Ecaudate

Ecaudate is a term used in biology, particularly in zoology and paleontology, to describe an animal that lacks a tail. This characteristic can be found in various groups of organisms. For instance, among mammals, humans are a prime example of an ecaudate species, as we do not possess a tail in the way many other primates and mammals do. Some species of amphibians, like certain frogs and toads, are also ecaudate, having lost their tails during metamorphosis.

The absence of a tail can be a result of evolutionary adaptations. In some cases, a tail may have become unnecessary for the animal's lifestyle, such as for arboreal locomotion or balance. Conversely, in other instances, the reduction or loss of a tail can be linked to other developments, like the expansion of the hindquarters or the adoption of a bipedal stance. Fossil evidence can sometimes indicate the presence or absence of tails in extinct species, contributing to our understanding of evolutionary lineages. The term can also be applied more broadly to any organism that lacks a tail-like appendage, regardless of its evolutionary history.