Tremacebus was about in length, and would have resembled a modern
night monkey, to which it is thought to have been related. However, its eyes appear to have been smaller than the modern species. In addition,
CT scans of the
cranium suggest a relatively small
olfactory bulb and poor sense of smell compared with night monkeys. These features suggest that it may not have been nocturnal. It had an estimated body mass of . == References ==