New preliminary data on crocodylomorphs and anurans from the early Eocene Lignitifero Formation (SW Sardinia, Italy)

The Eocene vertebrate record of Sardinia reveals a diverse continental fauna, including mammals, reptiles, and freshwater fishes. However, microvertebrate assemblages from this interval remain poorly documented. Here we report new preliminary data on Eocene microvertebrate remains from the Lignitifero Formation (Ypresian–early Lutetian) exposed at Tanca Aru (Vallermosa, SW Sardinia, Italy). The fossil-bearing succession consists of continental deposits interpreted as alluvial plain sediments. The material was recovered from a thin (~8 cm) bioclastic lacustrine limestone layer and processed using a 10% acetic acid solution. The assemblage includes two teeth assigned to Crocodylomorpha indet. and three maxillary fragments referred to Anura indet. The crocodylomorph teeth are characterized by apicobasal ridges, well-developed carinae, and a marked basal constriction; one specimen shows a spatulate morphology, whereas the other, although incomplete, appears to be caniniform (Frey & Monninger, 2010). The anuran remains consist of maxillary fragments bearing a linear series of well-defined tooth alveoli, interpreted as housing pedicellate teeth, and nutrient foramina along the labial surface. The bone is thin and slightly curved, consistent with an anuran maxilla. These remains represent the first documented occurrence of crocodylomorph and anuran material from the Lignitifero Formation. This assemblage expands current knowledge of Sardinia’s Eocene vertebrate diversity and provides new insights into the paleoecology and paleobiogeographic relationships of southwestern Europe during the Paleogene.