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Re: Dakotadon (Early Cretaceous ornithopod) redescribed

Ben Creisler

The official final version is now out:

Clint A. Boyd and Darrin C. Pagnac (2015)
Insight on the anatomy, systematic relationships, and age of the Early
Cretaceous ankylopollexian dinosaur Dakotadon lakotaensis.
PeerJ 3:e1263
doi: https://dx.doi.org/10.7717/peerj.1263

On Thu, Sep 3, 2015 at 8:12 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> An open access preprint in PeerJ:
> Clint A Boyd and Darrin C Pagnac (2015)
> Insight on the anatomy, systematic relationships, and age of the Early
> Cretaceous ankylopollexian dinosaur Dakotadon lakotaensis.
> PeerJ PrePrints 3:e1649
> doi: https://dx.doi.org/10.7287/peerj.preprints.1135v2
> https://peerj.com/preprints/1135/
> https://peerj.com/preprints/1135.pdf
> Knowledge regarding the early evolution within the dinosaurian clade
> Ankylopollexia drastically increased over the past two decades, in
> part because of an increase in described taxa from the Early
> Cretaceous of North America. These advances motivated the recent
> completion of extensive preparation and conservation work on the
> holotype and only known specimen of Dakotadon lakotaensis, a basal
> ankylopollexian from the Lakota Formation of South Dakota. That
> specimen (SDSM 8656) preserves a partial skull, lower jaws, a single
> dorsal vertebra, and two caudal vertebrae. That new preparation work
> exposed several bones not included in the original description and
> revealed that other bones were previously misidentified. The presence
> of extensive deformation in areas of the skull is also noted that
> influenced inaccuracies in prior descriptions and reconstructions of
> this taxon. In addition to providing an extensive re-description of D.
> lakotaensis, this study reviews previously proposed diagnoses for this
> taxon, identifies two autapomorphies, and provides an extensive
> differential diagnosis. Dakotadon lakotaensis is distinct from the
> only other ankylopollexian taxon known from the Lakota Formation,
> Osmakasaurus depressus, in the presence of two prominent,
> anteroposteriorly oriented ridges on the ventral surfaces of the
> caudal vertebrae, the only overlapping material preserved between
> these taxa. The systematic relationships of D. lakotaensis are
> evaluated using both the parsimony and posterior probability
> optimality criteria, with both sets of analyses recovering D.
> lakotaensis as a non-hadrosauriform ankylopollexian that is more
> closely related to taxa from the Early Cretaceous (e.g.,
> Iguanacolossus, Hippodraco, and Theiophytalia) than to more basally
> situated taxa from the Jurassic (e.g., Camptosaurus, Uteodon). This
> taxonomic work is supplemented by field work that relocated the type
> locality, confirming its provenance from unit L2 (lower Fuson Member
> equivalent) of the Lakota Formation. Those data, combined with
> recently revised ages for the members of the Lakota Formation based on
> charophyte and ostracod biostratigraphy, constrain the age of this
> taxon to the late Valanginian to early Barremian.