Anterior premolar variability in Pleistocene cave and brown bears and its significance in species determination
|Klíčová slova||Mammalia, Ursidae, Pleistocene, dentition, premolar pattern, Ursus spelaeus, Ursus arctos|
|Citace||PACHER, Martina. Anterior premolar variability in Pleistocene cave and brown bears and its significance in species determination. Fossil Imprint / Acta Musei Nationalis Pragae, Series B – Historia Naturalis. Prague: National Museum, 2017, 73(3-4), 482-494. DOI: https://doi.org/10.2478/if-2017-0025. ISSN 2533-4050 (tisk), 2533-4069 (online). Also available from: https://publikace.nm.cz/periodicals/fiamnpsbhn/73-3-4/anterior-premolar-variability-in-pleistocene-cave-and-brown-bears-and-its-significance-in-species-determination|
The current study deals with the anterior premolar pattern in the cave and brown bear lineage, and its signiﬁcance in species determination. The occurrence of single premolars and its combinations in skulls and mandibles is recorded for various chronological and regional groups.
Both lineages stay more “conservative” in the upper than in the lower dentition, but show contrasting reduction tendencies. Brown bears tend to retain the ﬁrst premolar, while in the cave bear lineage, third premolars prevail.
Exclusively diagnostic for brown bears is the occurrence of a single P1, as well as a complete dentition in skulls. With caution, the combination of P1 and P3 is characteristic for the Deninger bear/cave bear lineage. This pattern was not observed in the current brown bear sample, but has been mentioned in literature. In mandibles, evidence of a single p1 (and its combinations) and a complete dentition is exclusively found in brown bears.
A single lower p3 is diagnostic for Deninger bears in completely preserved diastema. The absence of all three anterior premolars as typical for the cave bear lineage is occasionally reported for brown bears in literature, but was not observed in the studied material. Other premolar combinations stay scarce in both lineages, and may partly be inﬂuenced by early or pathological tooth loss.
Brown bears reveal no evolutionary trend in premolar reduction. All possible patterns and a similar frequency of complete dentition is found in modern and fossil representatives.
No evidence was found for high variability in the premolar pattern of U. deningeri, as is suggested in literature. The already moderate presence of anterior premolars declines further in Late Pleistocene cave bears. Nonetheless, already the bears of the Cromerian Forest-Bed lack all anterior premolars in mandibles, and hence imply partly evolutionary tendencies in the cave bear lineage, but also populational differences in the occurrence of premolars anterior the P4/p4.