POSTURAL AND LOCOMOTOR CAPABILITIES IN THE PHENACODONTID CONDYLARTHS (MAMMALIA)

Persistent Link:
http://hdl.handle.net/10150/187554
Title:
POSTURAL AND LOCOMOTOR CAPABILITIES IN THE PHENACODONTID CONDYLARTHS (MAMMALIA)
Author:
Otts, Charlotte
Issue Date:
1991
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The Paleocene and early to middle Eocene Family Phenacodontidae includes three species--Tetraclaenodon puercensis, Phenacodus vortmani, and P. primaevus--with available postcranial material for an investigation of postural and locomotor capabilities. The details of bone and joint morphology are compared within the phenacodontids and with several extant analogues whose postural and locomotor capabilities and morphological correlates are known better. Several aspects of the postcranial morphology of the phenacodontids, especially P. vortmani and P. primaevus, suggest cursorial capabilities. The anterior thoracic vertebral column has limited flexibility dorsoventrally and mediolaterally, but the articular surfaces in the lumbar section, especially in the larger P. primaevus, tend to allow dorsoventral movement while restricting mediolateral movement, thus potentially adding to total stride length. The digitigrade limb posture, again especially developed in P. vortmani and P. primaevus, adds to limb length and stride length. Several features of the joints in the forelimb and hindlimb restrict motion to the parasagittal plane or enhance thrust against the ground in the parasagittal pIane, thus contributing to forward motion. The curvatures of the glenoid fossa and the humeral head enhance flexion and extension and restrict abduction. The mediolateral width and shapes of the articular surfaces in the elbow joint prevent supination. The flexor hinge in the wrist allows a powerful thrust against the ground during push-off. The keels in the distal metapodials maintain that thrust in the parasagittal plane. In the hindlimb, the high greater trochanter and the third trochanter increase the mechanical advantage of some extensors of the femur. The deep patellar groove suggests strong extension at the knee. Similarly, the deep grooves and distinct condyles of the distal tibia and dorsal surface of the astragalus, along with the relatively long calcaneal tuberosity, suggest powerful flexion at the ankle joint and confine motion at the upper ankle joint to flexion and extension. The phenacodontids and especially Phenacodus vortmani and P. primaevus were good runners, particularly compared with their Paleocene and Eocene contemporaries. Within the genus Phenacodus, the more slender P. vortmani, with its more elongate distal elements of the hindlimb, probably was the more efficient runner.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Flessa, Karl W.; Morbeck, M. E.
Committee Chair:
Flessa, Karl W.; Morbeck, M. E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titlePOSTURAL AND LOCOMOTOR CAPABILITIES IN THE PHENACODONTID CONDYLARTHS (MAMMALIA)en_US
dc.creatorOtts, Charlotteen_US
dc.contributor.authorOtts, Charlotteen_US
dc.date.issued1991en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe Paleocene and early to middle Eocene Family Phenacodontidae includes three species--Tetraclaenodon puercensis, Phenacodus vortmani, and P. primaevus--with available postcranial material for an investigation of postural and locomotor capabilities. The details of bone and joint morphology are compared within the phenacodontids and with several extant analogues whose postural and locomotor capabilities and morphological correlates are known better. Several aspects of the postcranial morphology of the phenacodontids, especially P. vortmani and P. primaevus, suggest cursorial capabilities. The anterior thoracic vertebral column has limited flexibility dorsoventrally and mediolaterally, but the articular surfaces in the lumbar section, especially in the larger P. primaevus, tend to allow dorsoventral movement while restricting mediolateral movement, thus potentially adding to total stride length. The digitigrade limb posture, again especially developed in P. vortmani and P. primaevus, adds to limb length and stride length. Several features of the joints in the forelimb and hindlimb restrict motion to the parasagittal plane or enhance thrust against the ground in the parasagittal pIane, thus contributing to forward motion. The curvatures of the glenoid fossa and the humeral head enhance flexion and extension and restrict abduction. The mediolateral width and shapes of the articular surfaces in the elbow joint prevent supination. The flexor hinge in the wrist allows a powerful thrust against the ground during push-off. The keels in the distal metapodials maintain that thrust in the parasagittal plane. In the hindlimb, the high greater trochanter and the third trochanter increase the mechanical advantage of some extensors of the femur. The deep patellar groove suggests strong extension at the knee. Similarly, the deep grooves and distinct condyles of the distal tibia and dorsal surface of the astragalus, along with the relatively long calcaneal tuberosity, suggest powerful flexion at the ankle joint and confine motion at the upper ankle joint to flexion and extension. The phenacodontids and especially Phenacodus vortmani and P. primaevus were good runners, particularly compared with their Paleocene and Eocene contemporaries. Within the genus Phenacodus, the more slender P. vortmani, with its more elongate distal elements of the hindlimb, probably was the more efficient runner.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFlessa, Karl W.en_US
dc.contributor.advisorMorbeck, M. E.en_US
dc.contributor.chairFlessa, Karl W.en_US
dc.contributor.chairMorbeck, M. E.en_US
dc.contributor.committeememberRose, K. D.en_US
dc.contributor.committeememberMartin, P.en_US
dc.contributor.committeememberDevender, T. Vanen_US
dc.contributor.committeememberChaisson, R.en_US
dc.identifier.proquest9123492en_US
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