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REVISION OF CHINESE PLEISTOCENE LEPUS (LEPORIDAE, LAGOMORPHA)
- ZHANG Zhao-Qun
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2010, 48(3):
262-274.
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Taxonomy of Lepus at species level has long been disputed, and the argument is still ongoing. Living hares from North China have respectively been assigned to Lepus tolai,L. oiostolus, L. capensis,L. europaeus during the long history of study. More confusingly, recent molecular analysis favored their close affinity with Lepus timidus (Wu et al.,2005). The discrepancy obviously has direct impact on the study of fossil hares.A large quantity of Pleistocene fossils discovered from Zhoukoudian(Choukoutien) were respectively named after the recent hares except a new species, Lepus wongi erected by Young in 1927. Teilhard de Chardin and Pei(1941) went even further and conventionally included all fossil hares of the Early Pleistocene(Zhou-koudianian stage, now the Middle Pleistocene) in L. wongi, considering of the difficulties of comparison with living hares. This concept was later widely cited. Based on the understanding of osteological characters and morphometric measurements of extant species of Lepus from China, the present author(2010) erected a new species,L. teil-hardi, for the abundant materials from CKT Loc.13, and L. ziboensis for fossils from Zibo, Shandong Province. This paper gives an updated revision for the fossil specimens of Lepus housed in IVPP that have not yet been described or revised from various Pleistocene localities (mainly Zhoukoudian). Observation on the two skulls of Lepus capensis from South Africa housed in Institute of Zoology, Chinese Academy of Sciences, leads the present author to follow Ma et al.(1987) and Luo(1988) using L. capensis for hares from North China. Among the CKT localities, Loc.20 is one of the most productive sites with 33 skulls and 117 lower jaws named by Jia et al.(1959) as Lepus sp., however, with no description. Same as the living Lepus capensis, these materials show V shaped anterior groove on I2 with cement filling, developed supraorbital processes, low squamosal spine, wide and flat parietal, incisiveforamen enlarged from the posterior part, narrow zygomatic arch, small masseteric process sur-face, and posteriorly inclined coronoid process on lower jaws. Morphometric data of the skulls and lower jaws show great similarity with living L. capensis from North China with slightly shorter diastema and longer upper tooth row(Fig.1). Both the morphologic characters and measurements support their conspecific status with L. capensis. Reexamination of the type specimen of Lepus wongi housed in the Museum of Evolution, Uppsala University and a specimen from the same locality(CKT Loc.2) in IVPP confirms the similarity with living L. capensis from North China and fossils from CKT Loc.20 with minor differences. Their morphometric data fall within the range of L. capensis from Loc.20. Hence, the specimens from Loc.2 should be assigned into L. capensis, and L. wongi is therefore not a valid name. According to Pei(1940), the CKT Upper Cave produced thousands of specimens which were named as Lepus europaeus following Allen(1938). Unfortunately, there found only 8 skulls,72 lower jaws and 8 broken pelvis in the IVPP collection. The morphometric data fit well with the living L. capensis(Fig.1) with slightly larger size. No complete skull was found from CKT Loc.1. The only preserved broken skull has short diastema, comparable with young individuals from Loc.20. The small sized lower jaws named as Lepus sp.A and Lepus sp.B have slender incisors, less worn and slightly upward constriction check teeth, nutrition foramina at the diastema part not developed. These characters are typical for young individuals, and comparable with those of the same age of Lepus capensis. There is no detailed description and report on CKT Loc.16. Orally informed by Jia Lanpo, this locality is not far from CKT Loc.18. Fossils include 2 broken skulls and many postcranials. They are tentatively referred to Lepus sinensis,a species nowadays habiting in South China. In total, there are at least three species found from Zhoukoudian localities,e.g. Lepus teilhardi from Loc.13,I. sinensis from Loc.16, and L. capensis from Loc.1,2,20, and the Upper Cave etc. Specimens from CKT Loc.9 are close to L.ziboensis with uncertainty. The other two species of Lepus are L. mandschuricus from the Middle Pleistocene Jinniushan site, Liaoning Province, and L. comus from the Late Pleistocene Sanjiadian locality, Yunnan Province. The earliest record of Lepus found from China so far should be L. ziboensis, of late Early Pleistocene. Till now there have been proposed four candidate ancestors of Lepus, Hypolagus, Alilepus, Nekrolagus, and Trischizolagus. The Hpolagus origin hypothesis is no longer followed for its distinct differences with Lepus. Dawson(1958) and Repenning (1967) considered that Alilepus has similar skull morphology with Lepus. However there has no transition form of p3 between them, especially lacking the anterior reentrant on all available p3s."Caprolagus"brachypus from Early Pleistocene localities (renamed as Sericolagus brachypus by Averianov 1996) was considered to be intermediate between Alilepus and Lepus by Qiu and Han (1986). Its primitive characters of lower mandibles do not favor the possibility. The presence of Lepus pattern p3 on Nekrolagus was dated back to Hemphilian of Florida, North America. Whether Nekrolagus gave rise to Lepus or Sylvilagus is waiting for more data. Averianov(1995) proposed Trischizolagus dumitrescuae as the direct ancestor of Lepus. Undescribed materials of cf. Trischizolagus dumitrescuae from Lingtai, Gansu Province support the close relationship between Trischizolagus and lepus. However, the strong folds on the hypstriae of P4-M2 and external reentrants on p4-m2 of T. dumitrescuae disprove the direct relationship. The earliest record of Lepus pattern p3 in China was found from the Middle Pliocene of Yushe basin(MN15 equivalent), coexisting with cf. Trischizolagus dumitrescuae(Wu Wenyu, unpublished data). Hence, the ancestor of Lepus might be from Early Pliocene, waiting for the future discovery.
