Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.

<h4>Background</h4>The validity of Nedoceratops hatcheri, a chasmosaurine ceratopsid dinosaur known from a single skull recovered in the Lance Formation of eastern Wyoming, U.S.A., has been debated for over a century. Some have argued that the taxon is an aberrant Triceratops, and most r...

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Autor principal:	Andrew A Farke
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2011
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/f6e4a7fcde3a4656a6351671ac9abff7
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spelling	oai:doaj.org-article:f6e4a7fcde3a4656a6351671ac9abff72021-11-18T07:00:11ZAnatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.1932-620310.1371/journal.pone.0016196https://doaj.org/article/f6e4a7fcde3a4656a6351671ac9abff72011-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21283763/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>The validity of Nedoceratops hatcheri, a chasmosaurine ceratopsid dinosaur known from a single skull recovered in the Lance Formation of eastern Wyoming, U.S.A., has been debated for over a century. Some have argued that the taxon is an aberrant Triceratops, and most recently it was proposed that N. hatcheri represents an intermediate ontogenetic stage between "young adult" and "old adult" forms of a single taxon previously split into Triceratops and Torosaurus.<h4>Methodology/principal findings</h4>The holotype skull of Nedoceratops hatcheri was reexamined in order to map reconstructed areas and compare the specimen with other ceratopsids. Although squamosal fenestrae are almost certainly not of taxonomic significance, some other features are unique to N. hatcheri. These include a nasal lacking a recognizable horn, nearly vertical postorbital horncores, and relatively small parietal fenestrae. Thus, N. hatcheri is tentatively considered valid, and closely related to Triceratops spp. The holotype of N. hatcheri probably represents an "old adult," based upon bone surface texture and the shape of the horns and epiossifications on the frill. In this study, Torosaurus is maintained as a genus distinct from Triceratops and Nedoceratops. Synonymy of the three genera as ontogenetic stages of a single taxon would require cranial changes otherwise unknown in ceratopsids, including additions of ossifications to the frill and repeated alternation of bone surface texture between juvenile and adult morphotypes.<h4>Conclusions/significance</h4>Triceratops, Torosaurus, and likely Nedoceratops, are all distinct taxa, indicating that species richness for chasmosaurine ceratopsids in the Lance Formation just prior to the Cretaceous-Paleocene extinction was roughly equivalent to that earlier in the Cretaceous.Andrew A FarkePublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 6, Iss 1, p e16196 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Andrew A Farke Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
description	<h4>Background</h4>The validity of Nedoceratops hatcheri, a chasmosaurine ceratopsid dinosaur known from a single skull recovered in the Lance Formation of eastern Wyoming, U.S.A., has been debated for over a century. Some have argued that the taxon is an aberrant Triceratops, and most recently it was proposed that N. hatcheri represents an intermediate ontogenetic stage between "young adult" and "old adult" forms of a single taxon previously split into Triceratops and Torosaurus.<h4>Methodology/principal findings</h4>The holotype skull of Nedoceratops hatcheri was reexamined in order to map reconstructed areas and compare the specimen with other ceratopsids. Although squamosal fenestrae are almost certainly not of taxonomic significance, some other features are unique to N. hatcheri. These include a nasal lacking a recognizable horn, nearly vertical postorbital horncores, and relatively small parietal fenestrae. Thus, N. hatcheri is tentatively considered valid, and closely related to Triceratops spp. The holotype of N. hatcheri probably represents an "old adult," based upon bone surface texture and the shape of the horns and epiossifications on the frill. In this study, Torosaurus is maintained as a genus distinct from Triceratops and Nedoceratops. Synonymy of the three genera as ontogenetic stages of a single taxon would require cranial changes otherwise unknown in ceratopsids, including additions of ossifications to the frill and repeated alternation of bone surface texture between juvenile and adult morphotypes.<h4>Conclusions/significance</h4>Triceratops, Torosaurus, and likely Nedoceratops, are all distinct taxa, indicating that species richness for chasmosaurine ceratopsids in the Lance Formation just prior to the Cretaceous-Paleocene extinction was roughly equivalent to that earlier in the Cretaceous.
format	article
author	Andrew A Farke
author_facet	Andrew A Farke
author_sort	Andrew A Farke
title	Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
title_short	Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
title_full	Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
title_fullStr	Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
title_full_unstemmed	Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.
title_sort	anatomy and taxonomic status of the chasmosaurine ceratopsid nedoceratops hatcheri from the upper cretaceous lance formation of wyoming, u.s.a.
publisher	Public Library of Science (PLoS)
publishDate	2011
url	https://doaj.org/article/f6e4a7fcde3a4656a6351671ac9abff7
work_keys_str_mv	AT andrewafarke anatomyandtaxonomicstatusofthechasmosaurineceratopsidnedoceratopshatcherifromtheuppercretaceouslanceformationofwyomingusa
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Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the upper Cretaceous Lance Formation of Wyoming, U.S.A.

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