Lazarussuchus (meaning "Lazarus's crocodile") is an extinct genus of amphibious reptile, known from the Cenozoic of Europe. It is the youngest known member of Choristodera, an extinct order of aquatic reptiles that first appeared in the Middle Jurassic. Fossils have been found in Late Paleocene, Late Oligocene, Early Miocene and Late Miocene deposits (~56-11.6 million years ago) in France, Germany, and the Czech Republic. Two species have been named: the type species L. inexpectatus ("unexpected") (Hecht, 1992) from the late Oligocene of France.[1] and L. dvoraki from the early Miocene of the Czech Republic.[2] It was not a large animal; the skull of L. inexpectatus was only about 4.53 centimeters long (1.78 in), with the total preserved body and tail length being just over 30 centimetres.[1] A complete specimen of Lazarussuchus with preserved soft tissue was found from the Late Paleocene of France, but has not been assigned to a species.[3]
The first remains of Lazarussuchus, belonging to the type species L. inexpectatus were described in 1992 from a mostly complete articulated skeleton (Claude Bernard University no Re 437, coll. Gennevaux 92813) found in the Upper Oligocene aged sediments of the Armissan limestone quarry near Narbonne in Aude, France. The genus was named after the "Lazarus Effect", as the remains were the youngest known choristodere fossils, and resembled the most primitive choristodere known, the Middle-Late Jurassic Cteniogenys.[1] In 2005 another species, L. dvoraki, was described from isolated skull bones and vertebrae from the Early-Middle Miocene sediments of the Merkur-North locality in the north-west Czech Republic. The species was named after Zdeněk Dvořák who had collected the specimens.[2] In 2008, remains of Lazarussuchus were reported from the Upper Oligocene sediments of Oberleichtersbach in northern Bavaria, Germany. Remains included 25 bones, and was suggested to probably represent a new species.[4] In 2013, a specimen of Lazurussuchus was described from the late Paleocene aged Menat Formation near Menat, Puy-de-Dôme in France. The specimen, which is an almost complete articulated skeleton (BDL 1819) is largely preserved as an impression, with remnants of disintegrating bone and some preserved soft tissue. The remains were not assigned to a species however, because it could not be robustly diagnosed separately from the two named species.[3] In 2019, in the supplementary information for the paper describing the remains of the extinct ape Danuvius, indeterminate remains of Lazarussuchus were reported from the Hammerschmiede clay pit near Pforzen, Bavaria, Germany. The Hammerschmiede locality has been dated magnetostratigraphically to the base of the Tortonian stage of the Late Miocene, approximately 11.62 million years ago.[5]
Lazarussuchus was small and superficially lizard like in appearance. According to Matsumoto and colleagues (2013) Lazarussuchus is distinguished from all other known choristoderes by the presence of paired nares high on the rostrum, elongated premaxillary bones which replace the maxillae in the anterior part of the rostrum, the slender paired nasal bones are overlapped anteriorly by the premaxillae and wedged between the anterior tips of the prefrontal bones, the nasal bones do not touch the maxillae, the bones on the hind portion of the skull are ornamented with a coarse tuberculous texture, the postorbital and postfrontal bones are fused into a combined postorbitofrontal, the lower temporal fenestrae are closed by the joining of the squamosal, quadratojugal, jugal and postorbitofrontal bones, the cervical ribs are broad and flattened, the trunk ribs are broad and sickle shaped, and are large relative to the size of the vertebrae, the ectepicondylar groove of the humerus is bridged to form a foramen, and the blade of the scapula is slender and parallel sided.[3]