Late Jurassic fishes from longing gap, Antarctic Peninsula

Abstract

Few records of Late Jurassic fishes have been reported previously from Antarctica. They include an indeterminate teleost from the Ameghino (Nordenskjöld) Formation at Longing Gap and two incomplete aspidorhyn-chiforms from James Ross Island, all of presumed Late Jurassic age. New fish material recently recovered in the Upper Jurassic of Longing Gap is described. The new material consists of one piece of body squamation, which, based on the structure of the scales, corresponds to a new genus and species (Ameghinichthys antarcticus gen. et sp. nov.) of an indeterminate actinopterygian family; one aspidorhynchiform identified as Vinctifer sp. due to the structure and distribution of the scales; and numerous specimens of a new ichthyodectiform, Antarctithrissops seymouri gen. et sp. nov. This new genus differs from European ichthyodectiforms in the shape of the preopercle, the presence of long sensory preopercular branches almost reaching the posterior margin of the bone, and the uncommon structure of the scales, with a fine layer of bone obscuring the circuli. The presence of Vinctifer in the Antarctic is consistent with its other Gondwanan records. The Ichthyodectiformes, previously known from four European genera, extends the distribution of the group to the southernmost part of the Southern Hemisphere during the Late Jurassic. In contrast to most non-teleostean fishes, the known Late Jurassic teleosts apparently are species endemic to restricted areas in the Southern Hemisphere.