Procheneosaurus

Procheneosaurus (meaning "before the goose lizard [Cheneosaurus]") is a disused genus of hadrosaur dinosaur, based on small skulls with low domes in front of the eyes. It is now believed that the remains referred to its various species were from juvenile individuals of multiple genera of crested hadrosaurs. Peter Dodson's 1975 work first broke them down among Corythosaurus and Lambeosaurus,[1] but later work indicates Hypacrosaurus was included as well.[2] The name Procheneosaurus is thus invalid. Five species have been assigned to it at one time or another: P. praeceps, P. altidens, P. cranibrevis, and P. erectofrons, all from North America; and P. convincens, from Asia.

The genus was coined by William Diller Matthew in 1920 in a photo caption for a skeleton and skull from the late Campanian-age Upper Cretaceous Dinosaur Park Formation of Alberta, Canada.[3] This is normally not considered to be sufficient for publication, and the specimen was later included in Tetragonosaurus. However, Richard Swann Lull requested that the latter name be suppressed in favor of Procheneosaurus, which was granted. The type species, Procheneosaurus praeceps, was described by Parks in 1931 for a skull from the Dinosaur Park Formation, but it was first coined as a species of Tetragonosaurus. He also included in it Matthew's original specimen.[4] This species is now considered to be a specimen of Lambeosaurus lambei, although Procheneosaurus predates Lambeosaurus, and therefore would need to be suppressed to continue to use the well-known name Lambeosaurus. P. altidens, also from the Dinosaur Park Formation, was a new combination erected by Lull and Wright in 1942 for "Trachodon" altidens,[5] and may also be a specimen of Lambeosaurus, although it is based on only a maxilla, so it is difficult to be certain.

P. cranibrevis, from the Dinosaur Park Formation and named as a species of Tetragonosaurus in 1935 by Charles M. Sternberg, was slightly larger than the other species,[6] and was interpreted by Dodson as a juvenile Corythosaurus.[1] Further study has shown that the type specimen is a Lambeosaurus juvenile, based on how the skull bones articulate, and that several other specimens assigned to it are Corythosaurus.[7] P. erectofrons, named by Parks as a species of Tetragonosaurus, is based on a skull from the Dinosaur Park Formation. Dodson found it to be a juvenile Corythosaurus casuarius,[1] although one distinct skeleton from the late Campanian-age Upper Cretaceous Two Medicine Formation of Montana, USA, appears to belong to a young Hypacrosaurus stebingeri.[2]

P. convincens, from the Late Cretaceous of Kazakhstan, is known from a nearly complete skeleton missing only the snout and end of the tail. It was named by A. K. Rozhdestvensky in 1968.[8] It may be synonymous with Jaxartosaurus aralensis,[9] or it could be its own genus,[10] which would require a new generic name.

References

  1. ^ a b c Dodson, Peter (1975). "Taxonomic implications of relative growth in lambeosaurine dinosaurs". Systematic Zoology (Society of Systematic Biologists) 24 (1): 37–54. doi:10.2307/2412696. JSTOR 2412696. 
  2. ^ a b Horner, John R.; and Currie, Phillip J. (1994). "Embryonic and neonatal morphology and ontogeny of a new species of Hypacrosaurus (Ornithischia, Lambeosauridae) from Montana and Alberta". In Carpenter, Kenneth; Hirsch, Karl F.; and Horner, John R. (eds.). Dinosaur Eggs and Babies. Cambridge: Cambridge University Press. pp. 312–336. ISBN 0521567238. 
  3. ^ Matthew, William Diller (1920). "Canadian dinosaurs". Natural History 20 (5): 1–162. 
  4. ^ Parks, William A. (1931). "A new genus and two new species of trachodont dinosaurs from the Belly River Formation of Alberta". University of Toronto Studies, Geological Series 31: 1–11. 
  5. ^ Lull, Richard Swann; and Wright, Nelda E. (1942). Hadrosaurian Dinosaurs of North America. Geological Society of America Special Paper 40. Geological Society of America. pp. 1–242. 
  6. ^ Sternberg, Charles M. (1935). "Hooded hadrosaurs of the Belly River Series of the Upper Cretaceous". Canada Department of Mines Bulletin (Geological Series) 77 (52): 1–37. 
  7. ^ Evans, David C.; Forster, Catherine F.; and Reisz, Robert R. (2005). "The type specimen of Tetragonosaurus erectofrons (Ornithischia: Hadrosauridae) and the identification of juvenile lambeosaurines". In Currie, Phillip J., and Koppelhus, Eva. Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 349–366. ISBN 0-253-34595-2. 
  8. ^ Rozhdestvensky, A.K. (1968). "Hadrosaurs of Kazakhstan". In Tatarinov, L.P. et al. (eds.) (in Russian). Upper Paleozoic and Mesozoic Amphibians and Reptiles. Moscow: Akademia Naul SSSR. pp. 97–141. 
  9. ^ Horner, John R.; Weishampel, David B.; and Forster, Catherine A (2004). "Hadrosauridae". In Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 438–463. ISBN 0-520-24209-2. 
  10. ^ Norman, David B.; Sues, Hans-Dieter (2000). "Ornithopods from Kazakhstan, Mongolia and Siberia". In Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M.; and Kurochkin, Evgenii N.. The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 462–479. ISBN 0-521-55476-X. 

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