Our thanks to fossil collector and dinosaur model fan Robert who sent Everything Dinosaur a coelacanth fossil to add to our collection. The specimen is an example of Whiteia woodwardi, which is known from Triassic strata. The genus was both geographically and temporally widespread. Whiteia fossils are known from Madagascar (where this specimen comes from), as well as Indonesia and British Columbia (Canada).
The Canadian and Madagascan fossils are associated with Lower Triassic strata, whereas the Indonesian material (Whiteia oishii) is associated with Upper Triassic deposits (Norian faunal stage).
The Coelacanth fossil (Whiteia woodwardi) from the Lower Triassic of Madagascar. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
A Coelacanth Fossil
The fish remains were preserved inside a concretion. When this nodule was split open the fossilised fish was revealed. The skull is present (to the left of the photograph), and scales can be observed. The impression of a fleshy pectoral fin can be seen.
Coelacanths are an ancient group of lobe-finned fish (Sarcopterygii). It is thought that these fish first evolved in the Early Devonian, around 410 million years ago. Two species are known today, in the genus Latimeria.
The beautifully painted and very blue Mojo Fun Coelacanth replica.
The picture (above) shows a model of a Coelacanth. This figure is from the Mojo Fun model series.
A spokesperson from Everything Dinosaur commented:
“We would like to thank Robert for his most generous gift. We did not have a Coelacanth specimen in our fossil collection. Thanks to Robert’s generosity we have this wonderful specimen, and we are looking forward to putting it into one of our fossil display cabinets.”
The spokesperson added:
“The Coelacanth fossil can be used in some of our outreach work. We highlight threats to animals today such as global warming and climate change and the Coelacanth, with its long fossil record helps us to explain about extinction and deep geological time.”
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.
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).
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 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.”
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.”
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.”
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.
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.
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).
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.”
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 Diamantinasaurus. Picture credit: Australian Age of Dinosaurs.
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.
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.
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.”
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.
An illustration of Lufengosaurus. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
The image (above) is a drawing of the Early Jurassic sauropodomorph Lufengosaurus.
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.
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.
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.
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.
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.
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.
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.
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.”
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.
Today, March 18th, we at Everything Dinosaur commemorate the life of the American palaeontologist Othniel Charles Marsh. The eminent professor and president of the prestigious National Academy of Sciences passed away on this day in 1899.
Othniel Charles Marsh
Regarded as one of the great pioneers of American palaeontology he described more than a dozen new genera of dinosaurs, based on fossils excavated from the Western United States. He was responsible for naming and scientifically describing many of the most famous of all the Dinosauria. Brontosaurus, Apatosaurus, Triceratops and Stegosaurus were all named by Marsh.
A view of the anterior of “Sophie” the Stegosaurus stenops specimen on display at the London Natural History Museum. Othniel Charles Marsh named and described the first Stegosaurus species in 1877. Picture credit: Everything Dinosaur.
Theropod Dinosaurs, Prehistoric Birds and Pterosaurs
Marsh also named and described the theropod dinosaur Allosaurus (1878), named and described toothed-birds, early horses and studied the first pterosaur fossils known from the USA.
For all his academic and scientific achievements, perhaps O. C. Marsh is best remembered for his bitter rivalry with his fellow American scientist Edward Drinker Cope. A rivalry that became known as the “Bone Wars”.
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.
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, typical of the dolphin-like, streamlined forms that existed during the Early Jurassic. Picture credit: Everything Dinosaur.
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 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.
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.
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.
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.
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.
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.”
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.”
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.
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.
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
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.
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).
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).
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.
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.
