MESSAGE
| DATE | 2016-11-25 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Learn] Fwd: [dinosaur] Flightless theropod phylogenetic variation
|
From learn-bounces-at-nylxs.com Fri Nov 25 16:37:14 2016
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Subject: [Learn] Fwd: [dinosaur] Flightless theropod phylogenetic variation
in hind-limb bone scaling
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-------- Forwarded Message --------
Subject: [dinosaur] Flightless theropod phylogenetic variation in
hind-limb bone scaling
Date: Fri, 25 Nov 2016 11:09:31 -0800
From: Ben Creisler
Reply-To: Ben Creisler
To: dinosaur-l-at-usc.edu
Ben Creisler
bcreisler-at-gmail.com
A new paper:
Nicholas R. Chan (2016)
Phylogenetic variation in hind-limb bone scaling of flightless theropods.
Paleobiology (advance online publication)
DOI:
https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1017_pab.2016.32Published&d=DgIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=ggCQwnOPcmyEb61mJZjRktfXLFKxqy_O7Kt02tNaUUI&s=z7SPPRlgZx7h7T2SldhZ-yD7h0COHPCWQU-hUz7lxOA&e=
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.cambridge.org_core_journals_paleobiology_article_div-2Dclasstitlephylogenetic-2Dvariation-2Din-2Dhind-2Dlimb-2Dbone-2Dscaling-2Dof-2Dflightless-2Dtheropodsdiv_FEA15EC11E3A6D1D15C17F4F18BE6F93&d=DgIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=ggCQwnOPcmyEb61mJZjRktfXLFKxqy_O7Kt02tNaUUI&s=W5m_TH5siBUEZgipfdU-5SJDmFh2aaLNFah0_Qu8g7g&e=
The robusticity of the weight-bearing limbs of large terrestrial animals is
expected to increase at a more rapid rate than in their smaller relatives.
This scaling has been hypothesized to allow large species to maintain
stresses in the limb bones that are similar to those seen in smaller ones.
Curvilinear scaling has previously been found in mammals and nonavian
theropods but has not been demonstrated in birds. In this study, polynomial
regressions of leg-bone length and circumference in terrestrial flightless
birds were carried out to test for a relationship similar to that seen in
nonavian theropods. Flightless birds exhibit curvilinear scaling, with the
femora of large taxa becoming thicker relative to length at a greater rate
than in smaller taxa. Evidence was found for nonlinear scaling in the leg
bones of nonavian theropods. However, unlike in avians, there is also
phylogenetic variation between taxonomic groups, with tyrannosaur leg bones
in particular scaling differently than other groups. Phylogenetically
corrected quadratic regressions and separate analyses of taxonomic
groupings found little phylogenetic variation in flightless birds. It is
suggested here that the nonlinear scaling seen in avian femora is due to
the need to maintain the position of the knee under a more anterior center
of mass, thereby restricting femoral length. The femur of nonavian
theropods is not so constrained, with greater variability of the linear
scaling relationships between clades. Phylogenetic variation in limb-bone
scaling may broaden the errors for mass-predictive scaling equations based
on limb-bone measurements of nonavian theropods.
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