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Re: [dinosaur] Heterodontosaurid remains from Cañadón Asfalto Formation, Argentina

It's great to see some more heterodontosaurid material from South
America.  Fascinating though this heterodontosaurid (_Manidens_?) is,
I very much doubt that it was "arboreal".   Aside from some grasping
abilities of the pes, it has the proportions of a cursorial and
terrestrial animal.  And there are more plausible explanations for a
grasping function of the foot other than grasping tree branches.  The
feet could have been used to help dig up roots or tubers.  If this
heterodontosaurid was omnivorous, the feet could have been used to
secure small prey.  The fact that the non-ungual phalangeal
proportions of pedal digit III are similar to those of some
_Microraptor_, archaeopterygid, and confuciusornithid specimens is not
compelling evidence that this heterodontosaurid was arboreal.  The
ternary diagram and PCA analysis puts all these specimens in the
"uncertain" zone, along with extant birds of undetermined habits
and/or that spend time both on the ground and in trees.

On Thu, Jun 30, 2016 at 1:14 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A new paper:
> Marcos G. Becerra, Diego Pol, Oliver W.M. Rauhut and Ignacio A. Cerda (2016)
> New heterodontosaurid remains from the Cañadón Asfalto Formation:
> cursoriality and the functional importance of the pes in small
> heterodontosaurids.
> Journal of Paleontology (advance online publication)
> DOI: 
> https://urldefense.proofpoint.com/v2/url?u=http-3A__dx.doi.org_10.1017_jpa.2016.24&d=DQIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=eZYd5thZ7pmK6fYmOhbaEj5cFq_FwqBZrvM6r-rY8zE&s=sE-XACHJPD5mW8gmJyzuKOWvaTrgoBWhrZSXZ9TC8xM&e=
> https://urldefense.proofpoint.com/v2/url?u=http-3A__journals.cambridge.org_action_displayAbstract-3FfromPage-3Donline-26aid-3D10379665-26fulltextType-3DRA-26fileId-3DS002233601600024X&d=DQIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=eZYd5thZ7pmK6fYmOhbaEj5cFq_FwqBZrvM6r-rY8zE&s=OpbRY5pN8W809Al819MoL7lBa-RFDN5edE_dKXKjI2c&e=
> New ornithischian remains reported here (MPEF-PV 3826) include two complete
> metatarsi with associated phalanges and caudal vertebrae, from the late
> Toarcian levels of the Cañadón Asfalto Formation. We conclude that these
> fossil remains represent a bipedal heterodontosaurid but lack diagnostic
> characters to identify them at the species level, although they probably
> represent remains of Manidens condorensis, known from the same locality.
> Histological features suggest a subadult ontogenetic stage for the
> individual. A cluster analysis based on pedal measurements identifies
> similarities of this specimen with heterodontosaurid taxa and the inclusion
> of the new material in a phylogenetic analysis with expanded character
> sampling on pedal remains confirms the described specimen as a
> heterodontosaurid. Finally, uncommon features of the digits (length
> proportions among nonungual phalanges of digit III, and claw features) are
> also quantitatively compared to several ornithischians, theropods, and
> birds, suggesting that this may represent a bipedal cursorial
> heterodontosaurid with gracile and grasping feet and long digits. In
> particular, the elongated non-terminal pedal phalanges and morphology of
> digit III resemble features present in arboreal birds, a unique condition
> found so far among ornithischians.