The tracks may have been made by giant temnospondyls such as Uranocentrodon senecalensis.
Nationalgeographic.co.id – Two-metre-long ancient amphibians swam like crocodiles long before true crocodiles existed, according to a study published March 29, 2023 in the open access journal PLOS ONE by David P. Groenewald of the University of the Witwatersrand, South Africa and colleagues.
The paper is titled “Unique trackway on Permian Karoo shoreline provides evidence of tempnospondyl locomotory behavior.”
Dr David Groenewald, lead author of the study, said. “The tracks are unique, and as far as I know, the only Permian body impression of a rhinesuchid amphibian this size.”
During the Late Permian Period more than 250 million years ago, South Africa was home to the temnospondyl rhinesuchid, a large predatory amphibian with a body similar to that of a large crocodile or salamander.
The Karoo supergroup rocks are found throughout most of southern Africa, reaching as far east as Madagascar and as far north as the Democratic Republic of the Congo and south as Kenya. Traces of it have been found in the main basin, which includes most of South Africa and Lesotho.
Although the rocks date back more than 150 million years from the Carboniferous to the Jurassic, they are extremely useful for studying the time known as the Permian. This period is important to study because many major animal groups, such as sharks and turtles, first became prominent at this time.
Trace fossils (left) are similar to those of modern alligators (right), indicating they swam in a similar way.
During the Permian, the Karoo was thought of as a large, shallow sea surrounded by rivers and lagoons, with soft sediments that helped preserve the fossilized bodies of various types of animals. But sediments are also suitable for preserving fossil tracks, which capture aspects of animal behavior.
The fossils in this study were found on the surface of Dave Green’s palaeo, named after a landowner that caught the attention of researchers in the 1990s. It is a series of tracks left by the feet, fins, abdomen and tail of ancient animals.
For example, the small fossils that form the grooves are believed to have been left behind by the fins of ancient fish as they dragged along the sand while swimming. Meanwhile, tiny footprints are believed to have been left by dicynodonts, whose footprints have been found elsewhere in the Karoo basin.
However, it is the larger impression that has caught the attention of scientists. Forming two nearly circular routes, it is believed to represent paths taken by one or two temnospondyls more than 250 million years ago.
“Unlike other fossil tracks, it’s not the footprints that stand out, but the tail and body tracks,” explains David. “It is larger than many other fossil amphibian body tracks, which are often less than 30 centimeters.”
