title: Astragalar Morphology of Selected Giraffidae.
abstract: The artiodactyl astragalus has been modified to exhibit two trochleae, creating a double pullied structure allowing for significant dorso-plantar motion, and limited mediolateral motion. The astragalus structure is partly influenced by environmental substrates, and correspondingly, morphometric studies can yield paleohabitat information. The present study establishes terminology and describes detailed morphological features on giraffid astragali. Each giraffid astragalus exhibits a unique combination of anatomical characteristics. The giraffid astragalar morphologies reinforce previously established phylogenetic relationships. We find that the enlargement of the navicular head is a feature shared by all giraffids, and that the primitive giraffids possess exceptionally tall astragalar heads in relation to the total astragalar height. The sivatheres and the okapi share a reduced notch on the lateral edge of the astragalus. We find that Samotherium is more primitive in astragalar morphologies than Palaeotragus, which is reinforced by tooth characteristics and ossicone position. Diagnostic anatomical characters on the astragalus allow for giraffid species identifications and a better understanding of Giraffidae.
authors.affiliation: Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, United States of America.|Department of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, United States of America.
authors.forename: Nikos
authors.initials: N
authors.lastname: Solounias
authors.affiliation: Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, United States of America.
authors.forename: Melinda
authors.initials: M
authors.lastname: Danowitz
mesh_terms: D000818:Animals; D005075:Biological Evolution; D000068276:Giraffes / Q000033:anatomy & histology* / Q000145:classification* / Q000502:physiology; D013628:Talus / Q000033:anatomy & histology*