Posted on 05/05/2013 12:44:32 PM PDT by SunkenCiv
Prof Christian Sidor and his colleagues headed by Dr Linda Tsuji, also from the University of Washington, created two ‘snapshots’ of four legged-animals about 5 million years before and again about 10 million years after the Earth’s largest mass extinction (about 252 million years ago).
Prior to the extinction event, for example, the pig-sized Dicynodon was a dominant plant-eating species across southern Pangea.
Pangea is the name given to the landmass when all the world’s continents were joined together. Southern Pangea was made up of what is today Africa, South America, Antarctica, Australia and India. After the mass extinction at the end of the Permian, Dicynodon disappeared and other related species were so greatly decreased that newly emerging herbivores could suddenly compete with them...
The snapshot 10 million years after the extinction event reveals that archosaurs were in Tanzanian and Zambian basins, but not distributed across all of southern Pangea as had been the pattern for four-legged animals prior to the extinction.
Archosaurs are the group of reptiles that includes crocodiles, dinosaurs, birds and a variety of extinct forms. They are of interest because it is thought they led to animals like Asilisaurus, a dinosaur-like animal, and Nyasasaurus parringtoni, a dog-sized creature with a five-foot tail that scientists in December 2012 announced could be the earliest dinosaur, or else the closest relative found so far...
It revealed that before the extinction event 35 percent of four-legged species were found in two or more of the five areas studied, with some species having ranges that stretched 1,600 miles (2,600 kilometers), encompassing the Tanzanian and South African basins. Ten million years after the extinction event, there was clear geographic clustering and just 7 percent of species were found in two or more regions.
(Excerpt) Read more at sci-news.com ...
10 million years after the mass extinction, members of the archosaur reptiles – such as the 10-foot-long Asilisaurus pictured – had more restricted geographic ranges compared to the communities of four-legged animals that existed before the extinction (Marlene Donnelly / Field Museum of Natural History)
The pig-size Dicynodon was part of a large, dominant group of plant eaters found across the southern hemisphere until the mass extinction event weakened their numbers so that newly emerging herbivores could compete (Marlene Donnelly / Field Museum of Natural History)
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From looking at that one I’d have thought it to be a dorkasaurus.
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