Revision of the status of Saurolophus (Hadrosauridae) from California, USA
The occurrence of Saurolophus from the Moreno Formation (late Maastrichtian) of California is investigated and an incomplete, poorly preserved, skull (LACM/CIT 2852) is described. The skull lacks the braincase (including the frontals) and much of the nasals, and the preserved portions are crushed or plastically deformed, which makes anatomical interpretations difficult. A preserved midline fragment of the conjoined nasals suggests that it lacked a gryposaur-like “Roman nose”, but the nature of the crest, if present, is impossible to determine with certainty. A phylogenetic analysis places this specimen as either the sister taxon of Saurolophus or as the sister taxon to a clade comprising Edmontosaurus and Anatotitan. There is no compelling morphological evidence to support the previous assignment of LACM/CIT 2852 to Saurolophus rather than to Edmontosaurus, and its poor preservation prevents positive assignment to any taxon below Hadrosaurinae indet. Given its geographic setting and morphological uncertai...