The Taxonomy, Morphology, and Evolution of Total Group Lissamphibia

Abstract

Temnospondyls are a diverse clade of tetrapods that originated in the Carboniferous represented by a global fossil record. They are hypothesized to include modern amphibians, establishing them as an important clade that is critical for studying evolutionary and ecological context surrounding the origins of modern amphibians. The discourse surrounding their origin has largely hinged on the discovery of new lissamphibian fossils, but valuable information can continue to be gleaned from stem-lissamphibian temnospondyls. Using comparative anatomical methods and phylogenetic analysis, I provide novel commentary on stem-lissamphibian morphology and ecology across the description of three new species of Permo-Triassic temnospondyls and a macroevolutionary analysis of temnospondyl body size evolution.

In my dissertation, I explore the taxonomy, morphology, and evolution of total group Lissamphibia through the temnospondyls. First, I describe the presence of a new species of brachyopoid temnospondyl, which offers ecological and paleogeographic insights from overlooked collections of stem-lissamphibians. Then, I describe a new species of temnospondyl, Ninumbeehan dookoodukah, belonging to an enigmatic and diminutive clade, establishing strong evidence of burrowing in stem-lissamphibians and expanding our knowledge of their ecology in Permo-Triassic mega-monsoon cycles. In the last description, I report on Kermitops gratus, a new species of amphibamiform temnospondyl, identifying evidence of ecological partitioning in skull shape among terrestrial amphibamiforms. Finally, I produce a concatenated phylogeny to test for directionality of body size evolution in temnospondyls, shedding light on the interplay of body size and ecology of the lissamphibian lineage. Altogether, these studies significantly contribute to our understanding of temnospondyl morphology and paleoecology, promoting a more informed foundation in the study and discourse of the macroevolutionary and paleoecological context of lissamphibian origins.