeny of amniotes, showing known reproduction mode and eggshell mineralization, and EER of 80 modern and extinct species, and the estimated ancestral states for all branching points. The dominant inferred state at the origin of amniotes is viviparity with extended embryo retention (EER). Picture credit: M.J. Benton, University of Bristol.

Many Marine Reptiles were Live-bearers

Co-author Dr Armin Elsler (University of Bristol) commented:

“Also, when we look at fossils, we find that many of them were live-bearers, including the Mesozoic marine reptiles like ichthyosaurs and plesiosaurs. Other fossils, including a choristodere from the Cretaceous of China, described here, show the to-and-fro between oviparity and viviparity happened in other groups, not just in lizards.”

CollectA Temnodontosaurus platyodon model. — *Detailed ichthyosaur figure. Temnodontosaurus platyodon.*

The picture (above) shows the CollectA Age of Dinosaurs Popular Temnodontosaurus model. The ichthyosaur is giving birth, demonstrating viviparity within the Ichthyosauria.

To view the range of CollectA not-to-scale models available from Everything Dinosaur: CollectA Age of Dinosaurs Popular Figures.

Delaying the Birth

In many types of extant vertebrate extended embryo retention (EER) is quite common. The developing young are retained by the mother for a lesser or greater span of time. The mother delays giving birth until conditions are most favourable to permit the survival of her offspring. The mother deliberately gives birth at the most propitious time.

Co-author of the paper, Dr Joseph Keating commented:

“EER is common and variable in lizards and snakes today. Their young can be released, either inside an egg or as little wrigglers, at different developmental stages, and there appears to be ecological advantages of EER, perhaps allowing the mothers to release their young when temperatures are warm enough and food supplies are rich.”

Computer generated model of the skeleton of a baby chorisodere. — *Skeleton of a baby choristodere, Ikechuosaurus, from the Early Cretaceous of China, found curled up inside the remnants of a parchment-shelled egg. Picture credit: Baoyu Jiang (Nanjing University).*

Profound Implications for our Understanding of Tetrapod Evolution

Professor Benton summarised the study:

“Our work, and that of many others in recent years, has consigned the classic ‘reptile egg’ model of the textbooks to the wastebasket. The first amniotes had evolved extended embryo retention rather than a hard-shelled egg to protect the developing embryo for a lesser or greater amount of time inside the mother, so birth could be delayed until environments become favourable.”

The professor implied that this study had profound implications for our understanding of tetrapod evolution. He added:

“Whether the first amniote babies were born in parchment eggs or as live, snapping little insect-eaters is unknown, but this adaptive parental protection gave them the advantage over spawning earlier tetrapods.”

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

The scientific paper: “Extended embryo retention and viviparity in the first amniotes” by Baoyu Jiang, Yiming He, Armin Elsler, Shengyu Wang, Joseph N. Keating, Junyi Song, Stuart L. Kearns and Michael J. Benton published in Nature Ecology and Evolution.

Visit the Everything Dinosaur website: Everything Dinosaur.

6 06, 2023

Several Different Spinosaurs in the Wealden Supergroup

By Mike|2023-06-09T08:34:21+01:00June 6th, 2023|Categories: Adobe CS5, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Researchers from the University of Southampton studying a partial spinosaurid tooth have concluded that several different spinosaurs inhabited southern England during the Early Cretaceous. The tooth consisting of a crown with a partial root is reputed to have come from East Sussex, most probably from Lower Cretaceous (Valanginian) exposures of the Hastings Group (part of the Wealden Supergroup). If this is the case, then this tooth is amongst the oldest spinosaurid fossils known from the UK.

Sorting the Stratigraphy

In common with many other isolated teeth found in strata associated with the Wealden Supergroup, it had been suggested that this tooth represented Baryonyx (B. walkeri). However, The Hastings Group underlies the Weald Clay Group from where the famous Baryonyx walkeri fossil material (NHMUK PV R9951) originates. Therefore, this fossil tooth is much older than the Baryonyx holotype material.

The fossil tooth could be around 138 million years old, much older than Baryonyx walkeri and therefore probably a different spinosaurid genus.

The Southampton University EvoPalaeoLab team carried out a series of tests on the isolated tooth. A statistical analysis confirmed that whilst the tooth was spinosaurid, it did not match any already described spinosaur species.

Project supervisor and co-author of the paper Dr Neil Gostling (University of Southampton explained:

“While we can’t formally identify a new species from one tooth, we can say this spinosaur tooth doesn’t match any of the existing species we know about. Given how many individual teeth exist in collections, this could be just the tip of the iceberg and it’s quite possible that Britain may have once teemed with a diverse range of these semi-aquatic, fish-eating dinosaurs.”

Many Different Spinosaurs

The Wealden Supergroup is famous for its dinosaur fossils. Baryonyx was discovered in a Surrey clay pit in 1983. Since then, isolated teeth from spinosaurids have tended to be assigned to this genus. Spinosaurids are a highly derived group of theropods. They evolved into piscivores and specialised in hunting and eating fish. Their jaws became elongated and crocodile-like and spinosaurids may have had their evolutionary origins in Europe.

CollectA Baryonyx dinosaur model. — *The CollectA new for 2020 Prehistoric Life Baryonyx dinosaur model. Picture credit: Everything Dinosaur.*

Picture credit: Everything Dinosaur

The model (above) is a CollectA Prehistoric Life Baryonyx figure.

To view this model range: CollectA Prehistoric Life Models and Figures.

Different Spinosaurs Represented by Fossils

Palaeontologists had suspected that there were several spinosaurid taxa represented by the Wealden Supergroup material. Spinosaurid teeth are known from formations that span much of the circa 25-million-year depositional history of the Wealden Supergroup, and recent works suggest that British spinosaurids were more taxonomically diverse than previously thought.

To read about two recently described, geologically younger spinosaurids from the Isle of Wight: Two New Spinosaurids from the Isle of Wight.

Lead author of the study, Chris Barker commented:

“We used a variety of techniques to identify this specimen, in order to test whether isolated spinosaur teeth could be referred to Baryonyx. The tooth did not group with Baryonyx in any of our data runs. It must belong to a different type of spinosaur.”

Distinct and Distantly Related Spinosaurids Lived in Southern England

The results demonstrate that distinct and distantly related spinosaur types lived in the region during the Early Cretaceous. This backs up research by the EvoPalaeoLab team, who argued in previous studies that the spinosaurs of southern England are more diverse than previously thought.

To read about the “White Rock” spinosaur announced in 2022, possibly one of the biggest theropods known from Europe: Super-sized Carnivorous Dinosaur from the Isle of Wight.

*Illustration of White Rock spinosaurid. Picture credit: University of Southampton/Anthony Hutchings.*

The Importance of Museum Collections

The study was able to take place as the researchers had access to a wealth of data as well as the fossil specimens themselves. It demonstrates the importance of maintaining access to fossil material for research purposes.

Dr Gostling explained:

“What this work highlights is the importance of keeping collections alive, and developing our understanding of them. Curators are essential to help us navigate the cupboards and displays, helping us to unpick the often-incomplete records – either never fully recorded, or lost to time. The diversity of palaeoenvironments is not always hidden in rocks, it is often waiting in a museum, its importance waiting to be rediscovered!”

Co-author Darren Naish added:

“Dinosaur teeth preserve numerous anatomical details, and we can use various analytical techniques to see how similar, or different, they are to other teeth. Our new study shows that previously unrecognised spinosaur species exist in poorly known sections of the Wealden’s history, and we hope that better remains will be discovered that improves our knowledge. Here’s another reminder that even well-studied places like southern England have the potential to yield new dinosaur species.”

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

The scientific paper: “Isolated tooth reveals hidden spinosaurid dinosaur diversity in the British Wealden Supergroup (Lower Cretaceous)” by Chris T. Barker, Darren Naish and Neil J. Gostling published in PeerJ.

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

26 05, 2023

Diapsid Fossil Teeth Provide New Information on Ecosystem Recovery

By Mike|2023-07-06T11:11:42+01:00May 26th, 2023|Categories: Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

A new study examining diapsid fossil teeth from Lower Triassic sediments in South Africa has provided further evidence of the recovery of terrestrial ecosystems after the end-Permian mass extinction event. The research highlights the growing diversity of archosauromorphs following the extinction of parareptiles and therapsids.

Diapsid fossil teeth study sees rise of Archosauromorpha in southern Africa. — Diapsid fossil teeth study sees rise of the Archosauromorpha in southern Africa. Temnospondyls (grey), archosauromorphs (monochrome), early mammals (yellow) and extinct therapsids (red). Picture credit: Everything Dinosaur.

For models and replicas of Permian and Triassic prehistoric animals: CollectA Deluxe Prehistoric Animal Figures.

Picture credit: Everything Dinosaur

Fossil Diapsid Teeth Study

The research team collected teeth from the Driefontein locality in Free State Province, South Africa. The strata represent Lower Triassic deposits (late Olenekian stage). The rocks are part of the Burgersdorp Formation and form part of the Karoo Basin, which provides an extensive geological record, crucially deposition that occurred before and after the end-Permian extinction event.

A total of 102 teeth were collected. The scientists identified 81 diapsid teeth with the remaining teeth classified as coming from temnospondyls. Analysis of the tooth morphology demonstrated that there was a greater diversity of archosauromorphs and other diapsids.

This research suggests that diapsids, especially archosauromorphs benefitted from the mass extinction event. They played an important role in the recovery of terrestrial ecosystems. Archosauromorphs filled many of the niches left vacant after the extinction of therapsids and anapsid reptiles.

Prehistoric life in South Africa — The prehistoric life of South Africa. The image shows the diverse flora and fauna that had evolved in South Africa by the Early Jurassic (Hettangian faunal stage). Archosaurs dominated terrestrial ecosystems but shared these habitats with other diapsids and early mammals. Picture credit: The Evolutionary Studies Institute (The University of Witwatersrand).

For an explanation of the fauna and flora depicted in the image (above): Celebrating the Rise of South African Dinosaurs.

The Rise of the Dinosauria

The fossil teeth from Driefontein provide palaeontologists with an important window into how terrestrial ecosystems recovered. The largest mass extinction recorded in the Phanerozoic occurred approximately 252 million years ago. The end-Permian mass extinction event devastated both marine and terrestrial ecosystems. The Karoo Basin may yield further evidence to help palaeontologists to better understand how life bounced back from the mass extinction event. It may also help scientists to understand how the Archosauromorpha were able to gain an evolutionary advantage over other tetrapods. This may have ultimately helped the Dinosauria and their close relatives to dominate terrestrial habitats.

The scientific paper: “A diverse diapsid tooth assemblage from the Early Triassic (Driefontein locality, South Africa) records the recovery of diapsids following the end-Permian mass extinction” by Devin K. Hoffman, John P. Hancox and Sterling J. Nesbitt published in Plos One.

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

6 05, 2023

Rare Fossil Sturgeon Scute Discovered in Morocco

By Mike|2024-01-02T20:22:49+00:00May 6th, 2023|Categories: Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Geology, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

The discovery of a fossil sturgeon scute demonstrates that these “royal fish” were present in North Africa during the Late Cretaceous. The single, fossil scute is the first ever sturgeon fossil to have been found in Africa. The scute is a bony plate embedded into the sturgeon’s skin. Scutes provided a form of dermal armour that evolved to help protect these very ancient fish.

Sturgeon fossil scute. — *A digital photo of the sturgeon scute (also called buckler) specimen. Picture credit: University of Portsmouth.*

A Significant Fossil Discovery

The sturgeon (there are more than two dozen extant species), belongs to the Acipenseriformes Order, which probably originated in the Late Triassic. Sturgeon fossils which are very similar to extant species, are known from Upper Cretaceous strata. Historically, they are associated with cooler waters of the Northern Hemisphere. The specimen was discovered by Professor David Martill (University of Portsmouth). It proves that these magnificent fish were present in Africa.

Sturgeons were more widespread in the Cretaceous than previously thought.

A European sturgeon. — *An extant European sturgeon. Picture credit: University of Portsmouth.*

Professor Martill was exploring a well-known Moroccan fossil site during a field trip last November. He spotted a row of bony plates (bucklers) on a piece of rock and instinctively recognised the fossils represented the scutes from a sturgeon.

Discussing this significant fossil find, the Professor commented:

“It was a surprising discovery because all sturgeon species have been exclusively found in the Northern Hemisphere in the past. They’ve been located in North America, Europe, Russian Asia, Chinese Asia, but never in South America, Australia, Africa or India, which are the land masses that made up Gondwana, a supercontinent that existed around 336 million years ago and began breaking up around 150 million years ago.”

Extant sturgeon diagram. — *A drawing showing an extant sturgeon in lateral view. The different scutes are highlighted. Picture credit: University of Portsmouth.*

A “Royal Fish”

The sturgeon has long been prized for its meat and for its roe (eggs). The roe is commonly referred to as caviar. King Edward II of England declared that all sturgeon from the waters of Wales and England belong to the monarch. This declaration was made in the early 14th century. Since then, these fish have been regarded as “royal fish”.

Sadly, due to overfishing and pollution, many species of extant sturgeon are close to extinction.

Commenting on his African fossil discovery Professor Martill stated:

“Russian beluga caviar is one of the most expensive in the world. Little did we know that at one time an extremely rare African sturgeon could have been a source of this delicacy!”

Fossil Sturgeon Scute

Sturgeon are thought of as being “living fossils”, for they seem to have remained relatively unchanged since the time of Tyrannosaurus rex and Triceratops. Records from the 18th and 19th centuries indicate specimens reaching more than seven metres in length and weighing over 1.5 tonnes, but fish of this size are exceedingly rare today.

Professor Martill added:

“The very first sturgeons appear in the fossil record in the Late Triassic period in China. But the oldest true sturgeon ever discovered is probably a specimen in the Steve Etches collection from Dorset’s Jurassic Coast in England, which is mentioned in a book Steve and I wrote about fossils in the Kimmeridge Clay Formation.”

The discovery of a sturgeon fossil in Morocco complicates models of the geographical distribution of these fish during the Late Cretaceous.

A fossil sturgeon scute indicates that these ancient fish lived in Africa. — *A map of the continents at the end of the Cretaceous (66 million years ago). Sturgeon fossil localities are marked by solid black circles. Picture credit: University of Portsmouth*

The fossil specimen is now in the collection of the University King Hassan II, Casablanca.

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

The scientific paper: “A sturgeon (Actinopterygii, Acipenseriformes) from the Upper Cretaceous of Africa” by David M. Martill published in Cretaceous Research.

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

25 04, 2023

Mapping Marine Reptiles Thanks to New Research

By Mike|2024-01-02T16:51:12+00:00April 25th, 2023|Categories: Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Whilst the Dinosauria dominated terrestrial environments during the Mesozoic the seas and oceans of the world were home to a diverse assemblage of marine reptiles. Many different types of marine reptile evolved, and the diverse swimming techniques employed by these ancient animals have been revealed in a recently published scientific paper.

The swimming secrets of Mesozoic marine reptiles have been decoded thanks to a research team from the University of Bristol.

Levy the Eurhinosaurus. — A replica of the ichthyosaur Eurhinosaurus (PNSO). During the Mesozoic, many different types of marine reptile evolved. Scientists from the University of Bristol have unlocked the swimming secrets of ancient marine reptiles.

The image (above) shows a replica of an Eurhinosaurus. An ichthyosaur (Leptonectidae family) that lived during the Early Jurassic (approximately 180 million years ago).

The model is from the PNSO range of figures: PNSO Age of Dinosaurs.

Marine Reptile Diversity During the Mesozoic

During the Mesozoic, which lasted from approximately 252 million years ago to the end-Cretaceous mass extinction event around 66 million years ago, many different types of marine reptile evolved. There were placodonts, turtles, the first ichthyosaurs and nothosaurs during the Triassic and these were replaced by marine crocodiles, derived ichthyosaurs, long-necked plesiosaurs and pliosaurs. During the Cretaceous the mosasaurs evolved.

In the new paper, published in the academic journal “Palaeontology”, the research team report on the use of cutting-edge statistical methods used to undertake a substantial quantitative study. This research, the first of its kind, provides a fresh perspective on the locomotion of Mesozoic marine reptiles.

Examining 125 Skeletons

In total, 125 marine reptile skeletons were studied. The research team mapped the changes in swimming styles within the different lineages over time. There was no explosive radiation at the beginning of the Triassic, but a gradual diversification of swimming styles. This diversity peaked during the Cretaceous.

Marine reptile diversity and swimmng styles. — Marine reptiles from the Mesozoic Era evolved a great diversity of body forms and sizes. Changes in their body and limb anatomy throughout evolution are associated with swimming adaptations. The variety of locomotory modes in Mesozoic marine reptiles is illustrated by (bottom-to-top) an early mosasauroid, a placodont, a plesiosaur and a fish-shaped ichthyosaur. Picture credit: Dr Susana Gutarra.

Dr Susana Gutarra (School of Earth Sciences at the University of Bristol), lead author of the paper commented:

“Changes in anatomy in land-to-sea transitions are intimately linked to the evolution of swimming. For example, sea lions’ flippers have relatively short forearm and large hands, very different from the walking legs of their ancestors. The rich fossil record of Mesozoic marine reptiles provided great opportunity to study these transitions at a large scale.”

The End-Permian Mass Extinction Event

At the end of the Permian, the Earth experienced a catastrophic mass extinction event. Life on Earth was devastated. It has been estimated that 50% of all marine families and over 80% of all marine genera died out (Raup and Sepkoski).

Remarkably, marine environments recovered relatively quickly. Various groups of reptiles became aquatic hunters.

To read an article from 2010 that documents a remarkable fossil site in China that provides evidence of how marine food webs recovered from the end-Permian mass extinction event: Ancient Ecosystem Revealed.

To test the validity of the statistical analysis, measurements from extant aquatic animals were included in the study.

Co-author Beatrice Heighton (University of Bristol), explained:

“We included measurements from living aquatic animals, such as otters, seals and turtles, of which we know their swimming behaviour. This is very important to provide a functional reference for the ancient species, with unknown swimming modes.”

Liopleurodon marine reptile is studied — Palaeobiologist Dr Susana Gutarra taking measurements from a very complete specimen of Liopleurodon, a pliosaur from the Middle-Late Jurassic of Germany (Museum of Palaeontology in Tübingen). Picture credit: Dr Susana Gutarra.

A Gradual Diversity of Swimming Styles

Co-author Dr Tom Stubbs (University of Bristol) added:

After this devastating event, there was a gradual diversification of locomotory modes, which contrasts with the rapid radiation described previously for feeding strategies. This is fascinating because it suggests a ‘head-first’ pattern of evolution in certain lineages.”

The scientific paper sheds light into the swimming styles of specific groups of marine reptile.

Dr Ben Moon (University of Bristol) explained the significance of this study, stating:

“Ichthyosaurs were highly specialised for aquatic locomotion from very early in their evolution. This includes their close relatives, the hupehsuchians, which had a morphology unlike any other known aquatic tetrapod. Further, we see overlap between mosasaurs and ichthyosaurs, which is indicative that mosasaurs evolved a swimming mode by oscillating flukes, different from the eel-like body undulation suggested in the past.”

To read a recent Everything Dinosaur article about the discovery of the earliest ichthyosaur known to science: Earliest Ichthyosaur Fossil Discovered to Date.

Temnodontosaurus fossil on display. — An almost 8m-long specimen of Temnodontosaurus, an ichthyosaur from the Early Jurassic of Germany (State Museum of Natural History of Stuttgart, Germany), is one of the fossils included in this study. Picture credit: Dr Susana Gutarra.

Dr Moon of Bristol University’s School of Earth Science went onto add:

“In contrast, we don’t find evidence of convergence between ichthyosaurs and metriorhynchids (the highly aquatic crocodyliform thalattosuchians). This group retained quite primitive-looking hindlimbs, which seems incompatible with swimming by fluke oscillation.”

Examining the Evolution of Size

This comprehensive study also examined the evolution of size, a feature related to locomotion, animal physiology and ocean productivity.

The University of Bristol’s Professor Mike Benton, a co-author of the research paper commented:

“We know that transition to life in water is usually accompanied by an increase in body mass, as seen in cetaceans, and one of our previous studies shows that large sizes benefit aquatic animals in reducing the mass-specific costs of drag. Thus, it was essential to explore this trait in the wider ensemble of Mesozoic marine reptiles.”

To read an article about the discovery of the earliest known plesiosaur: The First Triassic Plesiosaur.

Dr Gutarra explained that body mass follows a similar trend to the diversification of locomotory modes. The widest spread of body size also occurred in the Cretaceous. This confirms a strong correlation between the evolution of diverse swimming styles and changes in body mass.

Dr Gutarra added:

“The rate of increase and the maximum limits to body size seems to vary a lot between groups. This is a fascinating observation. We need to explore further what factors influence and limit the increase in body mass in each group.”

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

The scientific paper: “The locomotor ecomorphology of Mesozoic marine reptiles” by Susana Gutarra, Thomas L. Stubbs, Benjamin C. Moon, Beatrice H. Heighton and Michael J. Benton published in Palaeontology.

13 04, 2023

Near-complete Titanosaur Skull Found in Queensland

By Mike|2023-04-12T18:52:08+01:00April 13th, 2023|Categories: Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A virtually complete titanosaur skull has been found in Queensland. The fossil discovery is Australia’s most complete sauropod skull found to date. It supports the hypothesis that Australian sauropods originated in South America. The titanosaur skull has been assigned to Diamantinasaurus matildae.

Titanosaur skull fossils. — *A view of the Diamantinasaurus skull bones in approximate life position: Picture credit: Australian Age of Dinosaurs.*

Diamantinasaurus matildae

Australian Age of Dinosaurs Museum researchers in collaboration with Curtin University (Perth) despatched a media release announcing the discovery of the stunning sauropod skull. The fossil specimen, nicknamed “Ann” was excavated in 2018 at a dig site located at Elderslie Station, near Winton (Queensland).

A view of the dig site "Ann" the location of the discovery of titanosaur skull fossils. — *Field team members working at the “Ann” dig site. Picture credit: Australian Age of Dinosaurs.*

The fossil specimen is believed to be between 98-95 million years old (Cenomanian faunal stage of the Late Cretaceous). It is the fourth specimen of Diamantinasaurus matildae to have been discovered by Australian Age of Dinosaurs Museum staff.

Studying the Skull

Research on the titanosaur skull was led by Museum Research Associate Dr Stephen Poropat, a
Postdoctoral Research Fellow at Curtin University.

Dr Poropat stated:

“This skull gives us a rare glimpse into the anatomy of this enormous sauropod that lived in northeast Australia almost 100 million years ago.”

Examining the Queensland dinosaur fossils. — Dr Stephen Poropat (left) and right, Dr Phil Mannion (University College London) examining the “Ann” site fossil material including the Diamantinasaurus skull bones, the Oliver scapula and vertebra two. Picture credit: Australian Age of Dinosaurs.

Implications for Titanosaur Evolution

The researchers identified similarities between “Ann” and the skull of another titanosaur Sarmientosaurus musacchioi. S. musacchioi fossils come from southern Argentina, from rocks which are roughly contemporaneous with the Winton Formation strata. The braincases of these two titanosaurs were similar, along with the dentition (teeth). Similar anatomical characteristics were also identified in the quadratojugal (a bone from the back of the skull near the posterior of the lower jaw).

Dr Poropat commented that their findings support previous theories that sauropods were using Antarctica as a migratory pathway between South America and Australia between 100 and 95 million years ago.

The doctor added:

“Our research suggests that Diamantinasaurus was one of the most ‘primitive’ titanosaurs. Gaining a better understanding of this species might explain why titanosaurs were so successful, across so much of the world, right until the end of the Age of Dinosaurs.”

A Life Reconstruction of the titanosaur head (Diamantinasaurus matildae). — *A life reconstruction of the titanosaur Diamantinasaurus. Picture credit: Australian Age of Dinosaurs.*

For models and replicas of titanosaurs and other sauropods: CollectA Deluxe Prehistoric Animal Models.

Titanosaur Skull Links Australian Dinosaurs to Antarctica and South America

At the beginning of the Late Cretaceous (100 to 95 million years ago), the Earth was much warmer than it is today. Antarctica which was located approximately where it is today, was ice free. Australia was much further south and closely associated with the Antarctic landmass. The huge conifer forests of Antarctica might have been an attractive habitat for migratory sauropods. The similarities between “Ann” and Sarmientosaurus skull matieral lends weight to the theory that titanosaurs used Antarctica as a pathway to Australia.

The Diamantinasaurus skull fossils are currently on display at the Australian Age of Dinosaurs Museum.

Everything Dinosaur acknowledges the assistance of a media release from the Australian Age of Dinosaurs Museum in the compilation of this article.

The scientific paper: “A nearly complete skull of the sauropod dinosaur Diamantinasaurus matildae from the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs” by Stephen F. Poropat, Philip D. Mannion, Samantha L. Rigby, Ruairidh J. Duncan, Adele H. Pentland, Joseph J. Bevitt, Trish Sloan and David A. Elliott published by Royal Society Open Science.

12 04, 2023

Reduction in Mammal Skull Bones led to Evolutionary Success

By Mike|2023-04-12T14:37:19+01:00April 12th, 2023|Categories: 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 Mike|2024-01-02T20:05:59+00:00April 9th, 2023|Categories: 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).

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 Mike|2024-01-02T20:09:29+00:00April 3rd, 2023|Categories: 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.

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 Mike|2023-05-08T12:35:00+01:00April 1st, 2023|Categories: 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.

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.”

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.