Open Paleo

Dysganus

Cope, 1876 dis-GANN-us Nomen dubium

From Greek dys- (bad/rough) + ganos (tooth enamel): 'rough enamel', referring to the texture of the fossil teeth.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Dysganus (meaning "rough enamel") is a dubious genus of ceratopsian dinosaur from the Campanian stage of the Late Cretaceous. The fossil teeth referred to Dysganus were first collected by Charles Sternberg from the Judith River Formation of Montana and later described by Edward Drinker Cope. All of the species are now seen as dubious ceratopsians, though referred material from tyrannosaurids and hadrosaurids were found in New Mexico.

Species

Dysganus encaustus Cope, 1876 Nomen dubium

Type species

From Greek 'encaustus' meaning 'burnt in', referring to the concave tip of the type tooth.

Lectotype
AMNH 5739 , American Museum of Natural History
Material
Single fragmentary ceratopsian maxillary tooth (base of the crown just above the root) preserving part of one marginal ridge, the raised cingulum base, and part of the tall median ridge; worn occlusal surface present.
Notes
Cope (1876) based the species on a chimeric suite of six teeth kept under AMNH 5739 (one ceratopsian maxillary tooth, a second ceratopsian fragment, three hadrosaur teeth, and a doubtful fragment); W. D. Matthew later designated the ceratopsian maxillary tooth as the type, treated as the lectotype.
Horizon
Judith River Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Dog Creek, Montana, United States

References

  1. Cope, E. D. (1876). Descriptions of some vertebrate remains from the Fort Union Beds of Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 28: 248-261. cope1876a
  2. Coombs, W. P. Jr.; Galton, P. M. (1988). Dysganus, an indeterminate ceratopsian dinosaur. Journal of Paleontology 818-821.

    Redescription of Cope's chimeric type material; documents Matthew's designation of one ceratopsian tooth (AMNH 5739) as the type and regards Dysganus and all four of its species as nomina dubia.

    coombs1988a
  3. Brett-Surman, M. K. (1989). A revision of the Hadrosauridae (Reptilia: Ornithischia) and their evolution during the Campanian and Maastrichtian. 1-272. Doctoral thesis, The George Washington University.

    Finds none of the Dysganus teeth diagnostic below family level and all four species nomina dubia.

    brett-surman1989a
  4. Mallon, J. C.; Ott, C. J.; Larson, P. L.; Iuliano, E. M.; Evans, D. C. (2016). Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA. PLOS ONE 11(5): e0154218. Public Library of Science (PLoS). doi:10.1371/journal.pone.0154218

    Lists the four Dysganus species among the taxonomically invalid ceratopsids of the Judith River Formation.

    mallon2016a