The Tasmanian tiger (Thylacinus cynocephalus) (thylacine) is the basal lineage of the Dasyuromorphia order. The last known specimen died in the Beaumaris Zoo, Hobart, in 1938. Two of its close relatives are the Tasmanian devil (Sarcophilius harrisii) and numbat (Myrmecobius fasciatus), both of which are considered endangered. By a fortunate sequence of events, thylacine hairs were made available for examination and electron microscopy has been used to compare the internal and external morphology of the hairs to the other two species.
Mammalian hair consists of a central cortex (sometimes with a central medullated core with air gaps and shrunken cells) surrounded by a layer or layers of overlapping cuticle cells. Most mammals have two types of body hair, guard and fur hairs, whereas the thylacine has been found to have three types: over hair, guard hair and under (or fur) hair1. There are three types of cuticle patterns: coronal (small rodents and bats), imbricate (most mammals) and spinous2 (mainly in minks and cats).
In this work both SEM and TEM were used to examine the hairs. Findings included the facts that the three types of thylacine hair had an imbricate cuticle structure and were medullated. There were differences in diameter and cuticle frequency and thickness between the three hair types. Similarly, both types of Tasmanian devil hairs had the imbricate cuticle structure and differences in diameter, cuticle frequency and thickness between the guard and fur hairs. In the case of the numbat, the guard hairs had an imbricate structure, but the fur hairs were spinous.
Though the thylacine is extinct, the characterisation of the hairs will enable researchers to determine if nests found in many areas of Tasmania were in fact used by thylacines and hence add to our knowledge of the regions and habitats it used to occupy.