A possible function for an enigmatic synapomorphy of Didelphis

GIANNINI, N; GAUDIOSO, P; FLORES, D.; GAUDIN, T.

ZEITSCHRIFT FUR SAUGETIERKUNDE-INTERNATIONAL JOURNAL OF MAMMALIAN BIOLOGY

Elsevier

Año: 2011 vol. 76 p. 512 - 514

0044-3468

A conspicuous synapomorphy of the marsupial genus Didelphis is the hypertrophied spinous process of cervical vertebrae (C). The tall, thick spinous processes of C2 to C6 interlock preventing any movement of the neck. A functional interpretation of this structure has been elusive. On the basis of osteological specimens of D. albiventris and D. virginiana, we propose a possible function. These specimens show large, partially healed wounds in the spinous processes, indicating that the specimens survived major traumatisms probably caused by carnivorans, so that the spinous processes may have acted as neck armor. Didelphis exhibits several other, well-known defensive traits which, in combination with generalized feeding and locomotor habits, altogether may have helped the lineage survive the Late Tertiary extinction waves in South America and the Great American Biotic Interchange.