Cross‐Sectional Geometry and Scaling in the Baculum of Cuban Hutias (Rodentia: Capromyidae)

Abstract

Bacula from 61 individual hutia (Rodentia) from five species were studied. The purpose was to investigate cross-sectional geometry as an indicator of mechanical behavior in order to answer questions around the origin and maintenance of the mammalian baculum. From images of the apical and basal cross sections, the following variables were calculated: perimeter, cross-sectional area, maximum second moment of area, and polar moment. An allometric analysis showed that these variables were related to body size. The orientation of the maximum second moment of area was analyzed by means of circular statistics. This orientation was transverse in both the apical and basal cross sections. Values for the second moment of area and polar moment, obtained from the predicted value of the allometric equations, showed that either the bending moment or the twisting moment of the baculum must be relatively low in hutias, compared with those of the radius in the same species. The results of the second moment of area predict that the main bending stress acting on the baculum is transverse. At the same time, shear stress would not be negligible. Anat Rec, 303:1346Rec, 303: -1353Rec, 303: , 2020

Capromys pilorides (Rodentia: Echimyidae)

“…The baculum has an elongated mid-shaft with sides more or less parallel, without constriction or subapical stretching at the distal end, it has two small nodules well marked at the basal end. It is dorsoventrally flattened at the mid-shaft, with a convex dorsal area and a ventral concave area (Varona 2012;Casinos et al 2020). Mean baculum measurements (mm; ± SD; parenthetical range) of 57 individuals were: total length, 16.6 ± 2.0 (13.0-21.5); extreme basal width, 3.1 ± 0.4 (2.3-4.3); maximum basal width, 4.1 ± 0.6 (3.1-5.5); extreme apical width, 3.0 ± 0.5 (1.9-4.1); maximum apical width, 3.4 ± 0.6 (2.0-4.8); basal height, 1.3 ± 0.2 (0.9-1.9); apical height, 0.9 ± 0.1 (0.6-1.3-Ramos The esophagus is narrow, the stomach has an oblong shape and the small intestines are about 5 m long (Owen 1832).…”