Observations on the anatomy of the tail in the vervet monkey, cercopithecus, which bear on thermoregulatory function in the organ (Primata: Cercopithecidae)

Abstract

A long tail is characteristic of the Family Cercopithecidae but apart from a limited contribution to postural adjustment no other function seems obvious.

The tail has a large proportion of skin which contributes significantly to the total body surface area. Because it has a widely adjustable blood flow rate and appears specially adapted for low flow rates under cool conditions a thermoregulatory function is ascribed to it.

The structural arrangement of the blood vessels favours heat loss mechanisms but this may be disadvantageous under cold conditions. A system of venae comitantes affecting the upper portion of the arterial supply, which could function as a counter-current heat trap, is described.

The origin of the caudal nerves and the continuation of the sympathetic chain into the fourth postsacral vertebral segment is described.