 Reference Base  A multivariate comparison of variation in fossil and livi... |
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Bales, G.S., 1993. A multivariate comparison of variation in fossil and living rhinoceros skulls. Journal of Vertebrate Paleontology 13 (Suppl. To no. 3): 24A-25A
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| Location: |
World |
| Subject: |
Taxonomy - Evolution |
| Species: |
All Rhino Species |
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The evolutionary diversity of the superfamily Rhinocerotoidea is represented by relatively many fossils and a few surviving taxa. Morphological variation in the skull was assessed for 15 extinct genera and four extant genera (living analogues). The latter provide a guage of intrageneric and intraspecific variation for the fossils.
Separate multivariate analyses were performed on adult crania (19 measurements on 83 living and 103 fossil specimens) and adult mandibles (11 measurements on 80 living and 84 fossil specimens). These data Included regression estimates of missing values for some specimens.
Procedures programmed in SAS IML, including principal components, were used to observe multivariate within-group dispersions.
The black rhino sample (living genus Diceros) was the best group in terms of sample size (n=48) and homogeneity (monospecific, geographically circumscribed, and no apparent subgroups) and, among the living forms, showed the greatest variation. Variation in fossil genera ranged from greater to less than that of the black rhino. Morphological, geographical, and temporal criteria were used to dissect the fossil genera into subgroups. Morphological variation in these subgroups is generally more consistent with that of the living analogues. Previous species-level designations were not always consistent with the subgroupings.
Mandibles of Aphelops (n=17) provide an example. This genus of Miocene browsers shows a large range of morphological variation divisible Into a temporal sequence of four nonoverlapping subgroups: Barstovian (several localities; includes A. megalodus), late Clarendonian (several localizes), early Hemphillian (several localities; includes A longipes). and late Hemphilian (A. mutilis).
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