Middle–Upper Triassic marine vertebrates of Mallorca (Balearic Islands, western Mediterranean)

Abstract

ABSTRACT During the Triassic, many groups of predatory marine reptiles appeared and diversified. On Mallorca, fossils of marine reptiles have been found in Muschelkalk (Anisian–Ladinian) and Keuper (Carnian–Norian) facies. Here we describe an anterior caudal vertebra of a basal ichthyosauriform similar to Grippidia (Reptilia: Ichthyosauriformes) from the Ladinian carbonate ramps of the Muschelkalk of Mallorca, which fills a biogeographic gap for the group, hitherto only known from the eastern and western margins of Panthalassa. The most plausible hypothesis to explain the fact that the Mallorcan specimen is younger than all the other related species described so far is supported by a rather isolated condition of the carbonate ramps surrounding eastern Iberia during the Anisian, which might point to a relict character of the Mallorcan species, representing the youngest record of basal ichthyosauriforms to date. Moreover, an epiphysis of an indeterminate reptile and four vertebrae assigned to Nothosaurus sp. (Reptilia: Eosauropterygia) from the Keuper sabkhat provide a new record of the latter genus on Mallorca, which falls within its known distribution area. Therefore, the present work provides an exhaustive review of all the marine vertebrate fossils found so far in the Middle–Upper Triassic of Mallorca, some of them with remarkable palaeobiogeographical implications.