a1 CNRS UMR 7207, Département Histoire de la Terre, Muséum National d'Histoire Naturelle, CP 38, 8 rue Buffon, 75005 Paris, France
a2 Universidad del País Vasco/EHU, Facultad de Ciencia y Tecnología, Departamento de Estratigrafía y Paleontología, Apartado 644, 48080 Bilbao
a3 Office Chérifien des Phosphates, Centre Minier de Khouribga, Khouribga, Morocco
a4 Office Chérifien des Phosphates, Centre Minier de Ben Guerir, Ben Guerir, Morocco
The discovery of new specimens of Pachyvaranus crassispondylus Arambourg, 1952 from the Maastrichtian phosphates of Morocco and Syria enables us to (1) redescribe in detail this poorly known varanoid lizard, (2) provide a more detailed diagnosis and (3) re-evaluate the systematic affinities of this taxon within squamates. The latter is placed in Pachyvaranidae nov., considered a new unranked clade of non-pythonomorph Varanoidea. The intense pachyosteosclerosis observed in the vertebrae and ribs suggests a primarily aquatic mode of life for Pachyvaranus. This is in accordance with the sedimentological context (shallow marine environment). As for its palaeobiogeographical distribution, Pachyvaranus is a component of the marine reptile assemblages from the southern margin of the Mediterranean Tethys, around palaeolatitudes 20° N. The osteoderms previously referred to this taxon by Arambourg are reanalysed and assigned to a teleost fish.
(Received November 02 2009)
(Accepted May 27 2010)
(Online publication July 09 2010)