Euchambersia mirabilis was Probably Venomous

Detailed scans of the skull of the stem-mammal Euchambersia mirabilis supports a theory first proposed by the enigmatic Baron Franz Nopcsa ninety years ago, that this Late Permian creature was venomous.  Scientists at the University of Witwatersrand (South Africa), concur with the Baron’s idea that this half-metre-long therapsid reptile known from the famous Karoo Supergroup, represents the earliest known venomous terrestrial vertebrate.

An Illustration of the Late Permian Therapsid Euchambersia mirabilis

An illustration of the Late Permian therapsid Euchambersia.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

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Euchambersia mirabilis and Baron Nopcsa

Baron Nopcsa was an Austro-Hungarian aristocrat who discovered and identified a number of dinosaurs and other prehistoric animals around the world.  In 1933, during a trip to South Africa, he looked at the remains of a therapsid found a couple of years earlier by Robert Broom, the fossil was identified as a distant ancestor of today’s Mammalia.  Nopcsa stated that the fossils probably represented an animal with a deadly bite.

Nopcsa declared that this was probably the earliest venomous species ever recorded.  However, his theory couldn’t be confirmed or disproved because venom and venom glands don’t fossilise.  A study of the skull and the upper jaw (maxilla) had shown that E. mirabilis had a huge, deep maxillary fossa (a hollow), associated with a ridged canine.  To the Baron, this implied that Euchambersia possessed a specialised gland situated inside the maxillary fossa that was capable secreting venom down the ridged canine tooth into victims.

CT Scanning Technology Provides Support for Nopcsa’s Theory

A team of researchers from the Johannesburg-based university set out to scan the known fossil skulls of Euchambersia and to create detailed three-dimensional images.  It seems that Baron Nopcsa was right, the 21st century technology supports the idea that the 255-million-year-old Euchambersia is indeed, the earliest example of a venomous terrestrial vertebrate known to science.

Some extant mammals produce venom, for example, the bizarre Australian Duck-billed platypus (a monotreme), but also amongst placentals there are venomous mammals too.  With a stem-mammal probably being venomous, it puts forward a tantalising idea that in the past, all early mammal forms may have had venom, but as the synapsid lineage that was to give rise to modern mammals evolved, so the venom producing glands were lost.

Known from Only Two Fossil Specimens

The fossils that Baron Nopcsa studied back in 1933, represent a species that is only known from one other set of fossils.  Both specimens were discovered in the same area, just a few metres apart close to the town of Colesberg (Northern Cape Province of South Africa).  The second specimen was not found until 1966.  One specimen is housed in the collection of the Natural History Museum London, the other is at the Evolutionary Studies Institute in Johannesburg.

A Closer View of One of the Euchambersia Skulls Used in the Study

A closer look at one of the Euchambersia mirabilis fossil skulls.

Picture credit: University of Witwatersrand

CT Scans Provide Evidence

Each specimen was CT scanned at its respective institute, and the London data was sent to the researchers at the University of Witwatersrand.  The three-dimensional models that the images were able to provide gave the scientists the opportunity to explore in great detail the internal structure of the upper jaw.

CT Scans Revealed New Details of Euchambersia Skull and Jaw Anatomy

CT scans showing various views of the Euchambersia skull material.

Picture credit: PLOS One/University Witwatersrand

Lead author of the report, published in PLOS One, Dr Julien Benoit commented:

“We found that a wide, deep and circular fossa to accommodate a venom gland was present on the upper jaw and was connected to the canine and the mouth by a fine network of bony grooves and canals.  Moreover, we discovered previously undescribed teeth hidden in the vicinity of the bones and rock, two incisors with preserved crowns and a pair of large canines, that all had a sharp ridge.   Such a ridged dentition would have helped the injection of venom inside a prey.”

Dr Julien Benoit Holding One of the Skulls that was Scanned

Dr Julien Benoit holds one of the Euchambersia fossil skulls.

Picture credit: University of Witwatersrand

Identifying Anatomical Adaptations in Euchambersia mirabilis

It seems that Euchambersia had anatomical adaptations which were compatible with venom production.  The confirmation of the Baron’s theory strengthens the belief that pre-mammalian therapsids were very diverse and occupied a wide range of niches within Late Permian and Early Triassic ecosystems.

These ancient creatures, distantly related to our own species, diversified as herbivores and carnivores, large and small, burrowing and ground-dwelling species.  As the earliest venomous species and a representative of this early wave of pioneering species, Euchambersia directly reflects the extraordinary adaptive capabilities of these mammalian forerunners.

The scientific paper: “Reappraisal of the Envenoming Capacity of Euchambersia mirabilis (Therapsida, Therocephalia) using μCT-scanning Techniques,” published in the on line journal PLOS One.

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

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American Fossil Site Shows Diverse Range of Marine Fauna Post Permian Extinction Event

A team of international scientists writing in the on line academic journal “Science Advances” have published details of a complex and diverse Early Triassic marine ecosystem that contradicts the commonly held view that life on Earth was slow to recover from the catastrophic End Permian mass extinction.

An Early Triassic Marine Ecosystem

The fossils of around thirty different species of marine creature have been excavated from shales and limestone near to the city of Paris in Idaho (USA).  Four sites in total have been unearthed in Bear Lake County and they represent a marine ecosystem that existed just 1.3 million years after the Permian mass extinction event, the most devastating extinction event recorded in the whole of the Phanerozoic Eon (visible life).

Just 1.3 Million Years After the End Permian Extinction Event a Surprisingly Diverse Marine Ecosystem Thrived

The Early Triassic marine fauna of the Paris Basin (Idaho).

Picture credit: Jorge Gonzalez

A Dynamic Early Triassic Marine Ecosystem

Ammonite and conodont fossils have been used as biostratigraphical markers and the site has been dated to the middle Olenekian faunal stage of the Early Triassic, approximately 250.6 million years ago.  The fossils demonstrate that life, at least in some parts of the world bounced back remarkably quickly after the End Permian extinction event that is believed to have wiped out around 95% of life on the planet.

Lead author of the paper, palaeontologist Arnaud Brayard of the University of Burgundy-Franche-Comté (France) stated:

“Our discovery was totally unexpected.”

The Location of the Paris Basin Site (Modern and Mesozoic)

The Bear Lake fossil site location (modern and during the Early Mesozoic).

Picture credit: Romano et al (Science Advances)

The picture above shows (A) the site of the Paris Basin in the context of the geography of the United States, (B) a close up of the location of the dig sites (Paris biota) identified by the researchers.  Picture (C) shows the approximate position of the Paris Basin during the Early Triassic.  The site was very close to the equator during the Early Triassic.

Surprising Fossil Discoveries

The diverse ecosystem consisted of ammonites and other cephalopods, sponges, brachipods and bivalves along with echinoids (sea urchins) crinoids, crustaceans and several vertebrates including marine reptiles, sharks more than two metres long and bony fish.

The Paris Basin ecosystem, included some unexpected creatures.  There was a type of sponge previously believed to have gone extinct 200 million years earlier (leptomitid sponges), and a squid-like group (gladius-bearing coleoids), previously thought not to have evolved until the Late Triassic.  In addition, the scientists report the finding of bones that could represent the earliest-known ichthyosaur or at least a direct ancestor of an ichthyosaur.

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Several other fossils display anatomical characteristics that were thought to have evolved much later (for example, echinoderms), indicating an early and rapid post-Permian/Triassic boundary diversification for these groups as well as previously unknown phylogenetical links between Palaeozoic and Mesozoic taxa.

Brayard added:

“The Early Triassic is a complex and highly disturbed Epoch, but certainly not a devastated one as commonly assumed, and this epoch has not yet yielded up all its secrets.”

Some of the Fossils Representing the Remarkable and Diverse Early Triassic Marine Fauna

Examples of the multitude of fossil from the Paris Basin.

Picture credit: A. Brayard, Université Bourgogne Franche-Comté (A to G); T. Saucède, Université Bourgogne Franche-Comté (H); and B. Thuy, Natural History Museum Luxembourg (I).

Analysing the Fossils

The photograph above shows a selection of fossils from the Paris Basin (A) a sponge fossil and ammonites, (B) leptomitid sponge and tiny brachiopods, (C) an ancient lobster, (D) a new genus of thylacocephalan crustacean and (E) shrimp fossil.  Picture (F) shows another shrimp fossil depicted under ultraviolet light. Whilst picture (G) shows a Gladius-bearing coleoid, a type of cephalopod that previously, had been thought to have evolved some fifty million years later.  A crinoid stem is shown in picture (H) and (I) depicts the remains of a Brittlestar.  Scale bars equal five millimetres for all the pictures, except for photograph (B) – scale bar one centimetre.

The researchers conclude that the Paris Biota highlights the key evolutionary position of Early Triassic fossil ecosystems in the transition from the Palaeozoic to the modern marine evolutionary fauna at the dawn of the Mesozoic era.

 The scientific paper: “Unexpected Early Triassic Marine Ecosystem and the Rise of the Modern Evolutionary Fauna”, published in the journal Science Advances.

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Dinocephalosaurus – The Only Known Viviparous Archosauromorph

The first ever evidence of live birth in an animal group previously thought to lay eggs exclusively has been discovered by an international team of scientists, including a palaeontologist from the University of Bristol.  Writing in the academic journal “Nature Communications”, the researchers report upon the identification of a potential embryo inside the mother, a specimen of the long-necked archosauromorph Dinocephalosaurus (D. orientalis).

Dinocephalosaurus orientalis

Live birth (viviparity), is known in a number of extant reptiles, especially members of the Order Squamata, wherein a number of species of snakes and lizard “hatch” inside their mother and emerge without a shelled egg.  However, this is the first time that live birth has been recorded in the Archosauromorpha, the infraclass of diapsid tetrapods that includes birds, crocodiles and dinosaurs.

An Illustration of the Long-Necked Marine Reptile Dinocephalosaurus (Location of Embryo Shown in Drawing)

Dinocephalosaurus illustration. The red circle shows the approximate location of the embryo.

Picture credit: Dinghua Yang with additional annotation by Everything Dinosaur

The picture above shows an illustration of the marine reptile Dinocephalosaurus.  The approximate position of the embryo inside the mother is indicated by the red circle.

Egg Laying in Tetrapods

Egg laying is regarded by many scientists as a more primitive form of reproduction, seen at the base of reptiles, within the amphibious anamniotes and the ancestors of terrestrial vertebrates (fish).  The fossil was found in 2008, at a quarry famous for marine fossils located in Yunnan Province (southern China).

Dinocephalosaurus was a long-necked, piscivore that flourished in warm, tropical, shallow sea that once covered much of China.  Its fossils have been dated to the Middle Triassic.  Dinocephalosaurus has been classified as a member of the Tanystropheidae family of archosauromorphs but how closely related it was to the better known Tanystropheus remains open to debate.

An Illustration of a Typical Member of the Tanystropheidae (Tanystropheus)

A drawing of the bizarre Triassic reptile Tanystropheus.

Picture credit: Everything Dinosaur

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The Tanystropheidae Family

The Tanystropheidae family flourished during the Triassic and they were quite ecologically diverse.  Most of the genera are associated with Tethys Ocean coastline deposits, although several species are associated with strata laid down inland.  The scientists discovered the embryo inside the rib cage of the mother, and it faces forward making it less likely to have been consumed.  Swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat.  Furthermore, the small reptile inside the mother is an example of the same species.

Lead study author, Professor Jun Liu from Hefei University of Technology (China), stated:

“We were so excited when we first saw this embryonic specimen several years ago, but we were not sure if the embryonic specimen is the last lunch of the mother or its unborn baby.  Upon further preparation and closer inspection, we realised that something unusual has been discovered.  Further evolutionary analysis reveals the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and the Pterosauria among others, and pushes back evidence of reproductive biology in the group by fifty million years.”

The Fossilised Remains Showing a Close View of the Embryo in the Rib Cage

Dinocephalosaurus illustration. The red circle shows the approximate location of the embryo.

Picture credit: Jun Lu

Implications of the Dinocephalosaurus Fossil for Other Members of the Archosauromorpha

Evolutionary analysis shows that this instance of live birth was also associated with genetic sex determination.  Co-author of the scientific paper, Professor Chris Organ, (Montana State University) commented:

“Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest.  We identified that Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds.”

The researchers conclude that this specimen from Yunnan Province rewrites our understanding of the evolution of reproductive systems.  Perhaps, some distant descendants of these reptiles also retained this reproductive strategy, with other archosauromorph members using live birth rather than external egg laying.  Maybe some dinosaurs were viviparous.

Studying the Dinocephalosaurus Embryo

The embryo measures around fifty centimetres in length, when fully grown Dinocephalosaurus measured over three metres long (although about half of its entire body length was made up of that super-sized neck).  It is possible, that the scientists have drawn the wrong conclusion.  The animal, if it was a baby Dinocephalosaurus and not the fossil specimen’s last meal that “went down the wrong way”, may have been in an egg and the eggshell that once surrounded the embryo was not preserved during the fossilisation process.

That explanation cannot be completely ruled out, but Professor Benton explained that the embryo’s bones were very well developed, whilst all living archosauromorphs lay eggs very early in embryonic development.

Furthermore, the team suggest that Dinocephalosaurus’s long neck and other features of its anatomy indicate it could not have manoeuvred easily out of the water, meaning a reproductive strategy like that of turtles, which lay eggs on land before returning to the water, was probably not an option.

Professor Mike Benton (School of Earth Sciences, Bristol University), another co-author of the paper said:

“The analysis of the evolutionary position of the new specimens shows there is no fundamental reason why archosauromorphs could not have evolved live birth.  This combination of live birth and genotypic sex determination seems to have been necessary for animals such as Dinocephalosaurus to become aquatic.  It’s great to see such an important step forward in our understanding of the evolution of a major group coming from a chance fossil find in a Chinese field.”

A Need to Look Closely at Other Fossils

Professor Benton added that since we now know that no fundamental biological barrier to live births exists in the Archosauromorpha, palaeontologists would be “looking very closely” at other fossils.  He suggested one target would be a group of aquatic crocodile relatives, whose mode of reproduction was not well known.

This piece of work is part of wider collaborations between palaeontologists in China, the United States, the UK and Australia.

The scientific paper: “Live birth in an Archosauromorph Reptile” by J. Liu, C. L. Organ, M. J. Benton, M. C. Brandley and J. C. Aitchison published in Nature Communications

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

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