| Summary: | The few records of Jurassic fishes from Antarctica comprise several actinopterygians. Here we describe the first fish material recovered from the Latady Group, upper Middle to lower Upper Jurassic southern Antarctic Peninsula—one indeterminate actinopterygian and two teleosts, including a Leptolepidae indet. The content of the family Leptolepidae is revised and the assignment of Leptolepidae indet. to family level is based on three uniquely derived characters proposed here (vertebrae with thin and smooth autocentra; autocentra and chordacentra not constricting the notochord; and lack of cavities for adipose tissue in the walls of the autocentra). The new finding changes previous interpretations that Leptolepidae s. str. is a Northern Hemisphere family. The presence of Middle Jurassic leptolepids in Antarctica as well as in the Lower Jurassic of Chile, South America, supports the hypothesis that during Jurassic times more than one center of diversification of teleost fishes were operating in far distant regions of the world. Amongst the new material are the oldest marine teleosts (middle—late Callovian to early Kimmeridgian) recovered from Antarctica. They represent the most southern distribution of teleosts during the Jurassic.
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