caa a22 4500 445326034 CHVBK 20180317142720.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s10914-010-9145-7 doi (NATIONALLICENCE)springer-10.1007/s10914-010-9145-7 Postcranial Functional Morphology of Hyracotherium (Equidae, Perissodactyla) and Locomotion in the Earliest Horses [Elektronische Daten] [Aaron Wood, Ryan Bebej, Carly Manz, Dana Begun, Philip Gingerich] A nearly complete skeleton of Hyracotherium grangeri is described from the early Wasatchian (early Eocene) of the Clarks Fork Basin in northwestern Wyoming. This specimen includes a virtually complete, well-preserved pre-caudal vertebral column allowing the first thorough investigation of the locomotory abilities of these early Eocene horses. The posterior thorax (T) and lumbus (L) are divided into a facultatively dorsostable region (T15-L3) and an obligately dorsostable region (L3-L7). The facultatively dorsostable region is characterized by robust, cranially-oriented neural spines and well-developed attachment sites for epaxial musculature, whereas the obligately dorsostable region is characterized by embracing zygapophyses and less developed spines and attachment sites. Limb morphology exhibits a mixture of primitive characters and derived features associated with cursoriality. As described by previous authors, limb mobility is restricted at the elbow and ankle due to interlocking humero-radial and tibio-astragalar articulations, respectively. In contrast, the presence of a rounded femoral head and well-developed pelvic and femoral attachment sites for hindlimb adductor muscles suggests a highly mobile hip joint. Limited inversion of the manus and pes may have been possible via differential movement between the proximal and distal carpal elements and at the transverse tarsal joint, respectively. The obligately dorsostable region of the vertebral column likely resisted variably-oriented torque applied by hip musculature, thereby preventing dislocation of the pelvis and lumbus. The facultatively dorsostable region would have facilitated dynamic positioning of the center of mass during rapid acceleration. Brief comparisons with Orohippus and Mesohippus postcrania are used to discuss the selective pressures imposed by changes in body mass and habitat on the postcranial evolution of Paleogene horses. Springer Science+Business Media, LLC, 2010 Hyracotherium nationallicence Postcranial morphology nationallicence Locomotory evolution nationallicence Paleogene equids nationallicence Vertebrae nationallicence Wood Aaron Department of Geological Sciences and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut Bebej Ryan Department of Ecology and Evolutionary Biology and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut Manz Carly Department of Geological Sciences and Florida Museum of Natural History, University of Florida, Gainesville, FL, USA aut Begun Dana Orthopaedic Research Laboratories, Departments of Anthropology and Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA aut Gingerich Philip Department of Geological Sciences and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/1(2011-03-01), 1-32 1064-7554 18:1<1 2011 18 10914 https://doi.org/10.1007/s10914-010-9145-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10914-010-9145-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wood Aaron Department of Geological Sciences and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut NATIONALLICENCE 700 1- Bebej Ryan Department of Ecology and Evolutionary Biology and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut NATIONALLICENCE 700 1- Manz Carly Department of Geological Sciences and Florida Museum of Natural History, University of Florida, Gainesville, FL, USA aut NATIONALLICENCE 700 1- Begun Dana Orthopaedic Research Laboratories, Departments of Anthropology and Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA aut NATIONALLICENCE 700 1- Gingerich Philip Department of Geological Sciences and Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA aut NATIONALLICENCE 773 0- Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/1(2011-03-01), 1-32 1064-7554 18:1<1 2011 18 10914 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer