Search results

Now showing 1 - 10 of 40
  • Publication
    The Slothful Claw: Osteology and Taphonomy of Nothronychus mckinleyi and N. graffami (Dinosauria: Theropoda) and Anatomical Considerations for Derived Therizinosaurids
    (2015-06-10) Hedrick, Brandon P; Zanno, Lindsay E; Dodson, Peter; Wolfe, Douglas G
    Nothronychus was the first definitive therizinosaurian discovered in North America and currently represents the most specialized North American therizinosaurian genus. It is known from two species, No. mckinleyi from the Moreno Hill Formation (middle Turonian) in west-central New Mexico, and No. graffami from the Tropic Shale (early Turonian) in south-central Utah. Both species are represented by partial to nearly complete skeletons that have helped elucidate evolutionary trends in Therizinosauria. In spite of the biogeographical and evolutionary importance of these two taxa, neither has received a detailed description. Here, we present comprehensive descriptions of No. mckinleyi and No. graffami, the latter of which represents the most complete therizinosaurid skeleton known to date. We amend previous preliminary descriptions of No. mckinleyi and No. graffami based on these new data and modify previous character states based on an in-depth morphological analysis. Additionally, we review the depositional history of both specimens of Nothronychus and compare their taphonomic modes. We demonstrate that the species were not only separated geographically, but also temporally. Based on ammonoid biozones, the species appear to have been separated by at least 1.5 million years and up to 3 million years. We then discuss the impacts of diagenetic deformation on morphology and reevaluate potentially diagnostic characters in light of these new data. For example, the ulna of No. mckinleyi is curved whereas the ulna of No. graffami was considered straight, a character originally separating the two species. However, here we present the difference as much more likely related to diagenetic compression in No. graffami rather than as a true biologic difference. Finally, we include copies of three-dimensional surface scans of all major bones for both taxa for reference.
  • Publication
    Nothronychus mckinleyi Caudal Vertebra
    (2015-01-15) Hedrick, Brandon P
    MSM P2117 caudal vertebra
  • Publication
    Nothronychus graffami Right Humerus
    (2015-01-06) Hedrick, Brandon P
    UMNH VP16420 humerus
  • Publication
    Nothronychus mckinleyi Gastralia
    (2015-01-28) Hedrick, Brandon P
    MSM P2117 gastralia
  • Publication
    Nothronychus mckinleyi Left Ischium
    (2015-01-22) Hedrick, Brandon P
    MSM P2117 left ischium
  • Publication
    Nothronychus mckinleyi Antebrachium
    (2015-01-19) Hedrick, Brandon P
    MSM P2117 antebrachial element
  • Publication
    Nothronychus mckinleyi Left Humerus
    (2015-01-17) Hedrick, Brandon P
    MSM P2117 left humerus
  • Publication
    Nothronychus mckinleyi Left Scapula
    (2015-01-16) Hedrick, Brandon P
    MSM P2117 scapula
  • Publication
    Nothronychus graffami Pubis
    (2015-01-10) Hedrick, Brandon P
    UMNH VP16420 pubis
  • Publication
    Nothronychus graffami Right Scapula
    (2015-01-05) Hedrick, Brandon P
    UMNH VP16420 right scapula