Wednesday, 7 December 2011

The Varanopids Survived Far Longer Than Previously Thought

The remains of varanopids Varanodon (top) and Aerosaurus (bottom)
Giant, predatory reptiles first evolved in the Permian period. Perhaps the most famous example is Dimetrodon, the vicious sail-backed predator which starred in the final episode of the acclaimed BBC series 'Walking with Monsters.' However this creature was by no means the earliest. The varanopids, specifically Archaeovenator, own the title as the first giants. The varanopids were a diverse class but it was thought that they perished during a small extinction which marked the end of the middle Permian.

Recent analysis of a partial skull and jaw from the youngest known, primitive, mammal-like ancestor suggests that they may have lasted rather longer than previously thought. The 260 million year old fossils showed that the varanopids' diet consisted of over 70% meat, making them top predators within their ecosystem. Sean Modesto, the leader of the study and professor at the Cape Breton University, believes that these features contributed to their survival, making their existence far longer than was previously thought.

According to Modesto 'these ancient animals really looked like modern goannas or monitor lizards.' These predators were agile and 'sleek-looking' against their mammalian contemporaries. Robert Reisz, from the University of Toronto Mississauga, added that the varanopids 'seem to have survived a major change in the terrestrial fauna that occurred during the Middle Permian, a poorly understood extinction event in the history of life on land.' Discoveries like these will make us think again and re-investigate what we do know.