Master's Theses

Document Type

Thesis - campus only access

Date of Award

Summer 2001

Degree Name

Master of Science (MS)

Department

Geosciences

Advisor

Richard Zawerksi

Abstract

Two coyote species, Canis lepophagus and the modern coyote, Canis latrans are known from the Pliocene and Pleistocene of North America. Canis lepophagus generally is considered a Blancan species, and the oldest specimens that can confidently be allocated to C. latrans are Rancholabrean. Therefore, a significant stratigraphic interval (the Irvingtonian) exists in which fragmentary coyote specimens occur but their species affinities are difficult to evaluate because the variation between C. lepophagus and C. latrans is not adequately known. A relatively large number of coyote specimens recently recovered from the Irvingtonian sediments of Porcupine Cave, Park County, Colorado, are described herein and provided the emphasis to analyze the variation in C. lepophagus and C. latrans. Qualitative and quantitative osteological description of the Porcupine Cave coyotes indicates that they closely resemble recent specimens of C. latrans. The systematic importance of the qualitative variations is difficult to assess because of a general lack of osteological descriptions, especially in the post-cranial skeleton, of fossil and recent small-bodied Canis taxa. Stepwise discriminant analyses were run on a series of 88 measurements taken primarily from specimens of C. lepophagus from Cita Canyon, Texas, and recent coyotes from the three subspecies whose modern ranges include Colorado (C. l. latrans, C. l. lestes, and C. l. mearnsi). The variables and associated data were separated into four anatomical “regions” (cranial, upper dentition, mandibles, and lower dentition) and analyzed independently. The goal was to find what variables of each region contribute the most to interspecific variation so that fragmentary fossil specimens can be analyzed more efficiently and effectively. Canonical discriminant analyses, using the restricted set of variables, then analyzed how well those variables could discriminate the known species. The discriminant functions derived from cranial and mandibular data were able to correctly classify C. latrans and C. lepophagus with 100 percent efficiency, whereas those derived from the dentition were less successful. The measurements exhibiting the greatest variation between C. lepophagus and C. latrans are as follows: postorbital constriction width and braincase height (not including sagittal crest) (cranial); P3 length and P1 width (upper dentition); mandibular condyle depth and mandible width at m2 (mandibular); and m1 width and p3 length (lower dentition). Braincase height was the only variable identified that could provide complete morphologic separation between C. lepophagus and C. latrans. When added as an unknown to the analyses, a relatively complete skull from the Porcupine Cave sample consistently grouped with the modern coyotes, suggesting that Porcupine Cave does contain the oldest-known record of C. latrans.

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© 2001 Gaberiel Bever

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