Measuring a Cave Bear's Bite Force Nov 8, 2011 6:34:22 GMT -9
Post by grrraaahhh on Nov 8, 2011 6:34:22 GMT -9
As I stated in the Cranial Bioengineering & Extant Bears thread, measuring a bear's bite force is a complex matter. IMO, this also applies to the Eurasian cave bear. Based on the Thomason (1991) dry skull method, quite a few people are familiar with the following bite force related paper on the cave bear (Ursus spelaeus Rosenmüller):
In this paper, I have made a theoretical calculation of the Cave bear's bite force (BF) following the dry skull method and I present for the first time BF data that can be of interest to elucidate the mechanisms underlying the dietary choice of the Cave bears. In the skulls studied, males show higher BF than females in absolute terms, but more similar with regard to their body mass, which partly compensates for the smaller size of the females. The whole sample studied shows lower BF in the upper carnassial than those of large cats, similar to the one calculated for the Giant panda and higher than that of Polar bear.
Aurora Grandal-d’Anglade (2010). Bite force of the extinct Pleistocene Cave bear Ursus spelaeus Rosenmüller from Europe. Comptes Rendus Palevol, Volume 9, Issue 1, Pages 31-37.
However, another 2010 paper explains the following:
Abstract: The diet of the cave bear group (Ursus spelaeus) has been debated extensively. Traditionally, U. spelaeus was thought to be herbivorous, but more recently studies have shown that it was potentially omnivorous. Presented here is a preliminary study using three-dimensional geometric morphometrics on mandibles of U. spelaeus and its congeners. Multivariate analyses of variance indicate the allometric nature of sexual dimorphism. Principal component analyses and analyses of variance reveal the relationship between morphology and diet in the mandible of extant bears, displaying a gradient from carnivory to herbivory; U. spelaeus is found at the herbivorous extreme, supporting the hypothesis that cave bears were highly herbivorous. The position of the masseteric fossa in U. spelaeus indicates large bite forces necessary for the mastication of tough plant materials. U. americanus has a mandible shape which may reflect previous selection pressures. The necessity of correcting for allometry is shown by comparing the results for corrected and uncorrected data.
"The size and position of the masseteric fossa, which has not been used in geometric morphometric studies of cave bear mandibles until now, has proven to be an important aspect of mandibular functional morphology. The masseteric fossa in cave bears, as compared to modern members of the genus Ursus, is located relatively dorso-posteriorly. This position of the masseteric fossa gives the jaw muscles more power, which may be associated with the consumption of tough plant materials."
Van Heteren, AH, MacLarnon, A, Rae, TC and Soligo, C. (2010) Cave bears and their closest living relatives: a 3D geometric morphometrical approach to the functional morphology of the cave bear Ursus spelaeus. Acta Carsologica Slovaca 47, 33-46.
PDF LINK: www.google.com/url?sa=t&rct=j&q=cave%20bears%20and%20their%20closest%20living%20relatives%3A%20a%203d%20geometric%20morphometrical%20approach%20to%20the%20functional%20morphology%20of%20the%20cave%20bear%20ursus%20spelaeus.&source=web&cd=1&ved=0CBsQFjAA&url=http%3A%2F%2Fwww.ssj.sk%2Fpdf%2FACS_47_S1%2FACS_47_S104.pdf&ei=Qz-5Tv24MaLM2AXO_IDOBw&usg=AFQjCNHs--1EuMrv2KmeujnQRkkdHr0NHA&cad=rja