Nedoceratops
Nedoceratops | |
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Skull from multiple angles | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | †Ornithischia |
Clade: | †Ceratopsia |
Family: | †Ceratopsidae |
Subfamily: | †Chasmosaurinae |
Tribe: | †Triceratopsini |
Genus: | †Nedoceratops Ukrainsky, 2007 |
Species: | †N. hatcheri
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Binomial name | |
†Nedoceratops hatcheri (Lull vide Hatcher, 1905)
Originally Diceratops, preoccupied by Förster, 1868 | |
Synonyms | |
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Nedoceratops (meaning "insufficient horned face") is a controversial
History of discovery
The nearly complete skull
The paper that described Nedoceratops was originally part of
Since the Diceratops paper had been written by Hatcher, and Lull had only contributed the name and published the paper after Hatcher's death, Lull was not quite as convinced of the distinctiveness of Diceratops, thinking it primarily
Because the Diceratops name was already in use for a
Nedoceratops means "insufficient horned face". The "nedo" is the Russian prefix meaning "insufficient". The suffix "ceratops", common among ceratopsians, means "horned face". It was named in reference to its lack of a nasal horn.
Description
The nearly complete skull known as USNM 2412 is the only fossil attributed to Nedoceratops hatcheri.[8] Superficially, it resembles that of Triceratops, but on closer examination, it differs: specifically, the brow horns stand almost vertically compared to typical Triceratops skulls, and there also are several holes in the frill (a unique feature of Triceratops proper is that it has a solid, unperforated fill). However, at least some of these holes show evidence that they are the result of injury or disease.[9] The nasal horn of this specimen is low and rounded, compared with the larger, pointed nose horns of typical Triceratops specimens,[2] though this feature appears to be within the known range of individual variation for Triceratops.[10]
Classification
The type species is Nedoceratops hatcheri. Nedoceratops belonged to the Ceratopsia (the name is Latinised Greek for "horned faces"), a group of herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Cretaceous Period, which ended roughly 66 million years ago. All ceratopsians became extinct at the end of this era.[2]
Several authors have suggested that Nedoceratops may be directly ancestral to Triceratops, or perhaps its nearest relative. An ongoing debate concerns the status of Triceratops,
Another supposed difference between Nedoceratops and fossils referred to Triceratops horridus is the remarkably short, rounded nasal "horn". Scanella and Horner proposed that the nasal horn of the USNM 2412 skull could have been lost when the animal was alive or when it became fossilized.[8] However, it has been noted the horns of ceratopsids show a great deal of variation between age groups and individuals, and some specimens more solidly attributed to T. horridus have a similar nasal horn shape. In most features- the short, saddle-shape frill, the s-shaped snout- the animal closely resembles Triceratops horridus.[12]
It has been noted that many of the features that seem to separate Nedoceratops from Triceratops, and specifically Triceratops horridus, may be the result of pathology, injury, and/or deformation of the skull after burial. Two of the features that have been used to diagnose Nedoceratops - the position of the squamosal, and the upright brow horns- are seen on one side of the skull, but not the other. This, along with the fact that the entire skull can be seen to be twisted when seen head-on, have been used to argue that these features result from post-mortem distortion of the fossil, rather than reflecting the anatomy of the animal during life. Furthermore, the presence of numerous holes in the frill suggests pathology due to injury or illness, the supposedly unique 'parietal fenestrae' may therefore be the result of an injury. Tanke & Farke (2007) noted that the supposed parietal fenestra had an irregular shape with swollen margins and an irregularly vascularized texture. This is similar to a parietal hole, also interpreted as the result of an injury by Marshall & Barreto (2001), in a specimen of Torosaurus.[9] The frill is only preserved on one side, which makes it difficult to test this hypothesis.
References
- ^ Black, Riley. "Nedoceratops: To Be, or Not to Be?". Smithsonian Magazine. Retrieved 11 March 2011.
- ^ PMID 21283763.
- .
- .
- ^ Ukrainsky, A.S. (2007). "A new replacement name for Diceratops Lull, 1905 (Reptilia: Ornithischia: Ceratopsidae)." Zoosystematica Rossica, 16(2), 20 December 2007: 292.
- S2CID 86021954.
- ^ Ukrainsky, A.S. (2009). "Sinonimiya rodov Nedoceratops Ukrainsky, 2007 i Diceratus Mateus, 2008 (Reptilia: Ornithischia: Ceratopidae)." Paleontologicheskii zhurnal, 2009(1): 108. Translated as: Ukrainsky, A.S. (2009). "Synonymy of the genera Nedoceratops Ukrainsky, 2007 and Diceratus Mateus, 2008 (Reptilia: Ornithischia: Ceratopidae)." Paleontological Journal, 2009 43(1):116.
- ^ S2CID 86767957.
- ^ PMID 30002987.
- ^ PMID 24303058.
- ^ PMID 22194891.
- .