South American Giant Short-faced Bear's Diet Evolved Through the Pleistocene Quaternary

South American giant short-faced bear (Arctotherium angustidens) diet: evidence from pathology, morphology, stable isotopes, and biomechanics.

Authors:

Soibelzon et al

Abstract:

Arctotherium angustidens Gervais and Ameghino, 1880 (the South American giant short-faced bear) is known for being the earliest (Ensenadan Age, early to middle Pleistocene) and largest (body mass over 1 ton) of five described Arctotherium species endemic to South America. Here we assess the diet of this bear from multiple proxies: morphology, biomechanics, dental pathology, stable isotopes and a previous study using geometric morphometric methodology. Results favor the idea of animal matter consumption, probably from large vertebrates in addition to vegetable matter consumption. Most probably, active hunting was not the unique strategy of this bear for feeding, since its large size and great power may have allowed him to fight for the prey hunted by other Pleistocene carnivores. However, scavenging over mega mammal carcasses was probably another frequent way of feeding. South American short-faced bears adjusted their size and modified their diet through Pleistocene times, probably as a response to the diversification of the carnivore guild (from the few precursory taxa that crossed the Panamanian Isthmus during the Great American Biotic Interchange).

The Social and Sex Lives Of Extinct Miocene Neogene Bear Relative Indarctos arctoides

On the Socio-Sexual Behaviour of the Extinct Ursid Indarctos arctoides: An Approach Based on Its Baculum Size and Morphology

Authors:

1. Juan Abella (a,b)
2. Alberto Valenciano (c,d)
3. Alejandro Pérez-Ramos (d,e)
4. Plinio Montoya (f)
5. Jorge Morales (b)

Affiliations:

a. Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona. Edifici ICP, Campus de la UAB s/n, Barcelona, Spain

b. Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain

c. Departamento de Geología Sedimentaria y Cambio Medioambiental. Instituto de Geociencias (CSIC, UCM), Madrid, Spain

d. Departamento de Paleontología, Facultad de Ciencias Geológicas UCM, Madrid, Spain

e. Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Paterna, Spain

f. Departament de Geologia, Àrea de Paleontologia, Universitat de València, Burjassot, Spain

Abstract:

The fossil bacula, or os penis, constitutes a rare subject of study due to its scarcity in the fossil record. In the present paper we describe five bacula attributed to the bear Indarctos arctoides Depéret, 1895 from the Batallones-3 site (Madrid Basin, Spain). Both the length and morphology of this fossil bacula enabled us to make interpretative approaches to a series of ecological and ethological characters of this bear. Thus, we suggest that I. arctoides could have had prolonged periods of intromission and/or maintenance of intromission during the post-ejaculatory intervals, a multi-male mating system and large home range sizes and/or lower population density. Its size might also have helped females to choose from among the available males.