First evidence of brachiopod diversification after the end-Triassic extinction from the pre-Pliensbachian Internal Subbetic platform (South-Iberian Paleomargin)

Abstract

Lower Jurassic brachiopods are widely known in the External Betic Zone. Their occurrence was so far virtually restricted to the easternmost Subbetic Zone where they underwent a diversity burst and radiation event during the late Sinemurian–early Pliensbachian interval, leading to a bloom in brachiopod diversity from the early Pliensbachian onwards. Taxonomical and paleobiogeographical analyses performed in a newly recorded assemblage from the most offshore areas of the Subbetic Basin (Granada province, Spain) reveals that this diversification event occurred earlier than expected hitherto, probably in the Turneri–Obtusum chronozones, as similarly observed in the most intra-Tethyan basins such as the Northern Calcareous Alps and Transdanubian Ranges, illustrating the recovery of the background conditions for the establishment of diversified brachiopod communities after the end-Triassic extinction event. A new rhynchonellide species, Alebusirhynchia vorosi nov. sp., is formally described among the ten different taxa recorded for the first time in this area. The Mediterranean paleobiogeographical affinities revealed by the brachiopod assemblage emphasizes that the onset of the Mediterranean/Euro-Boreal bioprovinciality and the initial brachiopod diversification in the pre-Pliensbachian Internal Subbetic platform took place earlier in the Sinemurian as well, following the Euro-Boreal monotypic record previously reported in this region.