The muzzle-ring as a deep ancestral marker in deer, part 1

Deer are divided into two subfamilies: cervine deer, originating in Eurasia, and odocoileine deer, which have undergone an evolutionary radiation in the Americas (see

Widespread among deer is a pattern of colouration on the facial fur, which I call the muzzle-ring.

The dark next to the bare skin of the nose (rhinarium) extends down to the sides of the lips. Separating this dark from the rest of the face is a vague pale band. The combination of dark and pale bands defines the muzzle-ring.

I show many photos below but the following of the white-tailed deer (Odocoileus virginianus) is a particularly clear illustration: .

The muzzle-ring can be seen, at least vestigially, in both subfamilies of deer. This indicates that it was already present in the last common ancestor, which lived as long as 15 million years ago (see

However, the subfamilies differ.

In odocoileine deer the muzzle-ring is common, occurring in females and males alike, and in most of the genera. By contrast, in cervine deer the muzzle-ring occurs mainly in males, and in a minor proportion of genera: e.g. Axis ( and, Elaphurus (, Dama ( and Cervus (Cervus elaphus: and and

I have mentioned in previous Posts that the odocoileine genus Mazama is odd in combining a primitive appearance with advanced genetic complexity. This is one of the few genera in its subfamily in which the muzzle-ring is absent, making Mazama even more puzzling.

The rest of this post is devoted to illustrating the muzzle-ring in the various odocoileine deer. At least a faint vestige of it occurs in most odocoileine genera. In those species with seasonal changes in colouration, the muzzle-ring tends to be clearest in the winter coat. To keep the comparisons as simple as possible I have chosen photos of only females.

In Alces alces, there is a faint trace of the muzzle-ring despite the plainness of the colouration and the extreme modification of the muzzle: and and and

In the white-tailed deer (Odocoileus virginianus), the following show the muzzle-ring in frontal and profile views: and and and and and and

Although those subspecies of O. virginianus occurring in tropical forest look more like Mazama than the typical white-tailed deer, the muzzle-ring is retained:
see sixth photo in and eight photo in

In Odocoileus hemionus hemionus, the muzzle-ring is fainter than in O. virginianus: and and

In Rangifer tarandus, the muzzle-ring is absent because only the dark component is present:

In Capreolus capreolus, the muzzle-ring is present despite the small size of the muzzle: and and

In Blastocerus dichotomus, the muzzle-ring is present: and

In Ozotoceros bezoarticus, the muzzle-ring is faintly present in at least some individuals: and

In Hippocamelus bisulcus, the muzzle-ring is present: and and

I have yet to find any photos of Mazama showing even a faint version of the muzzle-ring. The closest is the following of Mazama gouazoubira: The following is labelled Mazama but I suspect it to be a tropical form of Odocoileus virginianus:

In Pudu puda, there is a faint vestige of the muzzle-ring: and and

פורסם על-ידי milewski milewski, אוגוסט 28, 2021 02:56 לפנה"צ


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