Evidence of Recovery after End Permian Extinction Event
A very strange member of a little known group of ancient marine reptiles has been formally described by a joint team of American and Chinese scientists. The new genus described as “platypus-like” is a Hupehsuchian, part of a group of Early Triassic diapsid reptiles, that may have been ancestral to the much better known Ichthyosaurs. The fossil has been named Eohupehsuchus brevicollis, the name means “early short-necked crocodile of Hubei Province” and it was excavated from strata laid down around 248 million years ago (Olenikian faunal stage), as the world recovered from the “Great Permian Dying”, a mass extinction event that is believed to have wiped out around 95% of all the species on the planet.
Fossils associated with Hupehsuchia have been found in two counties within Hubei Province (eastern, central China). The Order Hupehsuchia was named after the alternative name for Hubei Province (hupeh), E. brevicollis is unlike any other known member of the Hupehsuchia as it possessed a short neck, with only six cervical vertebrae. Other Hupehsuchians had much longer necks, with at least ten neck bones. The forty centimetre long specimen is believed to represent an adult animal, it is somewhat smaller than the better known Nanchangosaurus (fossils dated from the Middle Triassic) and it lacked teeth. Analysis of the skull and jaws indicate that this little reptile probably had a beak like a duck (hence the platypus analogy), it paddled its way through the shallow sea using its strong limbs. The bones are thickened and heavy, indicating some adaptation to a marine environment. Heavy bones would have helped these animals dive, although it did possess extensive dermal armour, perhaps a remnant of its terrestrial ancestry. Scientists are unsure as to whether the extensive armoured scales evolved in the Hupehsuchia after they adapted to a marine existence or whether these tough scales evolved in this group’s reptile ancestors, which lived on land.
The Fossilised Remains of E. brevicollis
Picture Credit: PLOS One
One of the lead authors of the scientific paper, published this week in the on line journal PLOS One, Professor Ryosuke Motani (University of California Davis), commented:
“Although it’s a very different animal, it had a skull and beak like a duck without teeth, a very heavily built body with thick bones and paddles to swim through the water. The details are different, but the general body design looks similar to a platypus.”
With at least four genera identified as Hupehsuchia, researchers are beginning to piece together how marine ecosystems recovered after the Permian mass extinction. Intriguingly, this specimen indicates that there were most probably large vertebrate predators in the habitat 248 million years ago. The left forelimb is incomplete, with several bones missing and those present are broken. This has been interpreted as a bite from a larger predator that could only have occurred pre-burial. This little reptile may have been attacked by a predator and escaped only to perish and to be buried a short while after.
This fossil find adds to the growing body of evidence that suggests a rapid radiation and diversification of vertebrates after the mass extinction event.
The University of California researchers have been prominent in the research into Lower Triassic marine reptiles from China. Back in November, Everything Dinosaur published an article on a fossil of a basal Ichthyosaur that had been studied by this team. Unlike, Eohupehsuchus which comes from Hubei Province, the basal Ichthyosaur fossil was found in the neighbouring province of Anhui (to the east of Hubei Province).
To read more about the Anhui basal Ichthyosaur: Tracing the Origins of the Ichthyosaurs