Sclerocormus parviceps: Ancient Ichthyosaur-Like Reptile Discovered
Sclerocormus parviceps. Image credit: Da-Yong Jiang.
Ichthyosaurs were a successful group of marine animals that flourished in the world’s oceans of the Mesozoic era.
Most of them looked a little bit like today’s dolphins. They were well adapted to feed in water, with a long, narrow, and often graceful snout armed with teeth.
But the new species, scientifically named Sclerocormus parviceps, is a strange anomaly in the ichthyosaur world.
It measured about 5.3 feet (1.6 m) long, including a 3 foot (92 cm) long tail. It had a short snout and, instead of a tail with triangular flukes (think of a fish’s tail-fins), it had a long, whip-like tail without big fins at the end.
And while many ichthyosaurs had conical teeth for catching prey, the new species was toothless and instead seems to have used its short snout to create pressure and suck up food like a syringe.
“Sclerocormus parviceps tells us that ichthyosauriforms evolved and diversified rapidly at the end of the Lower Triassic period,” said Dr. Olivier Rieppel of the Field Museum.
“We don’t have many marine reptile fossils from this period, so this specimen is important because it suggests that there’s diversity that hasn’t been uncovered yet.”
The way Sclerocormus parviceps evolved into such a different form so quickly sheds light on how evolution actually works.
“It has been considered that early Mesozoic marine reptiles evolved slowly in the Early Triassic after the end-Permian mass extinction, contrary to the fast radiation of most metazoans during the same time interval,” Dr. Rieppel and co-authors said.
“The present and other recent discoveries of Early Triassic marine reptiles indicate that the diversification of Triassic marine reptiles was not a single phase of unbroken increase in diversity. There were at least two waves of marine reptile diversification, separated by a taxonomic bottleneck near the Early-Middle Triassic boundary.”
Marine reptiles like Sclerocormus parviceps that lived just after the end-Permian mass extinction also reveal how life responds to huge environmental pressures.
“We’re in a mass extinction right now, not one caused by volcanoes or meteorites, but by humans,” Dr. Rieppel said.
“So while the extinction 250 million years ago won’t tell us how to solve what’s going on today, it does bear on the evolutionary theory at work.”
Research describing the new species is published online in the journal Scientific Reports.
Da-Yong Jiang et al. 2016. A large aberrant stem ichthyosauriform indicating early rise and demise of ichthyosauromorphs in the wake of the end-Permian extinction. Sci. Rep. 6, 26232; doi: 10.1038/srep26232
Triassic Reptile from Tanzania Finally Gets Scientific Name: Mandasuchus tanyauchen
An international team of paleontologists from the Natural History Museum, London, the University of Birmingham and Virginia Tech has formally given an ancient carnivorous reptile a name, over several decades since its fossils were found in Tanzania. The formal species description of Mandasuchus tanyauchen is published in a special memoir of the Journal of Vertebrate Paleontology.
A paleoartist’s reconstruction of Mandasuchus tanyauchen. Image credit: Mark Witton / Trustees of the Natural History Museum, London.
A cousin of modern-day crocodiles, Mandasuchus tanyauchen was an archosaur — the lineage of reptiles that include dinosaurs, crocodiles and birds.
The ancient reptile lived around 245 million years ago (Triassic period) and grew up to 10 feet (3 m) in length.
The fossilized remains of Mandasuchus tanyauchen were first discovered in the 1930s as part of a major paleontological expedition to East Africa, which included work on a geological formation in Tanzania called the Manda Beds.
The fossils in these beds date from the Middle Triassic epoch. This was a time when the archosaurs began their rise to dominance.
English paleontologist Alan Charig proposed the name Mandasuchus for this species in the 1950s, when he studied the Tanzanian fossils as part of his PhD thesis. Charig continued his career in paleontology, but never completed his work on this reptile.
In recent years, new expeditions to Tanzania have found additional fossils, which have remained in Tanzania.
Combined with the older discoveries, these are shedding light on exciting topics such as early dinosaur evolution.
“Studies like these highlight the important role that museums play as storehouses of information of the natural world,” said senior author Professor Paul Barrett, a paleontologist in the Department of Earth Sciences at the Natural History Museum, London.
“Although it took decades to complete this work, the specimens remained safe and accessible in our collections and now form the basis of this amazing new species.”
Richard J. Butler et al. 2018. Mandasuchus tanyauchen, gen. et sp. nov., a pseudosuchian archosaur from the Manda Beds (Middle Triassic) of Tanzania; pp. 96–121 in C. A. Sidor and S. J. Nesbitt (eds.), Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia. Society of Vertebrate Paleontology Memoir 17. Journal of Vertebrate Paleontology 37 (6); doi: 10.1080/02724634.2017.1343728
