An international team of researchers studied the parareptiles, a diverse group of bizarre-looking terrestrial vertebrates which varied in shape and size. Some were small, slender, agile and lizard-like creatures, while others attained the size of rhinos; many had knobbly ornaments, fringes, and bony spikes on their skulls.
The researchers found that, surprisingly, parareptiles were not hit much harder by the end-Permian extinction than at any other point in their 90 million-year history.
Furthermore, the group as a whole declined and diversified time and time again throughout its history, and it was not until about 50 million years after the end-Permian crisis that the parareptiles finally disappeared.
During the end-Permian extinction, some 250 million years ago, entire groups of animals and plants either vanished altogether or decreased significantly in numbers, and the recovery of the survivors was at times slow and prolonged before new radiations took place.
By studying the fossil record, palaeontologists can examine how individual groups of organisms responded to the end-Permian event and assess just how dramatic it was. However, as the quality and completeness of the fossil record varies considerably, both geographically and stratigraphically, palaeontologists need to find a way to 'join the dots' and piece together the fragments of a complex mosaic to give a more satisfactory and better picture of ancient life's diversity.
The team led by Dr Marcello Ruta of Bristol's School of Earth Sciences, and including scientists from Germany, Brazil and North America, used the evolutionary relationships among known parareptiles to produce a corrected estimate of changing diversity through time.
Dr Marcello Ruta said: "Evolutionary relationships can be superimposed on a time scale, allowing you to infer missing portions of past diversity. They are powerful tools that complement and refine the known reco
|Contact: Hannah Johnson|
University of Bristol