[dinosaur] Forelimb allometry in evolution of non-avian Theropoda (free pdf)

Ben Creisler
[email protected]

A new paper in open access:

José A. Palma Liberona, Sergio Soto-Acuña, Marco A. Mendez & Alexander O.
Vargas (2019)
Assesment and interpretation of negative forelimb allometry in the
evolution of non-avian Theropoda.
Frontiers in Zoology 16:44
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1186_s12983-2D019-2D0342-2D9&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=MlY40mNMf1HOaZtmdz27QWJb2-ypT0DsYUS7XBsXo04&s=Vc_s1PzOdaw1fhXH7UNIfPt4s7kA7myohfyC1CTdS_k&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__link.springer.com_article_10.1186_s12983-2D019-2D0342-2D9&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=MlY40mNMf1HOaZtmdz27QWJb2-ypT0DsYUS7XBsXo04&s=3aUcsRgjSL6NpHhQKon4OnuqqHKJGecQTQAGPnBEx3k&e= 
Also:
https://urldefense.proofpoint.com/v2/url?u=https-3A__frontiersinzoology.biomedcentral.com_articles_10.1186_s12983-2D019-2D0342-2D9&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=MlY40mNMf1HOaZtmdz27QWJb2-ypT0DsYUS7XBsXo04&s=VqGgwsc8aXq-DF1DbHIyqAHAa8M0ErdroN1YSnTakjw&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__link.springer.com_content_pdf_10.1186-252Fs12983-2D019-2D0342-2D9.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=MlY40mNMf1HOaZtmdz27QWJb2-ypT0DsYUS7XBsXo04&s=7iXkXE_GPoATku4XfanK-2-CgfyUXw9cdqiRsHZ3Uhc&e= 

Background

The origin of birds is marked by a significant decrease in body size along
with an increase in relative forelimb size. However, before the evolution
of flight, both traits may have already been related: It has been proposed
that an evolutionary trend of negative forelimb allometry existed in
non-avian Theropoda, such that larger species often have relatively shorter
forelimbs. Nevertheless, several exceptions exist, calling for rigorous
phylogenetic statistical testing.

Results

Here, we re-assessed allometric patterns in the evolution of non-avian
theropods, for the first time taking into account the non-independence
among related species due to shared evolutionary history.
We confirmed a main evolutionary trend of negative forelimb allometry for
non-avian Theropoda, but also found support that some specific subclades
(Coelophysoidea, Ornithomimosauria, and Oviraptorosauria) exhibit
allometric trends that are closer to isometry, losing the ancestral
negative forelimb allometry present in Theropoda as a whole.

Conclusions

Explanations for negative forelimb allometry in the evolution of non-avian
theropods have not been discussed, yet evolutionary allometric trends often
reflect ontogenetic allometries, which suggests negative allometry of the
forelimb in the ontogeny of most non-avian theropods. In modern birds,
allometric growth of the limbs is related to locomotor and behavioral
changes along ontogeny. After reviewing the evidence for such changes
during the ontogeny of non-avian dinosaurs, we propose that proportionally
longer arms of juveniles became adult traits in the small-sized and
paedomorphic Aves.

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