A fragmentary leptonectid ichthyosaurian from the lower Pliensbachian of Luxembourg

Abstract

Despite abundant fossils, the quality of the fossil record of Early Jurassic marine reptiles strongly fluctuates with time and space. Pliensbachian strata have yielded very few marine reptile remains, especially outside of England, obscuring the evolution of marine reptiles during the middle part of the Early Jurassic. We report a new Pliensbachian locality from Luxembourg that contains abundant marine fauna and ichthyosaurian remains likely representing a single individual, composed of a partial snout, a possible surangular, two centra, and several ribs and gastralia. Ammonites and belemnites place this locality within the Valdani-Luridum Ammonite subzones of the Ibex Ammonite Zone, lower Pliensbachian. We assign the new ichthyosaur specimen to the clade Leptonectidae, using a combination of features from the snout and teeth. This specimen indicates that large neoichthyosaurians were present in multiple places of the European archipelago in all stages of the Early Jurassic and suggests that the ichthyosaurian faunae of western Europe remained essentially similar across the Sinemu-rian–Pliensbachian interval.