Smithsonian: Paleontologists Uncover Fossil Impressions of Giant, Alligator-Like Amphibians #fossil #paleontology #amphibian #southafrica #permian

An artist’s reconstruction of Rhinesuchus, a rhinesuchid temnospondyl Dmitry Bogdanov via Wikimedia Commons under CC By-SA 3.0

Smithsonian Magazine has a story about the discovery of alligator-like amphibians from the Permian Period.  The animals, Rhinesuchus, were found in the Karoo Basin in South Africa.  They lived more than 255 million years ago.  They are thought to be salamander-like, but the size of modern day alligators.  The rhinesuchid temnospondyls were described in the paper "Unique trackway on Permian Karoo shoreline provides evidence of temnospondyl locomotory behaviour", which was published in the journal PLOS One.

Determining what sort of organism made a trace fossil, including those on the Dave Green paleosurface, can be a challenging task. Body fossils, such as bones, are rarely found with footprints and body impressions. Museums of Western Colorado paleontologist Julia McHugh, who wasn’t involved with the new study, notes that sometimes paleontologists find tracks or other trace fossils before they find bones. Experts have to work backward from those footprints and other traces through the list of creatures that could have possibly left such imprints. In this case, based on the size of the trace fossils, their shape and the wealth of previous research on animals that lived in the area at the end of the Permian, a rhinesuchid temnospondyl is the best fit, McHugh says.

Most of what paleontologists have come to understand about temnospondyls has come from their bones, including broad, flat-topped skulls that gave their noggins a passing resemblance to a toothy toilet seat. But the trace fossils—scrapes and scours in the rock—reveal the shape and behavior of animals that lived millions of years before the dinosaurs. “I feel like each time I go, I find something new or something that I hadn’t seen before,” Groenewald says. Tracks left by the temnospondyls as they slowly moved around the rivers dot the stone, as well as whole-body impressions created when the amphibious creatures rested on the silty bottom.