LARGE AND MAINLY UNNOTICED: THE FIRST LOWER TITHONIAN RECORD OF A SUSPENSION-FEEDING PACHYCORMID IN THE SOUTHERN GONDWANA

GOUIRIC CAVALLI, S.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2016

0002-7014

A large fossil specimen could be easily unnoticed specially when the specimen osteology is not well known, is usually represented by fragmentary material, and have a sparsely ossified skeleton giving a low preservation potential. This is particularly true for the suspension-feeding Pachycormiformes, a clade of actinopterygians. This work provides the description of a complete gill raker recovered from the Upper Jurassic (lower Tithonian) levels of the Vaca Muerta Formation at Cerro Lotena, Neuquén Province, southwestern Argentina. The specimen is referred to the suspension-feeding pachycormid, Leedsichthys, based on similarities in size and shape morphology of the gill raker stalk, the shape of the gill raker base and for having similar morphology of the fimbriae (growing tongue-like distally). Despite suspension-feeding pachycormids are mainly known from Laurasia, some remains were also recovered in Gondwana. The lower Tithonian Leedsichthys record extends the geographic and stratigraphic range of the suspension-feeding clade and that of the genus Leedsichthys.