Evolution by retaining juvenile traits as an adult is known as neoteny.

Other theorists have argued that neoteny has not been the main cause of human evolution, because humans only retain some juvenile traits, while relinquishing others.

It's the retarding of development so juvenile traits are retained in adulthood.

Therefore, the lack of tusks could be a juvenile trait instead of a secondary sexual characteristic, weakening the case for sexual dimorphism.

Valledor de Lozoya has instead suggested that the light plumage was a juvenile trait, a result of bleaching of old taxidermy specimens, or simply artistic license.

This retention of juvenile traits, called neoteny, is a fairly common trait within the genus Eurycea.

In 1998 Dodson and Allison Tumarkin argued that the bone structure could also be explained by species-specific pedomorphosis, the retention by adults of juvenile traits.

Bonaparte (1996) interpreted the relatively large orbital opening in the skull as a juvenile trait.

It has been suggested that this species exhibits pedomorphosis, that is, they retain many juvenile traits into adulthood.

Possible juvenile traits included the lack of a notarium, being a fusion of the front dorsal vertebrae, and a unfused scapula and coracoid.