Open Paleo

Clasmodosaurus

Ameghino, 1899 KLAZ-mo-do-SAWR-us Nomen dubium

From Greek 'klasma' (fragment) and 'odon' (tooth) plus 'sauros' (lizard); meaning 'fragment-tooth lizard', alluding to the fragmentary tooth material on which the genus was based.

Clasmodosaurus is a sauropod from the Late Cretaceous of southern Patagonia, Argentina, founded on a few isolated teeth. Ameghino allied it with Ornithopsis; Huene (1929) reported the teeth as sauropod and as coelurosaurian in different parts of the same work, and finally judged them most likely coelurosaurian. Powell (2003) treated them as titanosaurid, while holding that dental morphology alone cannot diagnose a dinosaur genus.

Species

Clasmodosaurus spatula Ameghino, 1899 Nomen dubium

Type species

From Latin 'spatula' (small flat blade), likely referring to the shape of the type teeth.

Syntype
Not catalogued , Museo de La Plata (unknown)
Material
Three teeth (one cylindrical crown fragment with root base, one apical crown fragment, and one small nearly complete posterior crown); Huene (1929) figured them as plate 40, figs. 3-5.
Horizon
Late Cretaceous
Locality
Río Sehuen, Santa Cruz, Argentina The erecting paper places the type teeth no more finely than the Cretaceous of Patagonia, in the Guaranitic formation, an obsolete name covering much of the Patagonian Upper Cretaceous. Huene (1929) fixes the locality from Carlos Ameghino's account, on the eastern slope of a southern tributary of the Río Sehuen, about 50 km east of Lago Viedma and 30 km south of the settlement of Mata Amarilla, in the area Ameghino called Par Aik; Powell (2003), citing Huene, prints "Western slope". Powell refers that locality only tentatively to the Cardiel Formation and gives its age as Late Cretaceous, reporting both Coniacian and Maastrichtian estimates for the unit. Successive workers have circumscribed the Upper Cretaceous units of this part of the Austral Basin differently — the Cerro Fortaleza Formation has also been treated as the Pari Aike, Chorrillo and Mata Amarilla formations — and none of the works cited here assigns these teeth to a formation without qualification.

Synonyms

  • Clasmodon spatula informal

    The label placed by Ameghino on the original specimens read "Clasmodon spatula"; Huene (1929) noted this as a labeling variant rather than a formally published name.

References

  1. Ameghino, F. (1899). Sinopsis geológico-paleontológica. Suplemento (adiciones y correcciones) [Geological-paleontological synopsis. Supplement (additions and corrections)]. 1-13.

    In Spanish. Erects Clasmodosaurus spatula (p. 9) with a short diagnosis of the teeth, allying it with Ornithopsis Seeley; available under ICZN Article 12, though widely regarded as a nomen dubium.

    ameghino1899b
  2. Huene, F. V. (1929). Los saurisquios y ornitisquios del Cretáceo Argentino [The Saurischians and Ornithischians of the Argentine Cretaceous]. Anales del Museo de La Plata, series 2 3: 1-196.

    Full redescription of the three type teeth — crown outline, labial and lingual enamel folds, crown edges and pulp lumen — with the first illustration (plate 40, figs. 3-5), and the type locality.

    huene1929a
  3. Powell, J. E. (1986). Revisión de los titanosáuridos de América del Sur. Doctoral thesis, Universidad Nacional de Tucumán, Tucumán, Argentina.

    Unpublished doctoral thesis, 493 pp., as cited in Powell's own 2003 revision of it. The two are separate works: this thesis is in Spanish, while the revision published on it, Powell (2003), is in English. The thesis is retained here because the literature cites it as the first mention of several names, which as a thesis it did not make available.

    powell1986a
  4. Powell, J. E. (2003). Revision of South American Titanosaurid dinosaurs: palaeobiological, palaeobiogeographical and phylogenetic aspects. Records of the Queen Victoria Museum 111: 1-173.

    Places the type teeth at the Río Sehuen locality, refers it tentatively to the Cardiel Formation, and lists the genus as a titanosaurid nomen dubium.

    powell2003a
  5. Lacovara, K. J.; Lamanna, M. C.; Ibiricu, L. M.; Poole, J. C.; Schroeter, E. R.; Ullmann, P. V.; Voegele, K. K.; Boles, Z. M.; Carter, A. M.; Fowler, E. K.; Egerton, V. M.; Moyer, A. E.; Coughenour, C. L.; Schein, J. P.; Harris, J. D.; Martínez, R. D.; Novas, F. E. (2014). A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina. Scientific Reports 4(1). Springer Science and Business Media LLC. doi:10.1038/srep06196

    Records that the beds of the Cerro Fortaleza Formation have also been referred to the Pari Aike, Chorrillo and Mata Amarilla formations.

    lacovara2014a