Theropod trackways as indirect evidence of pre-avian aerial behavior

Open access:
https://www.pnas.org/doi/10.1073/pnas.2413810121

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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Op 27-10-2024 om 14:32 schreef John Harshman:

On 10/27/24 1:37 AM, Pandora wrote:

Theropod trackways as indirect evidence of pre-avian aerial behavior

Open access:
https://www.pnas.org/doi/10.1073/pnas.2413810121

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.

Is this really telling us about the origin of flight? Does a running
takeoff from the ground support a ground-up origin of flight?

It's suggestive, but the authors state they "cannot make any claim
linking a specific aerial behavior to the trackway (e.g., launch,
landing, accelerated downward glides, or wing-assisted stride extension)"
If it was landing the critter could have come down from the trees.

And are the tracks really diagnostic at the subfamily level?

See:

https://www.nature.com/articles/s41598-018-35289-4

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