Out of Tibet: Pliocene Woolly Rhino Suggests High-Plateau Origin of Ice Age Megaherbivores

Abstract

Ice Age megafauna have long been known to be associated with global cooling during the Pleistocene, and their adaptations to cold environments, such as large body size, long hair, and snow-sweeping structures, are best exemplified by the woolly mammoths and woolly rhinos. These traits were assumed to have evolved as a response to the ice sheet expansion. We report a new Pliocene mammal assemblage from a high-altitude basin in the western Himalayas, including a primitive woolly rhino. These new Tibetan fossils suggest that some megaherbivores first evolved in Tibet before the beginning of the Ice Age. The cold winters in high Tibet served as a habituation ground for the megaherbivores, which became preadapted for the Ice Age, successfully expanding to the Eurasian mammoth steppe.

From ‘third pole’ to north pole: a Himalayan origin for the arctic fox

“…It is thus of interest to speculate that the predominance of predatory canids in the Pliocene of Tibet may also be related to surviving cold winters. The fact that the Tibetan forms predate records elsewhere lends further support for our 'Out-of-Tibet' hypothesis [2], in that, more primitive forms of some mammals evolved first in high Tibet at a time when high arctic regions were much warmer, and subsequently gave rise to Ice Age descendants in northern Eurasia.…”

“…Perhaps not surprisingly, living arctic and Tibetan mammals also share similar adaptations to cold climates, such as long, thick winter fur in arctic muskox and Tibetan yak. Previously, we documented the Tibetan origin of the cold-loving woolly rhinoceros and proposed an 'Out-of-Tibet' hypothesis, in which the Tibetan Plateau served as a cradle of Ice Age megafauna in northern Eurasia [2]. Furthermore, we also documented a deep-time Tibetan origin of a high-altitude Panthera lineage [3], an early precursor of running hyaena Chasmaporthetes [4], as well as a wolf-sized, hypercarnivorous canid [5].…”

“…However with only three specimens in our collection and given the generally poor record of fossil carnivorans, additional collecting is likely to extend the range to younger strata. How much younger this extension will be is not knowable at the moment, but a general scenario seems warranted: an early appearance of a cold-adapted clade that persisted in the high plateau for several million years before descending and spreading northwards, presumably during the Ice Age, as did the woolly rhinoceros [2].…”

Rhinocerotidae from the Upper Miocene deposits of the Western Pannonian Basin (Hungary): implications for migration routes and biogeography

“…However, as noted by Pandolfi (2013) and Pandolfi et al (2015b), D. sumatrensis differs from R. megarhinus in having the posterior border of the nasal notch at the level of P2, the dorsal profile of the skull less concave, the occipital face oblique inclined forward, the external auditory pseudomeatus open, the protocone and the hypocone separated on the upper premolars and the metacone fold well developed on the upper premolars (cranial material of D. sumatrensis housed at MNHN, MSNF, Heissig (1989Heissig ( , 1996Heissig ( , 1999 who suggested an evolutionary lineage leading from Dihoplus schleiermacheri to "Dicerorhinus" megarhinus. Deng et al (2011) ascribed the species R. megarhinus to Dihoplus, but in the parsimonious trees figured by these authors (Deng et al 2011: fig. S7), the genus Dihoplus was paraphyletic and D. megarhinus clearly did not form a clade with the species Dihoplus pikermiensis and Dihoplus ringstroemi.…”

“…S7), the genus Dihoplus was paraphyletic and D. megarhinus clearly did not form a clade with the species Dihoplus pikermiensis and Dihoplus ringstroemi. Moreover, the type species of the genus Dihoplus, D. schleiermacheri, was not included in the analysis of Deng et al (2011). The latter species was considered in the unpublished analysis reported by Pandolfi et al (2014) and Pandolfi (2015a) but it did not form a clade with D. megarhinus which was included within the paraphyletic genus Stephanorhinus Kretzoi 1942.…”