Hedrick, Brandon P

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Now showing 1 - 10 of 41
  • Publication
    Nothronychus graffami Radius
    (2015-01-08) Hedrick, Brandon P
    UMNH VP16420 radius
  • Publication
    Nothronychus graffami Right Fibula
    (2015-01-14) Hedrick, Brandon P
    UMNH VP16420 fibula
  • Publication
    Nothronychus graffami Pubis
    (2015-01-10) Hedrick, Brandon P
    UMNH VP16420 pubis
  • Publication
    Nothronychus mckinleyi Left Humerus
    (2015-01-17) Hedrick, Brandon P
    MSM P2117 left humerus
  • Publication
    Nothronychus mckinleyi Left Ischium
    (2015-01-22) Hedrick, Brandon P
    MSM P2117 left ischium
  • Publication
    Nothronychus mckinleyi Right Humerus
    (2015-01-18) Hedrick, Brandon P
    MSM P2117 right humerus
  • Publication
    Nothronychus mckinleyi Left Scapula
    (2015-01-16) Hedrick, Brandon P
    MSM P2117 scapula
  • Publication
    Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics
    (2013-08-09) Hedrick, Brandon P; Dodson, Peter
    Psittacosaurus is one of the most abundant and speciose genera in the Dinosauria, with fifteen named species. The genus is geographically and temporally widespread with large sample sizes of several of the nominal species allowing detailed analysis of intra- and interspecific variation. We present a reanalysis of three separate, coeval species within the Psittacosauridae; P. lujiatunensis, P. major, and Hongshanosaurus houi from the Lujiatun beds of the Yixian Formation, northeastern China, using three-dimensional geometric morphometrics on a sample set of thirty skulls in combination with a reevaluation of the proposed character states for each species. Using these complementary methods, we show that individual and taphonomic variation are the joint causes of a large range of variation among the skulls when they are plotted in a morphospace. Our results demonstrate that there is only one species of Psittacosaurus within the Lujiatun beds and that the three nominal species represent different taphomorphotypes of P. lujiatunensis. The wide range of geometric morphometric variation in a single species of Psittacosaurus implies that the range of variation found in other dinosaurian groups may also be related to taphonomic distortion rather than interspecific variation. As the morphospace is driven primarily by variation resulting from taphonomic distortion, this study demonstrates that the geometric morphometric approach can only be used with great caution to delineate interspecific variation in Psittacosaurus and likely other dinosaur groups without a complementary evaluation of character states. This study presents the first application of 3D geometric morphometrics to the dinosaurian morphospace and the first attempt to quantify taphonomic variation in dinosaur skulls.
  • Publication
    Nothronychus mckinleyi Manual Phalanx
    (2015-01-21) Hedrick, Brandon P
    MSM P2117 manual phalanx
  • Publication
    Nothronychus graffami Tibia
    (2015-01-13) Hedrick, Brandon P
    UMNH VP16420 tibia