A new partial skeleton of Alligatorellus (Crocodyliformes) associated with echinoids from the Late Jurassic (Tithonian) lithographic limestone of Kelheim, S-Germany
Abstract. A slab from the Late Jurassic (Early Tithonian) lithographic limestone exhibiting skeletal material of an atoposaurid crocodyliform associated with four echinoids from the vicinity of Kelheim (S-Germany) is described. The atoposaurid is represented by a row of dorsal paravertebral osteoderms, caudal osteoderms, a caudal vertebra and haemapophyses, dorsal ribs, and parts of the right fore- and hindlimb. Some of the bones have been prepared out of the slab and most of them are preserved three-dimensionally, which is in contrast to the general much flattened preservation of atoposaurid skeletons. This well preserved specimen allows one of the most detailed descriptions of an atoposaurid limb skeleton so far, yielding in particular well preserved manual elements. By comparison with all other known atoposaurid taxa, the specimen can be determined to belong to the genus Alligatorellus based on an identical morphology of osteoderms. In contrast, a high ontogenetic variety and missing data make comparisons of limb ratios in different atoposaurids virtually useless for taxonomy. Femoral and tibial lengths suggest that this specimen is the largest atoposaurid known from the Solnhofen-Eichstätt region. It is suggested that the crocodyliform carcass has been washed into the lagoon and was subsequently embedded together with the tests of four holectypoid echinoids, which probably populated the lagoon.