Macroevolutionary trends in theropod dinosaur feeding mechanics

Waisum Ma; Michael Pittman; Richard J Butler; Stephan Lautenschlager

doi:10.1016/j.cub.2021.11.060

Macroevolutionary trends in theropod dinosaur feeding mechanics

Curr Biol. 2022 Feb 7;32(3):677-686.e3. doi: 10.1016/j.cub.2021.11.060. Epub 2021 Dec 16.

Authors

Waisum Ma¹, Michael Pittman², Richard J Butler³, Stephan Lautenschlager³

Affiliations

¹ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK. Electronic address: w.ma.1@pgr.bham.ac.uk.
² Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK.
³ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.

PMID: 34919807
DOI: 10.1016/j.cub.2021.11.060

Abstract

Theropod dinosaurs underwent some of the most remarkable dietary changes in vertebrate evolutionary history, shifting from ancestral carnivory^1-3 to hypercarnivory⁴^,⁵ and omnivory/herbivory,^6-9 with some taxa eventually reverting to carnivory.^10-12 The mandible is an important tool for food acquisition in vertebrates and reflects adaptations to feeding modes and diets.¹³^,¹⁴ The morphofunctional modifications accompanying the dietary changes in theropod dinosaurs are not well understood because most of the previous studies focused solely on the cranium and/or were phylogenetically limited in scope,¹²^,^15-21 while studies that include multiple clades are usually based on linear measurements and/or discrete osteological characters.⁸^,²² Given the potential relationship between macroevolutionary change and ontogenetic pattern,²³ we explore whether functional morphological patterns observed in theropod mandibular evolution show similarities to the ontogenetic trajectory. Here, we use finite element analysis to study the mandibles of non-avialan coelurosaurian theropods and demonstrate how feeding mechanics vary between dietary groups and major clades. We reveal an overall reduction in feeding-induced stresses along all theropod lineages through time. This is facilitated by a post-dentary expansion and the development of a downturned dentary in herbivores and an upturned dentary in carnivores likely via the "curved bone effect." We also observed the same reduction in feeding-induced stress in an ontogenetic series of jaws of the tyrannosaurids Tarbosaurus and Tyrannosaurus, which is best attributed to bone functional adaptation. This suggests that this common tendency for structural strengthening of the theropod mandible through time, irrespective of diet, is linked to "functional peramorphosis" of bone functional adaptations acquired during ontogeny.

Keywords: diet; dinosaur; feeding mechanics; functional morphology; mesozoic; peramorphosis; skull; vertebrate palaeontology.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Biological Evolution
Carnivory
Dinosaurs* / anatomy & histology
Fossils
Phylogeny
Skull / anatomy & histology