Frederik Spindler

The basal Sphenacodontia – systematic revision and evolutionary implications

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Kurzfassung in Englisch

The presented study comprises a complete morphological and phylotaxonomic revision of basal Sphenacodontia, designated as the paraphyletic ‘haptodontines’. Ianthodon from the Kasimovian is known from newly identified elements, including most of the skull and particular postcrania. This species is determined as the best model for the initial morphology of the Sphenacomorpha (Edaphosauridae and Sphenacodontia). Remarkably older sphenacodontian remains from the Moscovian indicate a derived, though fragmentarily known form, possibly basal Sphenacodontoidea. The genus Haptodus is conclusively revised, including the revalidation of the type species H. baylei from the Artinskian. Haptodus grandis is renamed as Hypselohaptodus, gen. nov. “Haptodus” garnettensis is not monophyletic with Haptodus, moreover the material assigned to it yielded a greater diversity. Thus, its renaming includes Eohaptodus garnettensis, gen. nov., Tenuacaptor reiszi, gen. et spec. nov., and Kenomagnathus scotti, gen. et spec. nov. Along with Ianthodon and the basal edaphosaurid Ianthasaurus, these taxa from a single assemblage are differentiated by dentition and skull proportions, providing a case study of annidation. Since Ianthodon can be excluded from Sphenacomorpha, the larger, stem-based taxon Haptodontiformes is introduced. More derived ‘haptodontines’ apparently form another radiation, named as Pantherapsida. This new taxon includes Cutleria, Tetraceratops, Hypselohaptodus, the Palaeohatteriidae (Pantelosaurus and Palaeohatteria), and the Sphenacodontoidea. The ‘pelycosaur’-therapsid transition is affirmed as a long-term development. An integrative evolutionary hypothesis of basal sphenacodontians is provided, within which the ghost lineage of Early Permian therapsids can be explained by biome shift.

weitere Metadaten

Synapsida, Pelycosauria, Haptodus, Phylogenetik
Synapsida, Pelycosauria, Haptodus, phylogenetics
SWD SchlagwortePermokarbon, Pelycosauria, Fossil, Evolution, Morphologie <Biologie>, Karbon, Osteologie, Paläontologie, Therapsida, Phylogenie, Phylogenetische Systematik
DDC Klassifikation560
HochschuleTU Bergakademie Freiberg
FakultätFakultät für Geowissenschaften, Geotechnik und Bergbau
BetreuerProf. Dr. Jörg Schneider
GutachterProf. Dr. Jörg Schneider
Prof. Dr. Martin Sander
Tag d. Einreichung (bei der Fakultät)30.04.2015
Tag d. Verteidigung / Kolloquiums / Prüfung18.06.2015
Veröffentlichungsdatum (online)09.07.2015
persistente URNurn:nbn:de:bsz:105-qucosa-171748
InhaltsverzeichnisChapter 1 ‘Haptodontines’ re-examined – An Introduction
Chapter 2 New information on the cranial and postcranial anatomy of the early synapsid Ianthodon schultzei (Sphenacomorpha: Sphenacodontia), and its evolutionary significance
Chapter 3 Reviewing the question of the oldest therapsid
Chapter 4 Revision of the genus Haptodus (Synapsida: Haptodontiformes) and evolutionary implications from the Garnett fossil site
Chapter 5 Morphological description and taxonomic status of Palaeohatteria and Pantelosaurus (Synapsida: Sphenacodontia)
Chapter 6 Re-description of Cutleria and Tetraceratops (Synapsida, Sphenacodontia), with implications on the radiation of Sphenacodontoidea
Chapter 7 Callibrachion and Datheosaurus, two historical and previously mistaken basal Caseasauria (Synapsida) from Europe
Chapter 8 Synthesis and perspective

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