甘肃临夏盆地晚中新世豪猪一新种

A PORCUPINE FROM LATE MIOCENE OF LINXIA BASIN, GANSU, CHINA

在甘肃临夏盆地发现豪猪化石一新种,甘肃豪猪(Hystrix gansuensis)。其主要特征是:个体大;鼻骨较宽大,后缘圆凸,达M3的后上方;门齿与P4间齿缺长,腭面较宽,两齿列彼此近于平行;后鼻孔前缘弧形;颊齿为中度单面高冠;P4的前边脊短,褶I向颊侧开口,具低小的前附尖;上臼齿褶I不向颊侧开口;M3较少退化。根据共生的哺乳动物群判断,其时代为晚中新世。

In China the living porcupines are known to be distributed in Tibet and the area south to the Yangtze River, not beyond N 35°. The distribution of Quaternary fossil porcupines is known to be much wider than that of today, reaching Benxi in Northeastern China (north to N 41? . However, our knowledge of the Chinese Neogene porcupines is limited to two species from south China: H. zhengi from Pliocene of Sichuan and Guangxi, and Hystrix sp. from late Miocene of Lufeng of Yunnan. So far no fossil porcupines have ever been reported from Gansu Province. The discovery of the new porcupine from Linxia, Gansu, not only widened the distribution of the Neogene porcupines in China,but also shed new light on the evolutionary history of the fossil porcupines.Hystricidae Fischer de Waldheim, 1817Hystrix Linnaeus, 1758 Hystrix gansuensis sp. nov.(Figs. 1,2,4)Holotype Anterior part of skull with left and right P4 - M3 (IVPP V 13052) .Locality and horizon of holotype IVPP Loc, LX 200019, Xiaozacun, Zhuangkeji, Guanghe County, Gansu Province; Late Miocene.Referred specimens Anterior part of skull with left and right dP4 (broken) and M1- 3 (HZM 0401); Rostral part of a skull with a pair of incisors, left P4 and part of M1 (IVPP V 12715-1),a left M3 (IVPP V 12715-2) , and right P4-M2(IVPP V 12715-3), which may belong to the same individual; and a right upper jaw with M1-2 (IVPP V 12716) .Localities and horizons of referred specimens IVPP Loc, LX 200023, Ketuo, Diaotan Xiang, Hezheng County, Gansu Province (HZM 0401), IVPP Loc. LX 200035, Heilingding, Guan-tangou Xiang, Hezheng County, Gansu (V 12715), and IVPP Loc. LX 200014, Shilidun, Chengguan Xiang, Guanghe County, Gansu (V 12716): Late Miocene.Diagnosis Very large sized Hystrix ; nasals enlarged, with convex posterior margin reaching to posterior to M3 , diastem between I and P4 long, palate wide, with two parallel dental series, anterior border of choana concave anteriorly, opposite to between M2 and M3; cheek teeth unilaterally sub-hypsodont, each with three roots; sinus joining only with fold I on dP4; P4 with short anteroloph, large and buccally protruded paracone, tiny and low parastyle and buccally open fold I; upper molars with closed fold I; M3 not much reduced .Description and dimensions(see Chinese text)Comparison The main features of the porcupine from Linxia Basin are almost identical with that of Hystrix , differing from Trichys , Atherurus and Thecurus in being large in size and having enlarged nasals and higher-crowned cheek teeth. It seems to represent a new species of Hystrix , here named as H. gansuensis .H. gansuensis differs from recent and Quaternary species of Hystrix in having lower-crowned cheek teeth. Its cheek teeth are larger than those of H . brachyura , H. subcristata , H . indica , H . javanica , H . lagrelii, H . vinogradovi , H . kiangsenensis , but smaller than those of H . crassidens . In addition, it differs from H . lagrelii, H. sumatrae , H. javanica and H. crassipinis in having an enlarged nasals . It is different from H . magna in having a wider palatine, more anteriorly located anterior margin of choana.The Neogcne species of Hystrix are known include H . panae , H . primigenia , H . sivalensis , H . leakeyi, H . etrusca , H. refossa , H . zhengi, H . depereti ( see Sen, in press, a) , H. aryanensis (see Sen, in press, b) and Hystrix sp. from Lufeng. The crown of the cheek teeth of H. gansuensis are higher than that of H. panae , H . primigenia , H . sivalensis , H . aryanensis and Hystrix sp . , but lower than that of H. leakeyi, H. etrusca , H . refossa and H. zhengi . The cheek teeth of H . gansuensis is larger than those of H. panae and H. leakeyi but slightly smaller than those of H . primigenia in size. Furthermore. H. gansuensis differs from H . primigenia in having two parallel dental series and more anteriorly positioned choana; from H. etrusca in having more posteriorly extending nasals, wider palate and more anteriorly located posterior end of the incisor alveolus. The distinction between H. gansuensis and H. aryanensis is also obviou