Post by grrraaahhh on Jun 29, 2011 20:39:44 GMT -9
Of the two North American short-faced bear species, Arctodus pristinus is more primitive and could be ancestral to Arctodus simus. The lesser short-faced bear preferred moister, more heavily-wooded eastern coastal regions. Arctodus pristinus lived near the Atlantic coast and in Mexico from Kansan to Wisconsinan (about 800,000 to 10,000 years ago) time. With its relatively longer face, smaller, narrower teeth, and smaller stature, this bear may have been more omnivorous (eating plants as well as animals) than Arctodus simus. Perhaps the lesser short-faced bear died out through competition with a large Pleistocene subspecies of black bear (Ursus americanus amplidens), as well as brown bears invading from the west.
A. pristinus had longer, more slender limb bones than Tremarctos, and its muzzle was similarly short. The anterior premolars were small and well-spaced; the molars were smaller relative to jaw length than in A. simus (Kurten 1967). Height of the jaw articulation was quite variable, from high above the occlusal surface of the cheek teeth to only slightly higher (Emslie, in press). There are too few specimens to identify a representative norm. This variation is difficult to interpret without information on how it compares to variation in other ursids, particularly Tremarctos.
Fossils of A. pristinus have been found only in the southeastern corner of this continent (Fig. and possibly the lower mid-west (Kurten 1967; Kurten & Anderson 1980; Emslie, in press). A. pristinus occupied eastern North America until the Wisconsinan, with the most recent known survivors in Florida where it was sympatric with the spectacled bear, which survived into the Holocene.
Emslie, S.D., 1995, The fossil record of Arctodus pristinus (Ursidae:Tremarctinae) in Florida: Bulletin of the Florida Museum of Natural History, v. 37, p. 501-514.
Harington, C.R. 1973. A short-faced bear from ice age deposits at Lebret, Saskatchewan. Blue Jay 31(1):11-14.
Kurtén, B., 1967, Pleistocene bears of North America. 2. Genus Arctodus, short-faced bears: Acta Zoologica Fennica, v. 117, p. 1-58.
Kurtén, B., & Anderson, E., 1980, Pleistocene mammals of North America: Columbia University Press, New York, 442 p
Stringham, F. S, 1992. Evolution of Bears (manuscript).
A. pristinus had longer, more slender limb bones than Tremarctos, and its muzzle was similarly short. The anterior premolars were small and well-spaced; the molars were smaller relative to jaw length than in A. simus (Kurten 1967). Height of the jaw articulation was quite variable, from high above the occlusal surface of the cheek teeth to only slightly higher (Emslie, in press). There are too few specimens to identify a representative norm. This variation is difficult to interpret without information on how it compares to variation in other ursids, particularly Tremarctos.
Fossils of A. pristinus have been found only in the southeastern corner of this continent (Fig. and possibly the lower mid-west (Kurten 1967; Kurten & Anderson 1980; Emslie, in press). A. pristinus occupied eastern North America until the Wisconsinan, with the most recent known survivors in Florida where it was sympatric with the spectacled bear, which survived into the Holocene.
Emslie, S.D., 1995, The fossil record of Arctodus pristinus (Ursidae:Tremarctinae) in Florida: Bulletin of the Florida Museum of Natural History, v. 37, p. 501-514.
Harington, C.R. 1973. A short-faced bear from ice age deposits at Lebret, Saskatchewan. Blue Jay 31(1):11-14.
Kurtén, B., 1967, Pleistocene bears of North America. 2. Genus Arctodus, short-faced bears: Acta Zoologica Fennica, v. 117, p. 1-58.
Kurtén, B., & Anderson, E., 1980, Pleistocene mammals of North America: Columbia University Press, New York, 442 p
Stringham, F. S, 1992. Evolution of Bears (manuscript).