Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.

<h4>Background</h4>In horned dinosaurs, taxonomy is complicated by the fact that the cranial ornament that distinguishes species changes with age. Based on this observation, it has been proposed that the genera Triceratops and Torosaurus are in fact synonymous, with specimens identified...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Nicholas R Longrich, Daniel J Field
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/218dfc8d836f4931a8a5f6bb5f781b54
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:218dfc8d836f4931a8a5f6bb5f781b54
record_format	dspace
spelling	oai:doaj.org-article:218dfc8d836f4931a8a5f6bb5f781b542021-11-18T07:26:23ZTorosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.1932-620310.1371/journal.pone.0032623https://doaj.org/article/218dfc8d836f4931a8a5f6bb5f781b542012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22393425/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>In horned dinosaurs, taxonomy is complicated by the fact that the cranial ornament that distinguishes species changes with age. Based on this observation, it has been proposed that the genera Triceratops and Torosaurus are in fact synonymous, with specimens identified as Torosaurus representing the adult form of Triceratops. The hypothesis of synonymy makes three testable predictions: 1) the species in question should have similar geographic and stratigraphic distributions, 2) specimens assigned to Torosaurus should be more mature than those assigned to Triceratops, and 3) intermediates should exist that combine features of Triceratops and Torosaurus. The first condition appears to be met, but it remains unclear whether the other predictions are borne out by the fossil evidence.<h4>Methodology/principal findings</h4>We assessed the relative maturity of Torosaurus and Triceratops specimens by coding skulls for characters that vary with maturity, and then using a clustering analysis to arrange them into a growth series. We found that a well-defined sequence of changes exists in horned dinosaurs: development of cranial ornament occurs in juveniles, followed by fusion of the skull roof in subadults, and finally, the epoccipitals, epijugals, and rostral fuse to the skull in adults. Using this scheme, we identified mature and immature individuals of both Torosaurus and Triceratops. Furthermore, we describe the ventral depressions on the frill of Triceratops, and show that they differ in shape and position from the parietal fenestrae of Torosaurus. Thus, we conclude that these structures are not intermediates between the solid frill of Triceratops and the fenestrated frill of Torosaurus.<h4>Conclusions/significance</h4>Torosaurus is a distinct genus of horned dinosaur, not the adult of Triceratops. Our method provides a framework for assessing the hypothesis of synonymy through ontogeny in the fossil record.Nicholas R LongrichDaniel J FieldPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 2, p e32623 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Nicholas R Longrich Daniel J Field Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
description	<h4>Background</h4>In horned dinosaurs, taxonomy is complicated by the fact that the cranial ornament that distinguishes species changes with age. Based on this observation, it has been proposed that the genera Triceratops and Torosaurus are in fact synonymous, with specimens identified as Torosaurus representing the adult form of Triceratops. The hypothesis of synonymy makes three testable predictions: 1) the species in question should have similar geographic and stratigraphic distributions, 2) specimens assigned to Torosaurus should be more mature than those assigned to Triceratops, and 3) intermediates should exist that combine features of Triceratops and Torosaurus. The first condition appears to be met, but it remains unclear whether the other predictions are borne out by the fossil evidence.<h4>Methodology/principal findings</h4>We assessed the relative maturity of Torosaurus and Triceratops specimens by coding skulls for characters that vary with maturity, and then using a clustering analysis to arrange them into a growth series. We found that a well-defined sequence of changes exists in horned dinosaurs: development of cranial ornament occurs in juveniles, followed by fusion of the skull roof in subadults, and finally, the epoccipitals, epijugals, and rostral fuse to the skull in adults. Using this scheme, we identified mature and immature individuals of both Torosaurus and Triceratops. Furthermore, we describe the ventral depressions on the frill of Triceratops, and show that they differ in shape and position from the parietal fenestrae of Torosaurus. Thus, we conclude that these structures are not intermediates between the solid frill of Triceratops and the fenestrated frill of Torosaurus.<h4>Conclusions/significance</h4>Torosaurus is a distinct genus of horned dinosaur, not the adult of Triceratops. Our method provides a framework for assessing the hypothesis of synonymy through ontogeny in the fossil record.
format	article
author	Nicholas R Longrich Daniel J Field
author_facet	Nicholas R Longrich Daniel J Field
author_sort	Nicholas R Longrich
title	Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
title_short	Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
title_full	Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
title_fullStr	Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
title_full_unstemmed	Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
title_sort	torosaurus is not triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/218dfc8d836f4931a8a5f6bb5f781b54
work_keys_str_mv	AT nicholasrlongrich torosaurusisnottriceratopsontogenyinchasmosaurineceratopsidsasacasestudyindinosaurtaxonomy AT danieljfield torosaurusisnottriceratopsontogenyinchasmosaurineceratopsidsasacasestudyindinosaurtaxonomy
_version_	1718423461960876032

Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy.

Ejemplares similares