Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Richard D. Andrews


Three criteria, skull size, development of the postorbital process, and cranial suture obliteration were examined to evaluate their effectiveness as possible age indicators in the coyote (Canis latrans). Two collections of coyote skulls were evaluated. The first was 130 skulls of known age, from Utah, which were used to compare the above characteristics to the age of the animal. The second was 151 Illinois Department of Conservation (DOC) skulls of unknown age, which were used in conjunction with the known age skulls to evaluate differences in skull size and observer and inter-observer subjectivity in the classification of suture obliterations.

Cranial measurements revealed male skulls where significantly larger (P < 0.05), than females. Skull sizes differed significantly between the two populations, with Illinois male skulls being larger (P < 0.05), than Utah males in all measurements, and Illinois females being larger (P < 0.05), than Utah females only in mastoid width. Known age females did not differ significantly with age, but three measurements were found significantly different (P < 0.05), in known age males with respect to age.

The postorbital process in the known age coyote skulls revealed some change in shape from rounded to pointed. The rounded condition was only observed in some animals under 6 years of age. Therefore, no specific age estimations could be made from this criterion.

Examination of 19 cranial sutures in the known age skulls revealed only six with age related patterns of closure. Due to the varying degree of closure found in these six sutures, the skulls could only be placed in very broad age classes, rendering the value of suture obliteration unsatisfactory in determining the age of coyotes. The subjectivity encountered in this study was found higher among different workers than between multiple observations by one worker.

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