The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.

The scant fossil record of caecilians has obscured the origin and evolution of this lissamphibian group. Eocaecilia micropodia from the Lower Jurassic of North America remains the only stem-group caecilian with an almost complete skull preserved. However, this taxon has been controversial, engenderi...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Hillary C Maddin, Farish A Jenkins, Jason S Anderson
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/dead13d1a8934ad7bbbc027965610ee4
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:dead13d1a8934ad7bbbc027965610ee4
record_format	dspace
spelling	oai:doaj.org-article:dead13d1a8934ad7bbbc027965610ee42021-11-18T08:06:17ZThe braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.1932-620310.1371/journal.pone.0050743https://doaj.org/article/dead13d1a8934ad7bbbc027965610ee42012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23227204/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203The scant fossil record of caecilians has obscured the origin and evolution of this lissamphibian group. Eocaecilia micropodia from the Lower Jurassic of North America remains the only stem-group caecilian with an almost complete skull preserved. However, this taxon has been controversial, engendering re-evaluation of traits considered to be plesiomorphic for extant caecilians. Both the validity of the placement of E. micropodia as a stem caecilian and estimates of the plesiomorphic condition of extant caecilians have been questioned. In order to address these issues, the braincase of E. micropodia was examined via micro-computed tomography. The braincase is considered to be a more reliable phylogenetic indicator than peripheral regions of the skull. These data reveal significant new information, including the possession of an ossified nasal septum, ossified anterior wall of the sphenethmoid, long anterolateral processes on the sphenethmoid, and paired olfactory nerve foramina, which are known only to occur in extant caecilians; the latter are possibly related to the evolution of the tentacle, a caecilian autapomorphy. A phylogenetic analysis that included 64 non-amniote taxa and 308 characters represents the first extensive test of the phylogenetic affinities of E. micropodia. The results place E. micropodia securely on the stem of extant caecilians, representing a clade within Temnospondyli that is the sister taxon to batrachians plus Gerobatrachus. Ancestral character state reconstruction confirms the braincase of E. micropodia to be largely representative of the plesiomorphic condition of extant caecilians. Additionally, the results refine the context within which the evolution of the caecilian form can be evaluated. The robust construction and pattern of the dermal skull of E. micropodia is interpreted as symplesiomorphic with advanced dissorophoid temnospondyls, rather than being autapomorphic in its robust construction. Together these data increase confidence in incorporating E. micropodia into discussions of caecilian evolution.Hillary C MaddinFarish A JenkinsJason S AndersonPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 12, p e50743 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Hillary C Maddin Farish A Jenkins Jason S Anderson The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
description	The scant fossil record of caecilians has obscured the origin and evolution of this lissamphibian group. Eocaecilia micropodia from the Lower Jurassic of North America remains the only stem-group caecilian with an almost complete skull preserved. However, this taxon has been controversial, engendering re-evaluation of traits considered to be plesiomorphic for extant caecilians. Both the validity of the placement of E. micropodia as a stem caecilian and estimates of the plesiomorphic condition of extant caecilians have been questioned. In order to address these issues, the braincase of E. micropodia was examined via micro-computed tomography. The braincase is considered to be a more reliable phylogenetic indicator than peripheral regions of the skull. These data reveal significant new information, including the possession of an ossified nasal septum, ossified anterior wall of the sphenethmoid, long anterolateral processes on the sphenethmoid, and paired olfactory nerve foramina, which are known only to occur in extant caecilians; the latter are possibly related to the evolution of the tentacle, a caecilian autapomorphy. A phylogenetic analysis that included 64 non-amniote taxa and 308 characters represents the first extensive test of the phylogenetic affinities of E. micropodia. The results place E. micropodia securely on the stem of extant caecilians, representing a clade within Temnospondyli that is the sister taxon to batrachians plus Gerobatrachus. Ancestral character state reconstruction confirms the braincase of E. micropodia to be largely representative of the plesiomorphic condition of extant caecilians. Additionally, the results refine the context within which the evolution of the caecilian form can be evaluated. The robust construction and pattern of the dermal skull of E. micropodia is interpreted as symplesiomorphic with advanced dissorophoid temnospondyls, rather than being autapomorphic in its robust construction. Together these data increase confidence in incorporating E. micropodia into discussions of caecilian evolution.
format	article
author	Hillary C Maddin Farish A Jenkins Jason S Anderson
author_facet	Hillary C Maddin Farish A Jenkins Jason S Anderson
author_sort	Hillary C Maddin
title	The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
title_short	The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
title_full	The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
title_fullStr	The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
title_full_unstemmed	The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.
title_sort	braincase of eocaecilia micropodia (lissamphibia, gymnophiona) and the origin of caecilians.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/dead13d1a8934ad7bbbc027965610ee4
work_keys_str_mv	AT hillarycmaddin thebraincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians AT farishajenkins thebraincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians AT jasonsanderson thebraincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians AT hillarycmaddin braincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians AT farishajenkins braincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians AT jasonsanderson braincaseofeocaeciliamicropodialissamphibiagymnophionaandtheoriginofcaecilians
_version_	1718422261283684352

The braincase of Eocaecilia micropodia (Lissamphibia, Gymnophiona) and the origin of Caecilians.

Ejemplares similares