Discovering an auricular semet in a kangaroo

Macropods ( vary greatly in the colouration of their ear pinnae, from plain ( and and to patterned ( and and

Kangaroos, defined as the five species of macropods with the largest bodies, are generally plain in colouration. However, their ear pinnae have ambivalent patterns.

In this Post, I try for the first time to classify these patterns in terms of the dichotomy between camouflage-colouration on one hand, and small-scale conspicuous colouration for social signalling on the other.

In all kangaroos, the earlashes (see are whitish, and noticeable at close quarters. However, at some distance the species vary between earlashes which could plausibly function as camouflage ( and those which, by virtue of dark emphasis, could plausibly function as an auricular semet (

Along similar lines, the back-of-ear of kangaroos, which is brought partly into view by turning the ears, is plain in certain species but differentiated into dark and pale in others ( and

Of the five species, only the western grey kangaroo (Macropus fuliginosus, combines relatively conspicuous earlashes with a relatively conspicuous back-of-ear. The pattern in this species is certainly conspicuous enough to qualify as an auricular semet: and and and and and

Presumably, the function of an auricular semet in the western grey kangaroo is to facilitate the monitoring of companions in this somewhat gregarious species. However, this raises a question for a future Post: why is it that the closely-related eastern grey kangaroo (Macropus giganteus) has a pattern probably too faint to qualify as an auricular semet?

Macropus giganteus

Macropus fuliginosus

Osphranter robustus

Osphranter antilopinus

Osphranter rufus

Publicado por milewski milewski, 13 de septiembre de 2021


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