On newborn calf skulls of Early Pleistocene Mammuthus trogontherii from Shanshenmiaozui in Nihewan Basin, China

Numerous juvenile specimens, including skulls and deciduous teeth of Mammuthus primigenius (Blumenbach, 1799), have been reported, which is rare among the recovered fossil records of the early mammoth species including Mammuthus meridionalis (Nesti, 1825) and Mammuthus trogontherii (Pohlig, 1885). After the publication of the juvenile mandibles and lower deciduous teeth of M. trogontherii, some more specimens, including a nearly complete skull, with the DP2 and DP3 of both sides preserved in situ, have been recovered from the Shanshenmiaozui site for this species. This paper reports the first discovery of the first generation tooth (DP2) for the species M. trogontherii. Both the upper and lower DP2s are more elongated and larger than those of M. primigenius, and the DP3 is also on average larger than that of M. primigenius. The calf skull of M. trogontherii, despite the breakage and deformation, is larger than that of M. primigenius, and it also shows some general characteristics lying between Elephas maximus and Loxodonta africana. The comparative studies in the skull and dental morphology indicate that the differences among the newborn calves of the principal elephantid species, including different mammoth species and the extinct as well as extant Elephas and Loxodonta, are not as obvious as in their adult stages, except that the calf of M. trogontherii is relatively larger.