Use of epiphyseal and total fusion scores as methods of age estimation and evaluation of morphological indices in the macropodidae
Ballard, Caroline K.
MetadataShow full item record
This dissertation developed and assessed postcranial age estimation methods in the Macropodidae. Data was collected from museum specimens of nine macropodid genera. Collected data included both postcranial measurements of size, shape, and epiphysial fusion and cheek tooth observations of morphology and eruption. The objectives of this study were: 1) to describe cheek tooth morphology for species absent in the literature, 2) develop a system for scoring molar eruption, 3) describe molar eruption patterns across the family, 4) develop a method for estimating age using degree of fusion at the epiphysis of the forelimb, 5) describe patterns of epiphyseal fusion in the forelimb across the family, 6) use epiphyseal fusion scores to assign specimens to age categories, 7) assess whether any specimens with partly unfused epiphyses can be placed in the same morphological group as those with totally fused epiphyses, and 8) to compare potential postcranial age estimation methods. The results of this study show that of the four postcranial age estimation methods (total fusion, humerus fusion, ulna fusion, and radius fusion), that of humerus epiphyseal fusion is the most significant when regressed on and correlated with molar eruption scores and as such is the best indicator of age. The other three postcranial fusion scores also are significant (though less so) when regressed on and correlated with molar eruption scores and can therefore also be used in age estimation. Results for age categories and assessing which specimens group together morphologically were less clear. Discriminant function analysis using the long bones did clearly show three age categories: adult (fusion scores of 5), subadult (fusion scores of 3 and 4), and juvenile (fusion scores of 1 and 2). However, these analyses also showed that on some of the functions generated by the analyses (especially those where measures of the trochlea and capitulum were influential) the highest three scores were indistinguishable, indicating that these specimens grouped together and could be included in the same morphological study. Discriminant function analysis using total fusion scores did not produce meaningful plots.