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Re: Dakotaraptor holotype is a chimera + first dromaeosaurid from Bayan Gobi Formation



The Dakotaraptor "furcula" paper is now out in official form with some changes:


Victoria M. Arbour, Lindsay E. Zanno, Derek W. Larson, David C. Evans
& Hans-Dieter Sues (2016)
The furculae of the dromaeosaurid dinosaur Dakotaraptor steini are
trionychid turtle entoplastra.
PeerJ 4:e1691
doi: https: // doi.org/10.7717/peerj.1691
https: // peerj.com/articles/1691/



Dakotaraptor steini is a recently described dromaeosaurid dinosaur
from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of
South Dakota. Included within the D. steini hypodigm are three
elements originally identified as furculae, one of which was made part
of the holotype specimen. We show that the elements described as D.
steini ‘furculae’ are not theropod dinosaur furculae, but are rather
trionychid turtle entoplastra referable to cf.Axestemys splendida. The
hypodigm of D. steini should be adjusted accordingly.

On Mon, Dec 7, 2015 at 6:06 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
> New papers in PeerJ:
>
> Victoria M. Arbour, Lindsay E. Zanno, Derek W. Larson, David C. Evans
> & Hans-Dieter Sues (2015)
> The furculae of the dromaeosaurid dinosaur Dakotaraptor steini are
> trionychid turtle entoplastra.
> PeerJ PrePrints 3:e1957
> doi:  
> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.7287_peerj.preprints.1570v1&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=0iY_6BlI6t5a5oliop0VHpzOCf_M-oJFY5rGrNLr_Zw&s=Hs53jATQeWGFFRv1xOaiagibeeih_ObOLA3buxFWj9E&e=
>  
> https://urldefense.proofpoint.com/v2/url?u=https-3A__peerj.com_preprints_1570_&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=0iY_6BlI6t5a5oliop0VHpzOCf_M-oJFY5rGrNLr_Zw&s=hpmj5LfqGSMc7EBWOZWD2DlvWvbPCDBq3Q7w9wVXFdc&e=
>  
>
> Dakotaraptor steini is a recently described dromaeosaurid dinosaur
> from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of
> South Dakota. Included within the D. steini hypodigm are three
> elements originally identified as furculae: one which is part of the
> holotype specimen and two referred specimens. We show that the
> elements described as D. steini ‘furculae’ are not theropod dinosaur
> furculae, but rather trionychid turtle entoplastra. Given that the
> holotype 'furcula' is not referable to Dromaeosauridae and that the
> specimen is a disarticulated individual based on skeletal remains from
> a multitaxic bonebed, the holotype of Dakotaraptor steini is a
> chimera.
>
> ===
>
>
> Official version; was a preprint a few months back
>
> Michael Pittman, Rui Pei, Qingwei Tan & Xing Xu (2015)
> The first dromaeosaurid (Dinosauria: Theropoda) from the Lower
> Cretaceous Bayan Gobi Formation of Nei Mongol, China.
> PeerJ 3:e1480
> doi: 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.7717_peerj.1480&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=0iY_6BlI6t5a5oliop0VHpzOCf_M-oJFY5rGrNLr_Zw&s=0IQKzeXN7ju5T_gg-fS5OAgs32G8eofV4dTHefdOn1k&e=
>  
> https://urldefense.proofpoint.com/v2/url?u=https-3A__peerj.com_articles_1480_&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=0iY_6BlI6t5a5oliop0VHpzOCf_M-oJFY5rGrNLr_Zw&s=y5z54L75a6oX80Jsg13kF2l3nsp4OalcCvHEtREHCfc&e=
>  
>
>
> The first dromaeosaurid theropod from the Lower Cretaceous Bayan Gobi
> Formation is identified based on an incompletely preserved
> partially-articulated left leg, increasing the known diversity of its
> understudied ecosystem. The leg belongs to specimen IVPP V22530 and
> includes a typical deinonychosaurian pedal phalanx II-2 with a
> distinct constriction between the enlarged proximal end and the distal
> condyle as well as a typical deinonychosaurian enlarged pedal phalanx
> II-3. It possesses a symmetric metatarsus and a slender and long MT V
> that together suggest it is a dromaeosaurid. Two anatomical traits
> suggest the leg is microraptorine-like, but a more precise taxonomic
> referral was not possible: metatarsals II, III and IV are closely
> appressed distally and the ventral margin of the medial ligament pit
> of phalanx II-2 is close to the centre of the rounded distal condyle.
> This taxonomic status invites future efforts to discover additional
> specimens at the study locality because—whether it is a microraptorine
> or a close relative—this animal is expected to make important
> contributions to our understanding of dromaeosaurid evolution and
> biology. IVPP V22530 also comprises of an isolated dromaeosaurid
> manual ungual, a proximal portion of a right theropod anterior dorsal
> rib and an indeterminate bone mass that includes a collection of ribs.
> Neither the rib fragment nor the bone mass can be confidently referred
> to Dromaeosauridae, although they may very well belong to the same
> individual to whom the left leg belongs.