Paraplacodus and the phylogeny of the Placodontia (Reptilia : Sauropterygia)

Authors
Citation
O. Rieppel, Paraplacodus and the phylogeny of the Placodontia (Reptilia : Sauropterygia), ZOOL J LINN, 130(4), 2000, pp. 635-659
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences
Journal title
ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
ISSN journal
0024-4082 → ACNP
Volume
130
Issue
4
Year of publication
2000
Pages
635 - 659
Database
ISI
SICI code
0024-4082(200012)130:4<635:PATPOT>2.0.ZU;2-K
Abstract
The skeletal anatomy of Paraplacodus broilii Peyer from the Grenzbitumen-ho rizon (Anisian-Ladinian boundary) of Monte San Giorgio (Switzerland) is des cribed and compared with that of other placodonts. Paraplacodus is found to share a number of potential synapomorphies with Placodus which could poten tially corroborate the monophyly of the Placodontoidea, but Placodus also s hares an number of potential synapomorphies with the armored placodonts (Cy amodontoidea) which are absent in Paraplacodus. Parsimony analysis rejects the monophyly of the Placodontoidea, and places Paraplacodus at the root of the placodont tree, as the sister-taxon of all the other representatives o f the clade. This correlates with a configuration of the temporal region of the skull that suggest the loss of the lower temporal arch in a diapsid sk ull. The loss of the lower temporal arch is therefore recognized as a sauro pterygian synapomorphy, and might even be a lepidosauromorph synapomorphy. (C) 2000 The Linnean Society of London.