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| The animal responsible for Dromaeosauriformipes rarus tracks is believed to be a small microraptorine related to the ancestors of birds. in Dececchi, Kim, Lockley, Larsson, Holtz, Farlow et Pittman, 2024. artwork: Julius Csotonyi. |
Abstract
Body fossils set limits on feasible reconstructions of functional capacity and behavior in theropod dinosaurs, but do not document in-life behaviors. In contrast, trace fossils such as footprints preserve in-life behaviors that can potentially test and enhance existing reconstructions. Here, we demonstrate how theropod trackways can be used as indirect evidence of pre-avian aerial behavior, expanding the approaches available to study vertebrate flight origins. This involved exploring the behavioral implications of a two-toed Cretaceous-aged theropod trackway produced by a small, bird-like microraptorine moving at high speed. Applying first principle running biomechanics, we were able to conclude that the trackway is atypical, indirectly evidencing pre-avian aerial behavior. This trackway documents the evidence of wing-assisted aerodynamic force production during locomotion, supporting a broader distribution of this behavior than currently known. These findings support previously proposed aerial behavior in early bird-like theropods, showing how trackways will help to deepen our understanding of theropod flight origins.
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| Illustrated reconstruction of Dromaeosauriformipes rarus running along the muddy shore of an ancient lake. artwork: Alex Boersma |
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| The animal responsible for Dromaeosauriformipes rarus tracks is believed to be a small microraptorine related to the ancestors of birds. artwork: Julius Csotonyi. |
T. Alexander Dececchi, Kyung Soo Kim, Martin G. Lockley, Hans C.E. Larsson, Thomas R. Holtz Jr., James O. Farlow and Michael Pittman. 2024. Theropod Trackways as indirect evidence of Pre-avian Aerial Behavior. PNAS. 121 (44) e2413810121. DOI: doi.org/10.1073/pnas.2413810121
Researchers Solve Mystery of ‘Dinky’ Dinosaur’s Unusually Long Stride
UMD paleontologist Thomas R. Holtz Jr. helped recreate the movements of a bird-sized raptor, shedding new light on the origin of flight.
