[dinosaur] Bony core and keratinous sheath in avian pedal claws (free pdf)

Ben Creisler
[email protected]

A new paper with free pdf (previous preprint version on bioRxiv):


Brandon P. Hedrick,  Samantha A. Cordero, Lindsay E. Zanno, Christopher
Noto & Peter Dodson (2019)
Quantifying shape and ecology in avian pedal claws: The relationship
between the bony core and keratinous sheath.
Ecology and Evolution (advance online publication)
doi:  https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1002_ece3.5507&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=8l3uNx980-AICX1xiAKGSBxHBceOjZwAjx56uZG2Dag&s=LegUvV1yAxbEQO0u-WVYdvd8NTETi36wdqaxb_GB-9s&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_10.1002_ece3.5507&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=8l3uNx980-AICX1xiAKGSBxHBceOjZwAjx56uZG2Dag&s=yRoGt_fud1WcyL2K_TJ1--S-EGh_YnuZN2fWF-a5swY&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_pdf_10.1002_ece3.5507&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=8l3uNx980-AICX1xiAKGSBxHBceOjZwAjx56uZG2Dag&s=x29ZyEBodZ-r7Pamq8p4aOp52UfVpGs-WGslFNpOQN0&e= 


Terrestrial tetrapods use their claws to interact with their environments
in a plethora of ways. Birds in particular have developed a diversity of
claw shapes since they are often not bound to terrestrial locomotion and
have heterogeneous body masses ranging several orders of magnitude.
Numerous previous studies have hypothesized a connection between pedal claw
shape and ecological mode in birds, yet have generated conflicting results,
spanning from clear ecological groupings based on claw shape to a complete
overlap of ecological modes. The majority of these studies have relied on
traditional morphometric arc measurements of keratinous sheaths and have
variably accounted for likely confounding factors such as body mass and
phylogenetic relatedness. To better address the hypothesized relationship
between ecology and claw shape in birds, we collected 580 radiographs
allowing visualization of the bony core and keratinous sheath shape in 21
avian orders. Geometric morphometrics was used to quantify bony core and
keratinous sheath shape and was compared to results using traditional arc
measurements. Neither approach significantly separates bird claws into
coarse ecological categories after integrating body size and phylogenetic
relatedness; however, some separation between ecological groups is evident
and we find a gradual shift from the claw shape of ground‐dwelling birds to
those of predatory birds. Further, the bony claw core and keratinous sheath
are significantly correlated, and the degree of functional integration does
not differ across ecological groups. Therefore, it is likely possible to
compare fossil bony cores with extant keratinous sheaths after applying
corrections. Finally, traditional metrics and geometric morphometric shape
are significantly, yet loosely correlated. Based on these results, future
workers are encouraged to use geometric morphometric approaches to study
claw geometry and account for confounding factors such as body size,
phylogeny, and individual variation prior to predicting ecology in fossil
taxa.

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