INVESTIGADORES
ZARATE marcelo Aristides
artículos
Título:
Functional morphology and palaeobiology of the Pliocene rodent Actenomys: the evolution to a subterranean mode of life
Autor/es:
MARIA ELENA FERNÁNDEZ; MARCELO ZÁRATE; ALDO VASSALLO
Revista:
BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: London; Año: 2000 vol. 71 p. 71 - 90
ISSN:
0024-4066
Resumen:
The Pliocene caviomorph rodent Actenomys has long been recognized as an early fossorial representative of the subfamily Ctenomyinae (Octodontidae), which includes one Iiving genus, Ctenomys (tuco-tuco), and several species widely distributed in South America. To assess the degree of specialization for digging in Actenomys, we performed morphological comparisons with other octodontid genera (Octodon, Spalacopus, and Ctenomys) of known mode of life and behavior. As a whole, our results indicate that, in terms of morphological specializations for digging, Actenomys occupies an intermediate positions between Octodon, a generalized semi-fossorial rodent which forages above ground, and Mid Ctenomys-Spalacopsys, two highly specialized subterranean forms. The position of the deltoid process (humeras) and the length of the olecranon process (ulna)—two traits which affect the out forces exerted by several forelimb muscles—were in Actenomys intermediate between non-subterranean and subterranean taxa. The skull, particularly the rostrum, appears to be strong, and sagittal and nuchal crest are well marked. The zygomatyc arches are as flered as those of the generalized Octodon. Notably, the upper and lower incisore of Actenomys were extremaly procumbent, as in many highly specialized chisel-tooth digging species.  Based upon the stratigraphic and sedimentological analysis of the palaeosoils containing its fossil remains, we suggest that Actenomys lived in an environment of moderate to big primary-productivity. The texture of the palaeosoils, indicate that they were hard and highly cohesive.  This situation, which contrasts with that observed in living Clenomyiae, has relevant implications for burrowing cost. The integration of morphological and palaeoenvironmental data allowed testing of hypotheses about the palaecobiological attributes of this ancestral ctenomyine.