Meeting Abstract

S3-1.2  Saturday, Jan. 5  Diversity and Disparity of the vertebrate feeding apparatus across the invasion of land ANDERSON, P*; FRIEDMAN, M; RUTA, M; Univ. of Massachusetts, Amherst; Univ. of Oxford, UK; Univ. of Lincoln, UK panderson@bio.umass.edu

When vertebrates first colonized land, about 370 Mya, they encountered a world full of new dietary resources requiring radical changes in feeding mechanisms, not only at the water-land transition but also within the terrestrial realm. However, recent work has indicated that the earliest known limbed vertebrates had mechanical jaw systems similar to their fish relatives. Here, we extend the scope of initial inquiries by examining the functional spectrum of feeding modes in a diverse range of mostly Paleozoic, semi-terrestrial and terrestrial early tetrapods. We collected various biomechanically relevant metrics from the lower jaws of a set of Devonian-Permian taxa: stem-tetrapods (including fishes), stem-amphibians, stem-amniotes, and crown-amniotes. These data were used to construct a morphofunctional space illustrating the variety of biomechanical profiles explored by these early tetrapods. Relative disparity and morphospace occupation across taxonomic groups and stratigraphic bins document a stepwise occupation of various feeding guilds. In terms of mechanical feeding diversity, Devonian and Carboniferous stem tetrapods differ little from lobe-finned fishes. It was not until the appearance of Carboniferous and Permian stem amphibians and amniotes that terrestrial vertebrates began to expand into new regions of biomechanical morphospace. Our data support the hypothesis of a lag in the origin of tetrapod herbivory; the first excursion into herbivore-guild space does not occur until the latest Carboniferous. These results suggest that the conquest of land was a protracted event, lasting 80 My, during which vertebrates developed the repertoire of jaw mechanics necessary to fully exploit available terrestrial resources.