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Microcoelus

Lydekker, 1893 MY-kro-SEE-lus Nomen dubium

From Greek 'mikros' (small) and 'koilos' (hollow); meaning 'small hollow', a reference to the shallow lateral pit on the holotype dorsal vertebra.

85.7–83.6 million years ago Santonian, Late Cretaceous
Late Cretaceous stages

Microcoelus is a dubious genus of small titanosaurian sauropod dinosaur from the Late Cretaceous (Santonian stage) Bajo de la Carpa Formation, Argentina. It is known from only a single dorsal vertebra, although a left humerus was formerly referred to this taxon, but it is now considered to belong to Neuquensaurus. The type (and only known) species is M. patagonicus, described by British paleontologist Richard Lydekker in 1893.

Species

Microcoelus patagonicus Lydekker, 1893 Nomen dubium

Type species

From Patagonia, the region of Argentina where the type material was collected.

Holotype
MLP Ly 23 , Museo de La Plata (unknown)
Material
An anterior dorsal vertebra. Lydekker provisionally associated a left humerus and the posterior half of a caudal vertebra from the same locality; the humerus is now considered to belong to Neuquensaurus.
Horizon
Bajo de la Carpa Formation, Santonian, Late Cretaceous , 85.7–83.6 million years ago
Locality
Right bank of the Río Neuquén, 2 to 4 km upstream from the railroad bridge, Neuquén, Argentina Powell (2003) gives the horizon as "Rio Colorado Formation, Bajo de La Carpa Member?" and the age as "Campanian (Uliana & Dellapa 1981)", a dating of the unit from regional geological maps.

Synonyms of the genus

Name Type Reason
Microsaurops junior objective Replacement name proposed by Kuhn (1963) under the mistaken belief that the original Microcoelus Lydekker, 1893 had been preoccupied. The supposed preoccupier "Microsaurus" (cited from Hatcher 1900; Lull 1910) was itself only a misspelling of Microcoelus, so the replacement was unnecessary. Listed by Olshevsky (1991).

References

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

    Gives the holotype as "MLP Ly 23. An incomplete anterior dorsal vertebra".

    powell2003a
  2. Lydekker, R. (1893). Contributions to a knowledge of the fossil vertebrates of Argentina. I. — The dinosaurs of Patagonia. Anales del Museo de La Plata. Paleontología Argentina 2: 1-16.

    Original description of Microcoelus patagonicus from an anterior dorsal vertebra from Neuquén, alongside Lydekker's other new Patagonian titanosaurs (Argyrosaurus, Titanosaurus australis, T. nanus).

    lydekker1893a
  3. Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2: 1-196.

    Treats Microcoelus as nomen dubium and records Microsaurops Kuhn, 1963 as a junior objective synonym based on the spurious "Microsaurus" misspelling.

    olshevsky1991a
  4. Kuhn, O. (1963). Sauria (Supplementum I). Fossilium Catalogus Animalia 109: 1-87. kuhn1963a
  5. Lull, R. S. (1910). Dinosaurian distribution. American Journal of Science, series 4 29: 1-39. lull1910a
  6. Uliana, M. A.; Dellapé, D. A. (1981). Estratigrafía y evolución paleoambiental de la sucesión Maastrichtiano-Eoterciaria del Engolfamiento Neuquino (Patagonia Septentrional) [Stratigraphy and paleoenvironmental evolution of the Maastrichtian–Eotertiary succession of the Neuquén Embayment (northern Patagonia)]. Actas VIII Congreso Geológico Argentino (San Luis) 3: 673-711.

    Cited by Powell (2003) for the Campanian age of the Rio Colorado Formation.

    uliana1981a