|A 3D model showing the positions of the skeletons of |
Broomistega and Thrinaxodon within the 250 million
year old fossil burrow
Now an example of this behavior has been found in the fossil record, hundreds of millions of years ago. The Permian Great Dying was the greatest mass extinction in the history of the planet, decimating around 80% of all life on Earth 250 million years ago.
Volcanic eruptions on a global scale, wildfires, earthquakes and climate change made the planet a harsh place to live on. Yet this fossil discovery from the Karoo Basin in South Africa has shown how animals may have dealt with the inhospitable conditions facing them. An international team of palaeontologists analysed a 250 million year old fossil burrow at the European Synchrotron Radiation Facility (ESRF). Their results showed something amazing: at the end of the burrow lay the skeleton of a mammal ancestor, a therapsid reptile known as Thrinaxodon.
However, it was not alone. Next to it was the remains of an amphibian, Broomistega. The sediments from that Karoo basin show that they were derived from a flash flood, the event which led to the preservation of the burrow and its inhabitants. Scans of the amphibian revealed that some of its ribs were broken, which most likely led to it seeking shelter.
|An artist's impression of Broomistega creeping into the |
burrow of an aestivating Thrinaxodon
'Burrow-sharing by different species exists in the modern world, but it corresponds to a specific pattern,' said Dr Vincent Fernandez from Wits University, South Africa. 'For example, a small visitor is not going to disturb the host. A large visitor can be accepted by the host if it provides some help, like predator vigilance. But neither of these patterns corresponds to what we have discovered in this fossilized burrow. Thanks to the unique possibilities for high quality imaging of fossils developed during the last decade at the ESRF, these unique specimens remain untouched, protected by their mineral matrix,' added Dr Paul Tafforeau from the ESRF.
What is equally important is understanding how prehistoric creatures interacted with each other and how these interactions built food webs, ecosystems and how these links ultimately drove evolution forward. This fossil discovery offers a unique glimpse of not just what creatures were like, but how they lived.