Clasmodosaurus Temporal range: Late Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Macronaria
Clade:	†Titanosauria
Genus:	†Clasmodosaurus Ameghino, 1898
Species:	†C. spatula
Binomial name
†Clasmodosaurus spatula Ameghino, 1898

Clasmodosaurus (meaning "fragmentary tooth reptile") is a genus of titanosaurian sauropod dinosaur from the Mata Amarilla Formation and the Cerro Fortaleza Formation.^[1] It lived during the Late Cretaceous in what is now Argentina. It is known from five fossilized and assorted teeth, but is diagnosed by a unique combination of characters.^[1][2]

History

Clasmodosaurus was named by Florentino Ameghino in 1898, but remained largely unknown for decades after its discovery.^[3] It was originally considered a sauropod, but Friedrich von Huene suggested that it could be a coelurosaur or synonymous with Loncosaurus, which he considered to be a carnosaur.^[2] Like Loncosaurus, its taxonomy remained unclear with it regarded as a theropod on the rare occasions it was mentioned.^[2] However, Jaime Powell suggested that it was a dubious genus of sauropod in 1986, an identification which has been accepted since. Like diplodocoids and titanosaurs, it had narrow tooth crowns, and it is typically regarded as a titanosaur like most Late Cretaceous sauropods.^[2] More recently, a revision of Ameghino's collection and new discoveries in the Cerro Fortaleza Formation find the taxon to also hail from this formation.^[1]

Description

The teeth of Clasmodosaurus spatula were polygonal in cross section rather than round, an unusual trait also found in the titanosaur Bonitasaura salgadoi.^[4] However, these teeth are much larger and more robust than those of Bonitasaura, with well-defined longitudinal ridges and grooves, resembling diamantinasaur teeth in some aspects.^[1]