Tetraodontiformes (Osteichthyes, Actinopterygii) from the Miocene of Argentina: the first and southernmost record of fossil Tetraodontidae

GOUIRIC CAVALLI, SOLEDAD; AZPELICUETA, MARÍA DE LAS MERCEDES; ALBERTO LUIS CIONE

COMPTES RENDUS PALEVOL

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2020 vol. 20 p. 585 - 596

1631-0683

Teleostean evolution involves a huge variation in tooth morphology. This variation is related to the exploration and exploitation of very diverse dietary niches.Among extant fishes, several families of the order Tetraodontiformes (e.g., pufferfishes, porcupinefishes, ocean sunfishes) have evolved highly specialized beak-like tooth structures. Here we provide the first description of tetraodontiform crushing beaks from Argentina. A single complete premaxillary beak recovered from the lower?early middle Miocene Gaiman Formation in Chubut Province is assigned to Molidae based on its premaxillaries being completely fused to one another along the midline, general morphology, and size. Moreover, due to the putative 26 presence of rows of teeth fused to the thick and massive bone structure, the specimen might belong to the genus Ranzania. Several premaxillary beaks recovered in the middle?late Miocene Paraná Formation of Entre Ríos Province are assigned to Tetraodontidae based on the presence of long, slender, rod-like, and parallel dental units; premaxillae not fused in the midline but articulated by interlocking emarginations, and a few small and one large trituration dental units. Argentinian tetraodontiform fishes inhabited the warm-temperate ?Paranense? and ?Patagonian? seas during the middle?late Miocene (marine transgressions developed in southeastern South America); these specimens are the southernmost fossil record of the group worldwide. Tetraodontiforms are extremely rare in recent Argentinian marine waters. The new fossil records agree with the higher sea water surface temperatures suggested both locally and worldwide for the Miocene.