Recently published temnospondyl research suggests that adopting a generalist feeding ecology helped these ancient amphibians to survive the end-Permian mass extinction event.  The study published this week in the journal “Royal Society Open Science”, concludes temnospondyl’s success lay in their generalist feeding ecology. The temnospondyls consist of an extinct clade comprising around three hundred known species.  They evolved in the Early Carboniferous and persisted until the Early Cretaceous.  This represents a timespan of around two hundred and thirty million years.  Temnospondyls were traditionally classified as amphibians, although their taxonomic affinity with the Amphibia remains controversial.  It is more technically correct to refer to these vertebrates as anamniote tetrapods.

A dorsal view of the CollectA Deluxe Koolasuchus a late surviving temnospondyl from the Early Cretaceous of Australia. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The photograph (above) shows a dorsal view of Koolasuchus cleelandi model. It is the youngest temnospondyl described to date.  Fragmentary fossils are thought to be around 125-120 million years old (Barremian – Aptian faunal stages of the Cretaceous).  The model is from the CollectA Deluxe range of scale prehistoric animal figures.

To view this range of prehistoric animal models: CollectA Deluxe Prehistoric Life Models.

A Mystery of the end-Permian Mass Extinction Event

One of the mysteries of the end-Permian mass extinction was the subsequent success of temnospondyls. This catastrophic global event occurred approximately 252 million years ago.  It was the largest extinction event in the Phanerozoic, marked by the loss of as many as 90% of all species.  Although many types of temnospondyl died out, following this mass extinction temnospondyls diversified rapidly during the Early Triassic.  Numerous lineages arose.  These lineages continued, although with diminishing diversity throughout the remainder of the Triassic.  A few taxa survived into the Jurassic before the temnospondyls are thought to have finally become extinct during the Early Cretaceous.

Researchers led by scientists from the University of Bristol propose that these animals thrived after the mass extinction event by feeding on freshwater prey that evaded terrestrial predators.

By adopting a generalist feeding ecology, these predators could consume a wide variety of prey despite all the environmental changes going on during the Triassic. A broader examination of Triassic ecosystems also indicates that the freshwater habitats temnospondyls preferred provided them with a relatively stable variety of food resources.  This allowed them to thrive while strictly terrestrial predators made do with meagre, unstable resource availability on land.

A Mastodonsaurus rises out of the depths to ambush a small, archiosauriform (Jaxtasuchus). Picture credit: Mark Witton.

Picture credit: Mark Witton

Mastodonsaurus (see image above), is known from the Middle Triassic of Europe.  It was one of the largest temnospondyls, with an estimated body length of more than five metres.

Lead author of the study Aamir Mehmood (University of Bristol School of Biological Sciences), commented:

“One of the great mysteries has been the survival and flourishing of a major group of amphibians called the temnospondyls.  These were predatory animals that fed on fishes and other prey, but were primarily linked to the water, just like modern amphibians such as frogs and salamanders. We know that climates then were hot, and especially so after the extinction event. How could these water-loving animals have been so successful?”

The Triassic “Tropical Dead Zone”

The Early Triassic was a time of repeated volcanic activity leading to long phases of global warming, aridification, reductions in atmospheric oxygen, acid rain and widespread wildfires, creating conditions so hostile that the tropics became devoid of animal life. This “tropical dead zone” drastically impacted the distributions of both marine and terrestrial organisms.

Co-author Dr Suresh Singh said:

“We collected data on a hundred temnospondyls that lived throughout the Triassic and wanted to look at how their ecologies changed. We measured their body sizes and features of the skulls and teeth that tell us about function.”

Dr Armin Elsler another co-author of the temnospondyl research paper added:

“Much to our surprise, we found that they did not change much through the crisis. The temnospondyls showed the same range of body sizes as in the Permian, some of them small and feeding on insects, and others larger. These larger forms included long-snouted animals that trapped fishes and broad-snouted generalist feeders. What was unusual though was how their diversity of body sizes and functional variety expanded about five million years after the crisis and then dropped back.”

Due to the intense global warming of the first five million years of the Triassic, there is evidence that life on land and in the sea moved away from the tropics to avoid the heat.

Professor Mike Benton (University of Bristol) explained:

“Our work shows that the temnospondyls, unexpectedly, were able to cross the tropical dead zone. Fossils are known from South Africa and Australia in the south, as well as North America, Europe and Russia in the north. The temnospondyls must have been able to criss-cross the tropical zone during cooler episodes.”

An exhibit featuring a reconstruction of the skeleton of the giant Permian temnospondyl Eyrops. New research suggests that temnospondyl’s success during the Early Triassic lay in their generalist feeding ecology. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The Decline of the Temnospondyls

Aamir summarised the team’s findings stating:

“Their burst of success in the Early Triassic was not followed up. They coped with the hot conditions probably by having a low requirement for food, by being able to eat most prey animals, and by hiding in sparse water bodies. But when the ancestors of dinosaurs and of mammals began to diversify in the Middle Triassic, the temnospondyls began their long decline.”

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

The scientific paper: “The ecology and geography of temnospondyl recovery after the Permian – Triassic mass extinction” by Aamir Mehmood, Dr Suresh Singh, Dr Armin Elsler and Professor Michael Benton published in Royal Society Open Science.

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

A jumbled set of bones first spotted on a beach on the southern portion of the Isle of Skye in 1973 have been identified as a probable ornithopod.  The Elgol dinosaur fossil is Scotland’s earliest recorded dinosaur fossil discovery.  A research team led by Dr Elsa Panciroli (NERC Independent Research Fellow at National Museums Scotland), visited the site in 2018 and began the challenging process of extracting the fossil specimen from the surrounding boulders.

A specialist Canadian company was invited to supervise the extraction of the rare fossil.  Once the difficult task of releasing the fossil slab was completed, it was carefully loaded onto an inflatable dingy and piloted safely back to port by a local crew from Elgol’s Bella Jane Boat Trips.  The researchers were so worried about the fossil block sinking that they tied several buoys to it in the hope that if the boat should capsize, the rare fossil could still be located.

Lead author Dr Elsa Panciroli with the Elgol dinosaur fossil. The jumbled bones have proved difficult to identify. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

The Dinosaur Fossil Record of Scotland

The fossil record of dinosaurs in Scotland mostly comprises isolated highly fragmentary bones from the Great Estuarine Group in the Inner Hebrides.  These sediments were deposited in the Middle Jurassic (Bajocian–Bathonian faunal stage).  The Elgol dinosaur fossil is estimated to be around 166 million years old. It is the first and most complete partial dinosaur skeleton currently known from Scotland. The material has been assigned a specimen number (NMS G.2023.19.1).

After manual preparation, the scientists were able to identify part of the spine, ribs and elements from the hips (a partial ilium).  Unfortunately, micro-CT scanning failed to help with fossil identification.  However, the team are confident that the material does represent a dinosaur, an ornithischian and most likely an ornithopod.  If it does prove to be an ornithopod, then it would be one of the world’s oldest ornithopod body fossils described to date.

The Elgol dinosaur fossil has been interpreted to represent an early ornithopod. Picture credit: Maija Karala.

Picture credit: Maija Karala

Lead author of the study, Dr Elsa Panciroli stated:

“This was a really challenging extraction, in fact we’d previously felt was too difficult to collect the fossil, but I thought it was really important to study it. I was able to persuade the team to give it a try. It took a lot of hard work from a lot of people, but we did it: finally we can confirm and publish Scotland’s first recorded and most complete dinosaur, and that makes it all worthwhile”.

Cerapodan or Ornithopod Dinosaur

The ornithischian (bird-hipped) clade of the Dinosauria has been subdivided into several groups.  Although the exact taxonomy remains undetermined, most palaeontologists distinguish two main groups. Firstly, there is the Thyreophora which comprises the armoured dinosaurs. In addition, there is the Cerapoda which can be further divided into the Ornithopoda and the Marginocephalia (ceratopsids and pachycephalosaurs).

The partial ilium and a histological analysis of fossil bone led the team to conclude that NMS G.2023.19.1 was definitely ornithischian and probably an early ornithopod. Ornithopods were much more common in the Early and Late Cretaceous.  Famous ornithopods such as Iguanodon, Hypsilophodon and Mantellisaurus are associated with Lower Cretaceous deposits.

A Mantellisaurus scale drawing.  An illustration of an Early Cretaceous ornithopod.  Picture credit: Everything Dinosaur

Picture credit: Everything Dinosaur

The ornithopod illustration (above) is based on the CollectA Age of Dinosaurs Mantellisaurus model that was introduced in 2018.  This was the same year when the fossil was removed from its difficult to access location.

To view the range of CollectA Age of Dinosaur figures, including many ornithopods: CollectA Age of Dinosaurs Figures.

Late Cretaceous ornithopods were extremely successful.  Hadrosaurs became the dominant herbivores in many ecosystems.  The Hadrosauridae family (duck-billed dinosaurs) had a global distribution. Some of these dinosaurs were enormous.  For example, Shantungosaurus from the Late Cretaceous of China reached lengths in excess of fourteen metres.

The Elgol Dinosaur Fossil

The Elgol fossils suggest an animal about the size of a pony.  Histological analysis concluded that the animal was at least eight years of age when it died. The new description of the Elgol dinosaur is published in the Earth and Environmental Science Transactions of the Royal Society of Edinburgh. If the fossil material does represent an ornithischian, as tentatively suggested from the partial ilium and histological sectioning, it represents the geologically youngest known occurrence in Scotland, and first from the Kilmaluag Formation.  This adds to the diversity of dinosaurs known from the Middle Jurassic of the Isle of Skye.

To read an article about the types of dinosaurs that lived in this part of the world during the Middle Jurassic: Tracks of Middle Jurassic Dinosaurs.

A close-up view of the 166-million-year-old Elgol dinosaur fossil. Dr Elsa Panciroli carefully examines the fossil material. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

Co-author of the study, Dr Stig Walsh (National Museums Scotland) said:

“This is a wonderful addition to the rapidly growing set of Jurassic finds from the Isle of Skye which are enabling us to learn more and more about the rich ecosystem of the time. We’ve known there were dinosaurs there for a while, most obviously from the famous footprints at An Corran, Brother’s Point and Duntulm and from individual bones, but it’s exciting to see a more complete, if still partial, skeleton. We’re delighted to add it to the other amazing finds now in the National Collection”.

Other recent Jurassic discoveries from Skye include the description of adult and juvenile mammals of the same species, Krusatodon, which revealed that these mammals grew more slowly than mammals today, and possibly one of the world’s largest Jurassic pterosaurs, Dearc sgiathanach.

To read Everything Dinosaur’s article about the Krusatodon fossils: Providing an Insight into Krusatodon Ontogeny.

To read about the discovery of D. sgiathanach: Fantastic Pterosaur from the Isle of Skye.

More Dinosaur Fossils?

Fellow author Professor Susie Maidment of the London Natural History Museum and the University of Birmingham, added:

“The Elgol dinosaur was a challenge to collect, and has proven perhaps an even bigger challenge to identify. Some aspects of the bones indicate that the specimen may be an ornithopod, a group of plant-eating dinosaurs that are best known from the Cretaceous. This specimen, however, would already have been a fossil by the time that the better-known ornithopods like Iguanodon and Hypsilophodon were walking the Earth. Recent research on the fossils of Elgol has revealed a diverse ecosystem of extraordinarily preserved Middle Jurassic animals, and I’m sure there are more exciting discoveries to come.”

The other authors on the paper were Professor Roger Benson (American Museum of Natural History), Professor Richard Butler (University of Birmingham), Brett Crawford (Research Casting International – RCI), Matt Fear (RCI), Dr Nick Fraser (National Museums Scotland) and Dr Gregory Funston (Royal Ontario Museum).

With the description of the Elgol dinosaur fossil, the significance of the Isle of Skye is once again emphasised.  Furthermore, it demonstrates the importance of this part of Scotland in terms of learning more about the dinosaur biota from the Middle Jurassic.

Everything Dinosaur acknowledges the assistance of a media release downloaded from National Museums Scotland.

The scientific paper: “The first and most complete dinosaur skeleton from the Middle Jurassic of Scotland” by Elsa Panciroli, Gregory F. Funston, Susannah C. R. Maidment, Richard J. Butler, Roger B. J. Benson, Brett L. Crawford, Matt Fair, Nicholas C. Fraser and Stig Walsh published in the Earth and Environmental Science Transactions of The Royal Society of Edinburgh.

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