"Romer's Gap" Is Filled

Taking a quick break from all of the current Triassic papers because this is pretty significant for the field of vertebrate paleontology.

Smithson, T. R.,Wood, S. P., Marshall, J. E. A., and J. A. Clack. 2012. Earliest Carboniferous tetrapod and arthropod faunas from Scotland populate Romer's Gap. PNAS [advance online] doi: 10.1073/pnas.1117332109

Abstract - Devonian tetrapods (limbed vertebrates), known from an increasingly large number of localities, have been shown to be mainly aquatic with many primitive features. In contrast, the post-Devonian record is marked by an Early Mississippian temporal gap ranging from the earliest Carboniferous (Tournaisian and early Viséan) to the mid-Viséan. By the mid-Viséan, tetrapods had become effectively terrestrial as attested by the presence of stem amniotes, developed an essentially modern aspect, and given rise to the crown group. Up to now, only two localities have yielded tetrapod specimens from the Tournaisian stage: one in Scotland with a single articulated skeleton
and one in Nova Scotia with isolated bones, many of uncertain identity. We announce a series of discoveries of Tournaisian-age localities in Scotland that have yielded a wealth of new tetrapod and arthropod fossils. These include both terrestrial and aquatic forms and new taxa. We conclude that the gap in the fossil record has been an artifact of collection failure.