Oldest Known Metriorhynchid Super Predator from the Middle Jurassic

Some fragmentary bones, including jaw material and teeth unearthed when a Peterborough clay pit (Peterborough in Cambridgeshire, England) was explored by the famous amateur palaeontologist Alfred Leeds, have been identified as a new genus of marine crocodile super predator.  The fossils which include isolated teeth, elements of the mandible and some post cranial material, first excavated by Leeds as he examined Oxford Clay strata exposed at the Fletton clay brick pits close to Peterborough have been assigned to the species Tyrannoneustes lythrodectikos representing the oldest, large metriorhynchid crocodilian known to date.

Tyrannoneustes lythrodectikos

Although the actual size of this prehistoric, marine predator is hard to calculate accurately, studies of the teeth and estimates of the gape of the mouth indicate that this reptile was probably an apex predator and the fossil material helps palaeontologists to better understand the evolutionary path taken by marine crocodiles as they competed with other types of marine reptiles in the warm, tropical seas that covered much of England during the Jurassic geological period.

The fossils were discovered around the turn of the 20th century, they were first formally listed in 1919 forming part of the vertebrate fossil collection at the Hunterian Museum at the University of Glasgow.  The material remained relatively undisturbed until a team of palaeontologists led by researchers from the Department of Geosciences at the University of Edinburgh had the opportunity to examine the fossil specimens in detail.  The team concluded that the fossils represented a new species of giant, marine crocodile that swam in the Middle Jurassic seas around 165 – 163 million years ago.

An Artist’s Impression of the New Genus of Marine Crocodile

Fearsome marine crocodile Tyrannoneustes.

Picture credit: Press Association/University of Edinburgh

Middle Jurassic Marine Crocodile

The newly assigned species, helps scientists to piece together a picture of the marine ecosystem during the Middle Jurassic, a time when ichthyosaurs and plesiosaurs shared this environment with the crocodilians.

The Metriorhynchidae are a large family of marine crocodiles that seem to have had their hey day in the Late Jurassic.  Fossils of these predatory reptiles have been found in Switzerland, France, England, Germany and also in South America.   These animals ranged in size from around two metres in length to apex predators that may have reached lengths in excess of seven metres or more.  Dr Mark Young of the School of Geosciences at the University of Edinburgh has studied a number of apex Metriorhynchidae crocodilians, monsters like Dakosaurus and the much larger Plesiosuchus for example.  However, such large members of the Metriorhynchidae are associated with more recent Upper Jurassic strata whereas, the fossils ascribed to Tyrannoneustes date from earlier Middle Jurassic deposits.

To view replicas and models of Jurassic prehistoric animals: PNSO Age of Dinosaurs Figures.

This new research, which has just been published in the academic publication “The Journal of Systematic Palaeontology” allows scientists to partially fill a gap in the evolution and radiation of the Metriorhynchidae as these creatures evolved into top predators from smaller genera that specialised in catching fish and cephalopods.

A Formidable Hunter

The wide gape of the mouth and the teeth capable of shearing flesh and bone would have made this marine crocodile a formidable hunter, the fearsome nature of this beast is reflected in the scientific name Tyrannoneustes lythrodectikos, which means “blood-biting tyrant swimmer”.

Dr Mark Young, one of the authors of this study commented that:

“It was satisfying to be able to classify a specimen that has been unexamined for more than one hundred years, and doubly so to find that this discovery improves our understanding of the evolution of marine reptiles.”

The research team are confident that this fossil material represents a transitional stage in metriorhynchid evolution between smaller crocodiles feeding on small prey and other, later forms that filled an ecological niche in a similar way to modern-day Orcas.

To read an earlier article into the research work on marine crocodiles carried out by scientists at the University of Edinburgh: Marine Crocodiles More Like Killer Whales Than Crocodiles.

Intriguingly, other isolated teeth and a partial humerus found in Oxford Clay deposits suggest that at least one other genus of large, marine crocodile may have been present in the tropical seas around 165 million years ago.

New Dinosaur Discovery Challenges the Theory of Bird Evolution

A single, thirty-centimetre-long fossil of a dinosaur from China is helping palaeontologists to understand a little more about the complex evolutionary path between the  Dinosauria and Aves (birds), the fossil, representing a new genus of basal troodontid has been named Eosinopteryx brevipenna.  This dinosaur lived in a swampy environment with plenty of tree cover.  The discovery of this fossil increases the known diversity of small-bodied, feathered dinosaurs that lived during the Middle to Late Jurassic and shows that a number of different taxa of feathered, mainly cursorial dinosaurs occupied different niches in dinosaur dominated ecosystems suggesting that the evolution of flight and ultimately the Class Aves is much more complex than was thought some twenty years ago.

Eosinopteryx brevipenna

Archaeopteryx (A. lithographica) may be regarded as a transitional fossil between the Dinosauria and true birds, but it seems that the Late Jurassic feathered dinosaur from finely grained limestone deposits of Solnhofen in Germany may only represent one of a number of dinosaur lineages that had feathers.

This new fossil discovery comes from the Tiaojishan Formation of western Liaoning, a Province in China.  The strata of the Tiaojishan Formation has been dated to around 165 -155 million years ago (Early Bathonian to Mid Oxfordian faunal stage).   The specimen represents an adult or possibly a sub-adult specimen and an analysis of the well-preserved fossil shows that this little dinosaur had a short snout, quite large eyes, small arms covered in short feathers and toes suited to running (cursorial lifestyle).

E. brevipenna had fewer feathers on its tail and lower legs, these adaptations would have made it easier to run.  It can be speculated that this feathered dinosaur probably hunted insects, lizards and small mammals in the undergrowth.  An anatomical study of the bone structure of the arms of this reptile suggest that it could not fly, the feathers may have aided the animal jumping from logs and other obstacles, perhaps acting as mini air brakes to help control landing.  The genus name Eosinopteryx means “Early Chinese Feather”.

The Fossil Specimen (Eosinopteryx brevipenna)

Helping to unravel the evolution of flight.

Picture credit: Macmillan Publishing

One of the co-authors of the scientific paper (published in the academic journal “Nature Communications”), Dr Gareth Dyke from the University of Southampton commented that:

“This discovery sheds further doubt on the theory that the famous fossil Archaeopteryx – or “first bird” as it is sometimes referred to – was pivotal in the evolution of modern bird.”

Bird Evolution

The team’s findings suggest that the origin of flight was much more complex than was thought twenty years ago, with there being a lot of evidence to suggest that there were a number of feathered, cursorial dinosaur genera present in the Middle to Late Jurassic.  Interestingly, the rocks of the western part of Liaoning Province have provided a substantial number of pterosaur fossils. In this part of China towards the end of the Jurassic there were a lot of reptiles that were very accomplished fliers – members of the Pterosauria.

One such genus is Darwinopterus (named after the naturalist Charles Darwin).  Known from around forty fossil specimens including one that showed an egg about to be laid but still present in the animal’s body, this pterosaur genus shows important anatomical characteristics that suggests it may be a transitional form from the primitive rhamphorhynchoid pterosaurs to the more advanced, shorter-tailed pterodactyloid pterosaurs.

To read an article on Darwinopterus: Pterosaur Transitional Fossil – Darwinopterus.

An Illustration of Eosinopteryx brevipenna

On the way to flight

Picture credit: Royal Belgian Institute of Natural Sciences

Liaoning Province may be famous for its feathered fossils representing creatures from the Early Cretaceous but it also seems that the older strata of this part of China can lay claim to a number of feathered dinosaur fossils too.

To view models and replicas of early birds and feathered dinosaurs: PNSO Age of Dinosaurs Models and Replicas.