A re-description of the teleosauroid Macrospondylus bollensis (Jaeger, 1828) from the Posidonienschiefer Formation of Germany

Abstract Teleosauroid crocodylomorphs were a successful, diverse and abundant clade that expanded near-globally during the Jurassic Period. Teleosauroids are commonly found in Toarcian strata (Early Jurassic) within Europe, with multiple unique specimens pertaining to four taxa having been discovered in the Posidonienschiefer Formation (= Posidonia Shale) in southwestern Germany. The majority of these specimens have been referred to Macrospondylus bollensis (Jaeger, 1828), a basal machimosaurid species previously assigned to the genus Steneosaurus . Macrospondylus bollensis , as a species, is known to have a long and impressive history; unfortunately, the holotype of Ma. bollensis is poorly understood, rarely referenced in the current literature and is often incorrectly thought to be a teleosauroid specimen from Whitby. The actual holotype (housed at the Museum für Mineralogie und Geologie in Dresden), while badly burned, offers valuable information on basal teleosauroid postcranial material. We provide a detailed re-description of Macrospondylus bollensis , recognize it as a valid taxon and compare it with other Toarcian and machimosaurid teleosauroids. In addition, we evaluate the ecology and biogeographical distribution of Macrospondylus .