Prenocephale

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Prenocephale
Temporal range: Late Cretaceous, 83–66Ma
Prenocephale prenes.JPG
Cast of a P. prenes skull
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Pachycephalosauridae
Genus: Prenocephale
Maryańska & Osmólska, 1974
Species
  • P. prenes Maryńska & Osmólska, 1974 (type)
  • P. brevis (Lambe, 1918 [originally Stegoceras])
  • P. edmontonensis? (Brown & Schlaikjer, 1943 [originally Sphaerotholus])
  • P. goodwini? (Williamson & Carr, 2002 [originally Sphaerotholus])
Synonyms

Prenocephale was a small pachycephalosaurid dinosaur genus from the Late Cretaceous (from the Campanian through to the Maastrichtian) and was similar in many ways to its close relative, Homalocephale, which may simply represent Prenocephale juveniles. Adult Prenocephale probably weighed around 130 kilograms (290 lb) and measured around 2.4 metres (8 ft) long. Unlike the flattened wedge-shaped skull of Homalocephale (a possible juvenile trait also potentially seen in early growth stages of Pachycephalosaurus), the head of Prenocephale was rounded and sloping. The dome had a row of small bony spikes and bumps. It lived in what is now Mongolia, but in high upland forests, not the dry deserts of Mongolia today. Fossils have also been found in the Kirtland Formation of New Mexico and Colorado. [1]

Description[edit]

An artist's impression of Prenocephale

Like some other pachycephalosaurs, Prenocephale is known only from skulls and a few other small bones.[2] For this reason, reconstructions usually depict Prenocephale as sharing the basic body plan common to all of the other Pachycephalosauria: a stout body with a short, thick neck, short forelimbs and tall hind legs.

The head of Prenocephale was comparable to that of Stegoceras, albeit with closed supratemporal fenestrae. Also, the paired grooves above the supraorbitals/prefrontals (along with a posterior parietal that restricts the frontal dome) are absent in Prenocephale. This differentiates the species from Stegoceras, as such features are common in the latter. It has been suggested that Prenocephale's supposed relatives, Sphaerotholus and Homalocephale, are all synoynms of Prenocephale. If this is the case, Prenocephale would have also lived in North America as well as in Mongolia.[3][4]

Diet[edit]

As with most of its relatives, scientists do not yet know what these dinosaurs ate. However the premaxillary teeth and muzzle are not as wideset as in its relative Stegoceras, indicating different feeding preferences, possibly that Prenocephale was a more selective forager.[5] Some scientists[who?] suggest that it may have been an omnivore, eating both plants and insects. However, most experts agree that Prenocephale (and the other pachycephalosaurs) browsed on leaves and fruit.

Classification[edit]

Front view of skull

Prenocephale is a member of the Pachycephalosauria, a large clade of herbivorous/omnivorous dinosaurs from the Late Cretaceous. Initially, the species P. brevis, P. edmontonensis, and P. goodwini were identified as Stegoceras, but are now referrable to Prenocephale.[5]

It has also been proposed by Robert Sullivan that P. brevis, P. edmontonensis, and P. goodwini come together to form a clade with the Asian taxa P. prenes as a currently unresolved sister group. Tylocephale has been interpreted as the sister taxon to the Prenocephale clade. The species Sphaerotholus buchholtzae could be a subjective junior synonym of P. edmontonensis.[6][7] They all possess a distinct row of nodes on the squamosal and parietal areas of the skull roof.

Below is a cladogram modified from Evans et al., 2013.[8]

 Pachycephalosauria 

Wannanosaurus yansiensis


 Pachycephalosauridae 


Colepiocephale lambei



Hanssuesia sternbergi



Stegoceras novomexicanum



Stegoceras validum





Goyocephale lattimorei




Homalocephale calathocercos




Tylocephale gilmorei




"Prenocephale" brevis




Amtocephale gobiensis





Acrotholus audeti



Prenocephale prenes






Alaskacephale gangloffi



Pachycephalosaurus wyomingensis





Sphaerotholus buchholtzae



Sphaerotholus goodwini












References[edit]

  1. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 137. ISBN 1-84028-152-9. 
  2. ^ A new (2007) Prenocephale skeleton has been discovered in Mongolia, and measures 5.25ft (160cm) in length. This specimen preserves both fore and hindlimb elements, a complete spinal vertebra, tail and ribs. It is a one of a kind specimen that has yet to be described but has been attributed to Prenocephale sp.
  3. ^ Longrich, N.R., Sankey, J. and Tanke, D. (2010). "Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA." Cretaceous Research, . doi:10.1016/j.cretres.2009.12.002
  4. ^ Re: Sphaerotholus
  5. ^ a b Pachycephalosauria
  6. ^ Robert M. Sullivan (2003). "REVISION OF THE DINOSAUR STEGOCERAS LAMBE (ORNITHISCHIA, PACHYCEPHALOSAURIDAE)". of Vertebrate Paleontology: Vol. 23, No. 1, pp. 181–207. 
  7. ^ Dinosaurian Ungulates (Ornithopods)
  8. ^ Evans, D. C.; Schott, R. K.; Larson, D. W.; Brown, C. M.; Ryan, M. J. (2013). "The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs". Nature Communications 4: 1828. doi:10.1038/ncomms2749.  edit

External links[edit]