| Prenocephale | |
|---|---|
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| Holotype skull ZPAL MgD-I/104 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Pachycephalosauria |
| Family: | †Pachycephalosauridae |
| Subfamily: | †Pachycephalosaurinae |
| Genus: | †Prenocephale Maryańska & Osmólska, 1974[1] |
| Species | |
| Synonyms | |
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Prenocephale (meaning "sloping head"[1]) is agenus of smallpachycephalosauriddinosaur from theLate CretaceousNemegt Formation ofMongolia. It was similar in many ways to its close relative,Homalocephale.
The holotype specimen,Z. Pal. No. MgD-I/104, consists of an isolated yet well-preserved skull, dorsal vertebrae and ribs, sacrum, femora, and caudal vertebrae. It was discovered by the Polish-Mongolian Paleontological Expedition and was found at the Nemegt locality, in a sandstone layer of theNemegt Formation.[1] Additional specimens have been recovered from the Bügiin Tsav, Guriliin Tsav, and Tsaagan Khushuu localities of the formation.[2]
AdultPrenocephale measured 2.2 m (7.2 ft) in length and 40 kg (88 lb) in body mass.[3] Unlike the flattened wedge-shaped skull ofHomalocephale (a possible juvenile trait also potentially seen in early growth stages ofPachycephalosaurus), the head ofPrenocephale was rounded and sloping. The dome had a row of small bony spikes and bumps.[4]
Like some other pachycephalosaurs,Prenocephale is known only from skulls and a few other small bones. For this reason, reconstructions usually depictPrenocephale as sharing the basic body plan common to all of the otherPachycephalosauria: a stout body with a short, thick neck, short forelimbs and tall hind legs.
The head ofPrenocephale was comparable to that ofStegoceras, albeit with closed supratemporal fenestrae. Also, the paired grooves above the supraorbitals/prefrontals (along with a posteriorparietal that restricts the frontal dome) are absent inPrenocephale. This differentiates the species fromStegoceras, as such features are common in the latter.
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Prenocephale is a member of thePachycephalosauria, a largeclade of herbivorous/omnivorous dinosaurs from the Late Cretaceous. Robert Sullivan consideredForaminacephale,"Prenocephale" edmontonensis, andSphaerotholus goodwini to form a clade with the Asian taxonP. prenes. He consideredTylocephale the sister taxon to thePrenocephaleclade, while sinkingSphaerotholus buchholtzae as a subjectivejunior synonym of"P." edmontonensis. They all possess a distinct row of nodes on thesquamosal and parietal areas of the skull roof.[5] However, Longrich et al. (2010) and Schott and Evans (2016) keptSphaerotholus as a distinct genus based on cladistic analysis.[6][7]
Homalocephale has been viewed as a possible juvenile ofPrenocephale due to the lack of a dome and its discovery in the same location and chronological interval, but new specimens ofPrenocephale, including a juvenile specimen, suggest thatHomalocephale, even if its holotype is a juvenile, is distinct.[2]
Below is acladogram modified from Evanset al., 2013.[8]
Prenocephale lived in what is now theNemegt Formation, in high upland forests, not the dry deserts ofMongolia nowadays.[9]
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