title: Topology, divergence dates, and macroevolutionary inferences vary between different tip-dating approaches applied to fossil theropods (Dinosauria).
abstract: Dated phylogenies of fossil taxa allow palaeobiologists to estimate the timing of major divergences and placement of extinct lineages, and to test macroevolutionary hypotheses. Recently developed Bayesian 'tip-dating' methods simultaneously infer and date the branching relationships among fossil taxa, and infer putative ancestral relationships. Using a previously published dataset for extinct theropod dinosaurs, we contrast the dated relationships inferred by several tip-dating approaches and evaluate potential downstream effects on phylogenetic comparative methods. We also compare tip-dating analyses to maximum-parsimony trees time-scaled via alternative a posteriori approaches including via the probabilistic cal3 method. Among tip-dating analyses, we find opposing but strongly supported relationships, despite similarity in inferred ancestors. Overall, tip-dating methods infer divergence dates often millions (or tens of millions) of years older than the earliest stratigraphic appearance of that clade. Model-comparison analyses of the pattern of body-size evolution found that the support for evolutionary mode can vary across and between tree samples from cal3 and tip-dating approaches. These differences suggest that model and software choice in dating analyses can have a substantial impact on the dated phylogenies obtained and broader evolutionary inferences.
authors.affiliation: Department of Geology University of California Davis, One Shields Avenue Davis, CA 94568, USA Geological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA dwbapst@gmail.com.
authors.forename: D W
authors.identifier: 0000-0002-9087-1103
authors.initials: DW
authors.lastname: Bapst
authors.affiliation: Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Wright
authors.affiliation: Division of Evolution, Ecology, and Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: N J
authors.identifier: 0000-0002-8698-7656
authors.initials: NJ
authors.lastname: Matzke
authors.affiliation: Department of Biological Sciences, Faculty of Science, Macquarie University, Sydney, New South Wales 2109, Australia.
authors.forename: G T
authors.initials: GT
authors.lastname: Lloyd
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D005075:Biological Evolution; D049628:Body Size; D025061:Dinosaurs / Q000145:classification*; D005580:Fossils; D008962:Models, Theoretical; D010802:Phylogeny
keywords: divergence dates; phylogenetic comparative methods; theropods; tip-dating