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Re: [dinosaur] Dromaeosaurid, troodontid, and other coelurosaur bite mechanics (free pdf)



The authors propose that troodontids might have favored softer and
smaller prey that required lower bite forces or could be swallowed
whole.  This ties in with the work of Fowler et al. (2011
doi:10.1371/journal.pone.0028964) regarding the predatory habits of
derived troodontids inferred from their pedal proportions: "By
comparison [with dromaeosaurids], troodontids instead evolved towards
a more cursorial habit, being fast and nimble with weaker, but quick
feet. The more mobile D-I in troodontids perhaps afforded a more even
grip, better adapted for snatching and subduing smaller prey."  So the
dental evidence fits the hindlimb evidence.

That doesn't leave much of a role for the arms or hands in prey
capture.  Indeed, troodontids tend to have rather short forelimbs.
However, at least one derived troodontid (_Linhevenator_) had a very
robust humerus and a large deltopectoral crest, which suggest its
short arms were quite powerful (Xu et al. 2011
doi:10.1371/journal.pone.0022916).  It may be that strong, feathered
forelimbs were used in vigorous sexual display or combat - as proposed
for the well-muscled caenagnathid _Apatoraptor_ (Funston & Currie 2016
dx.doi.org/10.1080/02724634.2016.1160910).

P.S. Torices &c curiously refer to the troodontid '_Troodon
inequalis_', which in a previous publication was called
_Stenonychosaurus inequalis_ (van der Reest & Currie 2017
dx.doi.org/10.1139/cjes-2017-0031).


On Fri, Apr 27, 2018 at 2:21 AM, Ben Creisler <bcreisler@gmail.com> wrote:
>
> Additional news items and a correction to the citation (adding a direct link
> to the webpage):
>
> Angelica Torices, Ryan Wilkinson, Victoria M. Arbour, Jose Ignacio
> Ruiz-OmeÃaca & Philip J. Currie (2018)
> Puncture-and-Pull Biomechanics in the Teeth of Predatory Coelurosaurian
> Dinosaurs.
> Current Biology (advance online publication)
> DOI: 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1016_j.cub.2018.03.042&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=QYVGfUZxU_LN0CpPx_C2eU8XUjEkiYzbXQG4LC4ccx8&e=
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.cell.com_current-2Dbiology_fulltext_S0960-2D9822-2818-2930371-2D3&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=kqU5R3V8wFlvzgwzkQUKLqIJKliXYIUbv3Q_zfOHu1Q&e=
>
>
> Free pdf:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.cell.com_current-2Dbiology_pdf_S0960-2D9822-2818-2930371-2D3.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=FuYzuSYYry8zBWuglPs6KQnMTUrLFkEL-l71QWE4Cmc&e=
>
>
>
> More news:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.folio.ca_dinosaurs-2Dteeth-2Doffer-2Dclues-2Dto-2Dunderstanding-2Dhow-2Dand-2Dwhat-2Dthey-2Date_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=6W4k9AAtz-Df6Il5EzZzZgbbAaLEzlUMqXefiRNYhBc&e=
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.inverse.com_article_44172-2Ddinosaur-2Dteeth-2Dmicrowear-2Danalysis&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=uI691-1BnBroupSCCCMSJ1Fh8K1PjjOKzWPogGKuULI&e=
>
>
> On Thu, Apr 26, 2018 at 9:11 AM, Ben Creisler <bcreisler@gmail.com> wrote:
>>
>>
>>
>>
>> Ben Creisler
>> bcreisler@gmail.com
>>
>>
>> A new paper. The pdf is free for now...
>>
>>
>> Angelica Torices, Ryan Wilkinson, Victoria M. Arbour, Jose Ignacio
>> Ruiz-OmeÃaca & Philip J. Currie (2018)
>> Puncture-and-Pull Biomechanics in the Teeth of Predatory Coelurosaurian
>> Dinosaurs.
>> Current Biology (advance online publication)
>> DOI: 
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1016_j.cub.2018.03.042&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=QYVGfUZxU_LN0CpPx_C2eU8XUjEkiYzbXQG4LC4ccx8&e=
>>
>>
>> Free pdf:
>>
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.cell.com_current-2Dbiology_pdf_S0960-2D9822-2818-2930371-2D3.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=FuYzuSYYry8zBWuglPs6KQnMTUrLFkEL-l71QWE4Cmc&e=
>>
>>
>> Highlights
>>
>> Theropods used puncture-and-pull feeding movements, based on microwear
>> analyses
>> Troodontid teeth were most likely to fail at non-optimal bite angles
>> Troodontids may have favored prey requiring lower bite forces than
>> dromaeosaurids
>>
>> Summary
>>
>> The teeth of putatively carnivorous dinosaurs are often blade-shaped with
>> well-defined serrated cutting edges (Figure 1). These ziphodont teeth are
>> often easily differentiated based on the morphology and density of the
>> denticles. A tearing function has been proposed for theropod denticles in
>> general, but the functional significance of denticle phenotypic variation
>> has received less attention. In particular, the unusual hooked denticles
>> found in troodontids suggest a different feeding strategy or diet compared
>> to other small theropods. We used a two-pronged approach to investigate the
>> function of denticle shape variation across theropods with both congruent
>> body shapes and sizes (e.g., dromaeosaurids versus troodontids) and highly
>> disparate body shapes and sizes (e.g., troodontids versus tyrannosaurids),
>> using microwear and finite element analyses (Figure 1). We found that many
>> toothed coelurosaurian theropods employed a puncture-and-pull feeding
>> movement, in which parallel scratches form while biting down into prey and
>> oblique scratches form as the head is pulled backward with the jaws closed.
>> In finite element simulations, theropod teeth had the lowest stresses when
>> bite forces were aligned with the oblique family of microwear scratches.
>> Different denticle morphologies performed differently under a variety of
>> simulated biting angles: Dromaeosaurus and Saurornitholestes were
>> well-adapted for handling struggling prey, whereas troodontid teeth were
>> more likely to fail at non-optimal bite angles. Troodontids may have favored
>> softer, smaller, or immobile prey.
>>
>>
>> ==
>>
>>
>> News:
>>
>>
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__phys.org_news_2018-2D04-2Ddinosaurs-2Dtooth-2Dpredatory.html&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=pJ4LKUYCNTUrwJvLmgyIH7WZXz-9JHAeGnrM97jLMzc&s=jVKfjKEx5PBv4-d_urgm90959c2bVKxQSNqq20jRjHM&e=
>>
>