Date Published: February 12, 2019
Publisher: Public Library of Science
Author(s): Sukuan Hou, Michael Cydylo, Melinda Danowitz, Nikos Solounias, Suzannah Rutherford.
We are describing and figuring for the first time skulls of Schansitherium tafeli, which are abundant in the Gansu area of China from the Late Miocene. They were animals about the size of Samotherium with shorter necks that had two pairs of ossicones that merge at the base, which is unlike Samotherium. The anterior ossicones consist of anterior lineations, which may represent growth lines. They were likely mixed feeders similar to Samotherium. Schansitherium is tentatively placed in a very close position to Samotherium. Samotherium and Schansitherium represent a pair of morphologically very similar species that likely coexisted similarly to pairs of modern species, where the main difference is in the ossicones. Pairs of ruminants in Africa, for example, exist today that differ mostly in their horn shape but otherwise are similar in size, shape, and diet. The absence of Schansitherium from Europe is interesting, however, as Samotherium is found in both locations. While is it challenging to interpret neck length and ossicone shape in terms of function in combat, we offer our hypothesis as to how the two species differed in their fighting techniques.
Giraffidae are Pecora ruminants . There are approximately twenty-five species of Giraffidae, two extant and the rest are extinct [2–3]. The modern giraffe possesses exceptionally elongated cervical vertebrae and metapodials; the extinct taxa exhibit varying degrees of neck and limb elongation [4–6]. Giraffidae possess specialized cranial appendages termed ossicones, which start as separate ossifications that subsequently fuse to the skull [2, 7–9]. Among the Giraffidae, several taxa exhibit atypical ossicone structure, including the sivatheres Sivatherium and Bramatherium and the samothere Schansitherium. The first two have been reported and figured [10–12]. Unlike these, Schansitherium is poorly described and studied.
We studied Schansitherium and Samotherium material in Beijing IVPP and Hezheng HPM. We also studied in person the Samotherium material in AMNH, NHMUK, and other museums. We describe the skull, third cervical vertebra, metacarpal and metatarsal of Schansitherium tafeli from Gansu and of Samotherium boissieri from AMNH, NHMUK, and Gansu. The material from AMNH and NHMUK were previously studied by Kostopoulos , Hamilton , and Bohlin . The material from Gansu are described for the first time in this paper. The Samotherium boissieri skull used for the comparisons is of great value as it is complete and not crushed. This skull enables us to study the details of the ossicone and its apex, the occipital and the basicranium. We compare the cranial and post-cranial material of these two taxa. We use cervical vertebral terminology and characteristics established by Danowitz and Solounias  and Danowitz et al. . We use metapodial terminology established by Rios et al. .
Type species: Samotherium boissieri Major, 1888