Individual Skull Research Articles

Multivariate Analyses of Skull Morphometrics from the Two Species of Grey Kangaroos, Macropus giganteus Shaw and M. fuliginosus (Desmarest)

Species of grey kangaroos may be distinguished on the basis of differences in coat colour. Although alleviating the need for special equipment the technique lacks accuracy. It was hoped that possible morphological differences reflected in skull size and shape might discriminate between species. Thirty parameters were measured from each of 148 reference skulls and differences between species, sexes, and interaction between species and sexes, were tested by univariate analysis of variance. Canonical variate analysis was then used to discriminate by species and sex between eastern greys and mainland and insular forms of the western grey kangaroo. The discriminants derived from these reference skulls were then used to allocate by species and sex a further set of 52 skulls, drawn from small samples and a variety of localities. This allocation was less successful. The validity of the technique is discussed in relation to the analysis of large samples from a restricted locality, as opposed to small samples or individual skulls.

Intraspecific Variation in the Cranial Feeding Mechanism of Turtles of the Genus Trionyx (Reptilia, Testudines, Trionychidae)

and time. Variation in the jaws of T. ferox is shown to be co-existent with variation in 1) other skull features which are presumed to be part of the cranial feeding mechanism, 2) the rhamphotheca or beak, 3) jaw musculature, and 4) feeding habits. In T. ferox, females attain larger size and show more extreme variation in cranial form and diet than males; however the allometric trends are common to both sexes. The relative development of the different features of the cranial feeding mechanism does not reflect a highly integrated structural system. There is no evidence of sexual dimorphism (sensu stricto) nor is there a high correlation between individual skull form and specific food, items. Such a loosely correlated system indicates low selection pressures regarding trophic specialization; individual homeostasis would appear to be a sufficient adaptive strategy.

Dall Sheep Demography in McKinley Park and a Reevaluation of Murie's Data

Dall Sheep Demography in McKinley Park and a Reevaluation of Murie's Data

Taxonomic Status of the Pleistocene Badger, Taxidea marylandica

holotype of Taxidea marylandica, a Pleistocene fossil badger from Cumberland Cave, Maryland, has been listed twice by Gidley and Gazin as a distinct species. This fossil has also been placed by Hall and by Hall and Kelson in the of a Recent subspecies of badger, Taxidea taxus taxus. On the basis of examination of many North American Recent badgers and of the holotype of T. marylandica, I conclude that the fossil badger is definitely referable to the Recent species of Taxidea taxus and is, in fact, referable to a well- differentiated, northern infraspecific kind. fossil possesses one unique character, a straight-sided, subquadrangular upper molar. In addition, the fossil possesses several characters rarely seen in Recent badgers. In consideration of these characters, which may be assumed to have occurred with higher frequency in T. marylandica than in Recent badgers, the fossil may be recognized as representative of a subspecies. of badger (genus Taxidea) on the basis of a well-preserved fossil skull, an articulated series of 11 vertebrae, and the proximal half of the right humerus, all of which were obtained from Pleistocene deposits of Cumberland Cave, Maryland. skull was said to resemble in ap- pearance skulls of individuals of the Recent badger, Taxidea taxus, but several characters of the skull were considered by Gidley and Gazin as distinctive and significant enough for specific recognition of the fossil skull. Therefore, the name Taxidea marylandica was applied to it. Hall (1936:78) regarded the skull as representative of the Recent species Taxidea taxus and listed the fossil skull as worthv of comparison with the Recent subspecies Taxidea taxus taxus Hall stated that the morphological characters considered diagnostic by Gid- ley and Gazin could be found in certain Recent specimens of T. taxus, with the exception of two. dorsal outline of the occiput of the fossil holotype in lateral view was not matched exactly in Recent speci- mens, but some specimens were observed with occiputs higher and lower than in the holotype, that is, showing more or less depression than that of the holotype. In Recent specimens, nasals with nearly parallel lateral margins (constricted abruptly posteriorly in dorsal view) also were found by Hall to not agree precisely with the holotype. He observed Nevadan specimens having nasals similar to those of the holo- type, differing in size but not in proportions. Hall placed the name marylandica in the synonymy of Taxidea taxus taxus (Schreber). In a later publication, Gazin (in Gidley and Gazin, 1938:47-49) again regarded the fossil as representative of a distinct species, stating The junior author does not regard this specimen as sufficiently typical of Taxidea taxus taxus to be placed in the modern species and sub- species, as does Hall (1936:79-82). Hall and Kelson (1959:928) replaced the name marylandica in the of Taxidea taxus

COMPARISON OF THE BLOCK ISLAND “SPECIES” OF MICROTUS WITH M. PENNSYLVANICUS

Block Island is a small continental island, about 11 square miles in area, located approximately 15 miles northeast of Montauk Point, L. I., N. Y., and southwest by south of Point Judith, R. I. (see figure 1). Several years ago it was suggested that the Microtus inhabiting the island were sufficiently different morphologically from the field mice on the neighboring mainland (Microtus pennsylvanicus) to warrant species status for the island mice (Microtus provectus) (Bangs, 1908). Recent work has shown that the two populations are not sexually isolated to a degree which prevents the production of F1 hybrids (Wheeler, 1952) and in view of these findings, it seemed essential to reexamine Microtus from both localities not only to confirm and more thoroughly analyze the differences already indicated by Bangs (1908) but to determine whether other differences do exist which would indicate genetic divergence to any degree. The insular species, Microtus provectus, has been described, first of all, as somewhat larger than the mainland Microtus. In view of this, the present investigation includes a statistical analysis of the body size of mice from both insular and mainland populations in addition to a comparison of body lengths of mature specimens within each population. Since other size differences associated with the skull were also suggested (Bangs, 1908), the experimental data in this paper include size comparisons of some of the individual skull bones and comparisons of various measurements made on the skulls as a whole. MATERIAL AND METHODS

Contour Diagrams of Human Crania

IN the last number of Biometrika (viii., 1, 2, 1911) Prof. Karl Pearson has edited and published a very valuable paper by the late Dr. Crewdson Benington on cranial type-contours. The work is based on long series of skulls of various races, e.g. English of the seventeenth century (from the Whitechapel Plague Pit), modern English (Royal Engineers), various Negro races from the Congo, Guanche, Egyptian, Eskimo, and the prehistoric Cro-magnon skull. For each series three typical contours are selected, viz.:—(1) a “transverse vertical”, passing through the auricular points and the apex of the skull; (2) a sagittal or median section; and (3) a horizontal section through the glabella; and in each case all the individual skulls of a series are combined into a single “type” by a process of arithmetic averages. Lastly, the diagrams thus obtained are reproduced on tissue-paper, so that one may be superposed upon another, and the characteristic differences easily compared.