The world had just been through an incredible disaster in the form of the Permian Extinction. Ninety-five percent of all life on the planet had been wiped out in the cataclysm, including marine ecosystems. Yet the sheer weirdness of Atopodentatus shows us just how quickly life was rebounding after the event, according to Nick Fraser of National Museums Scotland and co-author of the paper.
Fossils of Atopodentatus unicus were first discovered in China’s Luoping Province in Yunnan, and scientifically described in 2014 by Wuhan Institute of Geology and Mineral Resources paleontologist Long Chen and colleagues. When it was revealed to the world, it took both the lay and the scientific communities by storm. It had the standard body of a Middle Triassic marine reptile – a long, sinuous tail, strong body and short legs for swimming – but the most perplexing detail was in its head.
The previous skull, while very well preserved, was crushed and presented something of an enigma. It had a downward-curving jaw, split down the middle and containing a set of incredibly small teeth. This weird portrait soon became popular everywhere as paleoart circles rushed to illustrate the weird beast. Some stretched the split upper jaw to incredible extremes while others closed the split, creating a much more conventional-looking animal.
Based on that distorted skull of a previous specimen, paleontologists got off on the wrong track while figuring out Atopodentatus’ lifestyle. It lived alongside fast-swimming fish-eaters during the Triassic. These included slim dragon-like nothosaurs and dolphin-shaped ichthyosaurs, all early representatives of successful marine reptile groups.
Yet according to the researchers, Atopodentatus might have been a filter-feeder and not a hunter of large struggling prey. It was not even strong enough to bite down hard on bigger animals, as shown by studies of its jaw muscles. Instead, it may have been a filter-feeder though not like most modern whales. Instead Atopodentatus might have sifted food off sandy sea bottoms, searching out tiny invertebrates. Thus it was more like a grey whale than a more active humpback or blue whale, according to Chen. That is, until now.
Original study can be found in Science Advances