Australian Museum Journal The Triassic amphibian Thoosuchus yakovlevi and the relationships of the Trematosauroidea (Temnospondyli: Stereospondyli)

Shortform:
Damiani and Yates, 2003, Rec. Aust. Mus. 55(3): 331–342
Author(s):
Damiani, Ross J.; Yates, Adam M.
Year published:
2003
Title:
The Triassic amphibian Thoosuchus yakovlevi and the relationships of the Trematosauroidea (Temnospondyli: Stereospondyli)
Serial title:
Records of the Australian Museum
Volume:
55
Issue:
3
Start page:
331
End page:
342
DOI:
10.3853/j.0067-1975.55.2003.1388
Language:
English
Date published:
10 December 2003
Cover date:
10 December 2003
ISSN:
0067-1975
CODEN:
RAUMAJ
Publisher:
The Australian Museum
Place published:
Sydney, Australia
Subjects:
PALAEONTOLOGY; TRIASSIC: EARLY; FOSSIL
Digitized:
10 December 2003
Available online:
10 December 2003
Reference number:
1388
EndNote package:
EndNote file
Title page:
Title page (11kb PDF)
Complete work:
Complete work (908kb PDF)

Abstract

A skull of the basal trematosauroid temnospondyl Thoosuchus yakovlevi from the Early Triassic of Russia is described. Characters showing phylogenetic affinities with the Trematosauroidea include the presence of a postorbital-prepineal growth zone, the well-developed sensory sulci, the ventrally knife-edged cultriform process of the parasphenoid, and the posteriorly expanded parasphenoid body. A preliminary phylogenetic analysis of trematosauroid relationships confirms that Benthosuchus is a basal trematosaurian rather than a basal mastodonsauroid, and that Thoosuchus is the sister group to all other trematosauroids. Relationships within the Trematosauroidea are poorly established with as yet little evidence for subdivision of the group as previously proposed. In addition, the hypothesis that the Metoposauroidea is nested within the Trematosauroidea is supported. However, the Trematosauridae sensu stricto appears to be paraphyletic. The basal stereospondyl dichotomy between the Mastodonsauroidea and its relatives (the Capitosauria), and the Trematosauroidea and its relatives (the Trematosauria), is supported, and now seems well established.