-
TWO NEW PLEISTOCENE SPECIES OF LEPUS (LEPORIDAE, LAGOMORPHA) FROM CHINA
- ZHANG Zhao—Qun
-
2010, 48(2):
145-160.
-
Asbtract
(
)
PDF (2746KB)
(
)
-
Related Articles |
Metrics
Leporids are a group of widely distributed animals with a long history deep into the Middle Eocene. The earliest leporid fossils so far discovered are Lushilagus described by Li(1965) and Tong et al(1987). The diversity of Leporidae has never been high during its long history. There are only nine extant genera all over the world, and only one genus, Lepus, is living in China. The most abundant fossil materials of Lepus in China were discovered from Zhoukoudian (Choukoutien) localities with well preserved skulls and postcranial bones(Young,1927; Teilhard de Chardin and Pei,1941 etc.). However, identification and systematic study of these fossils have long been hampered by lack of detailed osteological study on the extant species. For a better understanding of the skull characters, the author studied and measured 185 specimens of 8 species of Lepus from China and two specimens of Lepus capensis from South Africa in thecollection of Zoology Institute, Chinese Academy of Sciences. Characters with individual variation and/or age differences include: width of nasal, outline of nasal-frontal suture, size of supraorbital processes, position of the posterior end of incisor foramen, length of the palatinebridge and width of mesopterygoid fossa, development of the squamosal spine, morphology of the upper occipital, and tooth enamel structures etc. Stable characters on adults include: general outline of nasals, lateral depression on the frontal, elevation of the supraorbital processes, depth and width of the temporal fossa, fusion of interparietal with parietal, shape of the anterior groove of upper incisor and cement filling, width of incisive foramen, length of palatine bridge and width of mesopterygoid fossa, morphology of zygomatic, general outline of lower mandible and cheek teeth. Based on the understanding of the skull characters of living species of Lepus and systematic descriptions of the fossils, two new species are erected in this paper,i.e. Lepus teilhardi sp. nov. from CKT(Zhoukoudian) Loc.13 and Lepus ziboensis sp. nov. from Zibo, Shandong Province. One well preserved skull(RV 41023) from CKT Loc.13 described by Teilhard de Chardin and Pei(1941) as Lepus wongi is here selected as the type specimen of Lepus teilhardi sp. nov. Lepus teilhardi sp. nov. is characterized by having large size with skull length longer than 90mm, slightly elevated supraorbital processes with short anterior branch and developed posteriorbranch, shallow lateral depressions on the frontals, medium size of masseteric process, deep masseteric fossa on the zygomatic, width of mesopterygoid fossa obviously larger than the minimum length of palatine bridge, narrow and long incisive foramen, large tympanic bullae, wide ectoccipital,V shaped anterior groove on I2 with some cement filling, and posteriorly inclined coronoid process. Lepus teilhardi differs from L. hainanicus in having a V shaped anterior groove on I2 and less cement filling, gradually narrowing of nasals anteriorly, and much shorter palatine bridge, longer diastema on lower jaw etc.L. comus has a narrow and deep anterior groove on I2, the interparietal not fully fused with parietal and slender lower jaws.L. oiostolus can be distinguished from the new species by having well developed and elevated supraorbital processes, anteriorly extended inner side of the anterior groove on I2, deep lateral depressions on the frontals.L.mandschuricus is smaller, has a wider and shallower anterior groove on I2 without cement fillings, unelevated supraorbital processes and well developed masseteric processes. Though L.timidus is comparable with L. teilhardi in size, it can be distinguished from the latter by having a square shaped cross section of I2 with extremely shallow anterior groove and no cement, wider nasals and more developed supraorbital processes, wider mesopterygoid fossa, and upright coronoid process.L. yarkandensis is smaller in size, has much larger tympanic bullae, shorter distance between the bullae and narrow basioccipital. The ratio of width of mesopterygoid fossa and length of palatine bridge of Lepus teilhardi is comparable with L. sinensis. However, it is larger in size, has wider ventral surface of masseteric processes, deep masseteric fossae, and well developed supraorbitals. Compared with the living L. europaeus,L. teilhardi is smaller with longer palatine bridge and narrower mesopterygoid fossa. Although there is no distinct morphological character to separate with living L. capensis, Lepus teilhardi is larger in size with flatter parietals, and shorter palatine bridge. The Simpson index of 13 morphometric characters also shows obvious difference with larger value. Measurements and statistical analyses can easily separate Lepus teilhardi with Lepus sp. from CKT Loc.20. Fossils described as Lepus wongi from Chenjiawo Homo locality are here assigned to Lepus teilhardi. Fossils from Loc.2 of Sunjiashan Hill, Zibo, Shandong Province are here named as Lepus ziboensis sp. nov. It is characterized by having a narrow and shallow anterior groove on I2 filling with cement, slender rostrum, long palatine bridge, relatively narrow mesopterygoid fossa, and shallow reentrants on P2. Biochronologic analysis shows its late Early Pleistocene age. Lepus ziboensis is by far the earliest record of Lepus from China.
