CEB Committe on Evolutionary Biology

New species of tetrapods found that bridge Romer’s Gap

A micro-CT scan of the Aytonerpeton microps specimen discovered by Ben Otoo. 

Early tetrapods — the first four-legged vertebrates — diversified rapidly after the mass extinction at the end of the Devonian period 358 million years ago into the ancestors of amphibians on one hand and the ancestors of amniotes (reptiles, birds, and mammals) on the other.  However, Romer’s Gap, an apparent hiatus in the fossil record during the early Carboniferous period, has obscured their evolution in the aftermath of the extinction.  A new paper published in Nature Ecology and Evolution describes five new species of Scottish tetrapods from the time of this gap, one of which was discovered by CEB student Ben Otoo in the course of his master’s research at Cambridge. The phylogenetic placement of the new tetrapod species strengthen support for a deep divergence between the amphibian and amniote lineages, and shows that the early Carboniferous was not a time of low tetrapod diversity.  This study is part of the TW:eed Project, an international collaboration investigating the animals, ecosystems, and environments within Romer’s Gap.  The TW:eed project is part of the long-term ongoing collaboration between Cambridge, Chicago, and Edinburgh on tetrapod evolution.