Short one today
on a small taxon with a nearly equilateral skull in dorsal view, Laidleria gracilis (Fig.1).
Laidleria gracilis (Kitching 1957; Warren 1998; Early Triassc) Originally considered a trematosaur and long considered an enigma taxon, Lairleria was a small, flat head, wide-body, late-surviving, basal dvinosaur with a trinagular skull in dorsal view. Apparently the intertemporals, prefrontals and an interfrontal were overlooked by Warren 1998. If not their fusion to neighboring bones is an autapomorphy.
A close relative, Uruyiella,
(Piiñeiro, Marsicano and Lorenzo 2007), nests these two taxa in a new clade, Laidleriidae. They report, “The Plagiosauridae and the Laidleriidae form a clade at the base of Dvinosauria, which is the sister group of a clade that includes Stereospondyli and Archegosauroidea.” The large reptile tree (LRT, 1426 taxa) agrees with this nesting.
The interesting thing about this specimen
and its sisters is the lack of fossil fingers and toes. We’ll look at this issue using phylogenetic bracketing soon.
Kitching JW 1978. A new small stereospondylous labyrinthodont from the Triassic beds of South Africa. Palaenotologia Africana 5:67–82.
Piñeiro G, Marscano C and Lorenzo N 2007. A new temnospondyl from the Permo-Triassic Buena Vista Formation of Uruguay. Palaeontology 50(3):627–640.
Warren A 1998. Laidleria uncovered: a redescription of Laidleria gracilis Kitching (1975), a temnospondyl from the Cynognathus Zone of South Africa. Zoological Journal of the Linnean Society. 122 (1–2): 167–185.