岩羊和矮岩羊头骨形态特征比较

Comparison of morphological characters of skull between the blue sheep and the dwarf blue sheep

本文报道了岩羊和矮岩羊的头骨形态学资料,涉及头骨特征描述和一些形态学指标测定,被测定的指标主要有上颊齿列基长、眼窝长、乳突间距、眶间距、颧宽、枕颅高、枕髁宽、脑颅最大宽、眶下孔距、上颌臼齿外宽、角基最窄、最小角尖距、角尖距、最大角间距、角基周长、角基长径、角基短径、角外侧长,应用判别分析和单变量分析对岩羊和矮岩羊头骨的测量值进行统计与分析,以探讨这两个种头骨之间的形态差异。结果表明:(1)岩羊和矮岩羊头骨在形态上十分相似,但矮岩羊的头骨细长,脑颅狭窄,角直且朝上翘,角内侧具一明显角棱,亦较直,角基部狭窄,老年个体角基部愈合;岩羊的脑颅宽大,角粗大而长,向两侧分开,弯曲度较大,内侧角棱弯曲呈长S型,角尖朝向后方,角基部较宽,不愈合在一起。(2)岩羊和矮岩羊头骨的18项形态测量指标中乳突间距、眶间距、颧宽、脑颅最大宽、上颌臼齿外宽、角基周长、角基长径差异极显著(P<0.01),枕颅高、枕髁宽、眶下孔距、角尖距、最大角间距、角基短径、角外侧长差异显著(P<0.05);典型判别的正确率:岩羊为100%,矮岩羊为83.3%,交互验证法检验的结果,判别正确率:岩羊100%,矮岩羊为83.3%。这两个判别函数可以从角上区别岩羊和矮岩羊。

The data on skull morphology of the blue sheep and the dwarf blue sheep were reported in this paper. The data involved the measurement and comparison of skull variables between two species. Measured characters include the following： length of the cheek tooth row, greatest inner length of the orbit, greatest mastoid breadth, least breadth between the orbits, zygomatic breadth, least height of the occipital region, greatest breadth of the occipital condyles, greatest neurocranium breadth, foramen infraorbital breadth （ least distance ）, greatest palatal breadth, least breadth between the bases of the horn cores, least distance between the horn core tips, distance between the horn core tips, greatest tangential distance, horn core basal circumference, greastest （ oro-aboral） diameter of the horn core base, least （ dorso-basal ） diameter of the horn core base, and length of the outer curvature of the horn core. Univariate analysis and discriminant analysis were applied to those measurements. The results indicated that： （1） Skulls of the 2 species were very similar in shape, but the dwarf blue sheep was thinner and narrower. The horn straight also faces on curls upwards, the horn base narrower, and the older individuals healing together. Compared with the skull of dwarf blue sheep, that of the blue sheep is more spacious, the horn is thicker and longer, and separates more on both sides, has a longer curvature, the inside horn ridge is longer and shows an S-bend, a sharp angle towards the rear base of a wide angle, not merging. （2） The results of univariate analysis indicated： Of 18 measurements of skull morphology, the differences of greatest mastoid breadth, least breadth between the orbits, zygomatic breadth, greatest neurocranium bread, greatest palatal breadth, horn core basal circumference, greasiest （ oro - aboral ） diameter of the horn core base are extremely significant （ P 〈 0. 0 1 ） ; the differences of least height of the occipital region, greatest breadth of the occipital condyles, foramen infraorbital breadth （least distance）, distance between the horn core tips, greatest tangential distance, and least （ dorso-basal ） diameter of the horn core base are significant （P 〈 0. 05）. The univariate analysis showed the accuracy rate of discrimination for the blue sheep was 100. 0% and for the dwarf blue sheep was 83.3%. Cross validation is done only for those cases in the analysis. In cross validation, each case is classified by the functions derived from all cases other than that case. The accuracy rate for the dwarf blue sheep was 83. 3%, while for the blue sheep was 100%. The two horn distinctions function may distinguish the blue sheep from the dwarf blue sheep.