Anomodonts are a group of non-mammalian synapsids (“mammal-like reptiles”) that represents the dominant herbivores of their time. Their great taxonomic and morphological diversity, unparalleled by any other clade of Permian-Triassic terrestrial tetrapods, is well documented by a cosmopolitan fossil record. In addition, anomodonts survived the most severe extinction event in Earth’s history at the end of the Permian and experienced a second diversification in the Triassic. Thus, they are an ideal clade to investigate macroevolutionary patterns and play an important role in evaluating the impact of the end-Permian extinction on the terrestrial realm.
This work combines descriptive, phylogenetic, and quantitative approaches to study evolutionary patterns of anomodonts with special focus on diversity patterns through time. A taxonomic revision of the Late Permian dicynodont genus Emydops reflects the necessity for a solid taxonomic basis for diversity studies. The description of a new species of this genus is combined with a discussion of dental variability and pathology in dicynodont anomodonts. A detailed description of the postcranial anatomy of the basal anomodont Suminia reveals new insights into the early evolution of anomodonts and therapsids in general. Several derived features, in particular in the autopodium, are unique to Suminia and together with a comparative morphometric analysis indicate grasping abilities of this taxon and the earliest evidence for arboreality in the vertebrate fossil record. The cranial anatomy of the Triassic dicynodont Kombuisia is restudied and a phylogenetic evaluation of the survivorship of anomodonts across the Permian-Triassic boundary reveals more surviving lineages than previously recognized. A review of anomodont-bearing tetrapod faunas forms the basis for a faunal similarity analysis that reveals stratigraphic as well as geographic patterns in faunal groupings. The taxonomic diversity of anomodonts reflects three diversifications and subsequent extinctions in the early Middle Permian, the Early Triassic and the mid-late Triassic.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/16754 |
| Date | 19 January 2009 |
| Creators | Fröbisch, Jörg |
| Contributors | Reisz, Robert R. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
| Format | 33031318 bytes, application/pdf |
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