The muzzle-ring as a deep ancestral marker in deer (Cervidae), part 2: the gape-spot

...continued from https://www.inaturalist.org/posts/55779-the-muzzle-ring-as-a-deep-ancestral-marker-in-deer-part-1#

The muzzle-ring, described in part 1, extends on to the lower jaw in the form of a dark marking near the corner of the mouth (e.g. Rucervus eldi https://www.gettyimages.com.au/detail/video/close-up-brow-antlered-deer-is-chewing-the-food-stock-footage/186723543?adppopup=true and Cervus elaphus https://www.inaturalist.org/observations/64242548).

Because this is the only part of the muzzle-ring that remains in many species of deer (particularly in females of cervine deer), it deserves a name in its own right: the gape-spot.

What emerges is the following generalisation.

No feature of colouration in deer (Cervidae) rivals the gape-spot in its consistent presence - albeit in many cases as only a faint trace - across subfamilies, genera, species, sexes, ages and individuals. At the same time, the gape-spot is consistently absent from bovids (Bovidae).

Although several species of deer (e.g. Muntiacus reevesi) lack the gape-spot, this feature can be seen in most genera and is virtually diagnostic of the family Cervidae as opposed to Bovidae.

This means that the gape-spot seems to be one of the deepest ancestral markers to be found in the colouration of ruminants.

Where the gape-spot is well-developed, it possibly forms part of buccal semets (https://www.inaturalist.org/journal/milewski/100574-a-new-feature-of-adaptive-colouration-in-the-grey-rhebok-pelea-capreolus-the-buccal-semet#). However, in many species of deer it is so faint, so small, and so individually variable that it seems to be vestigial.

Again, I have tried to standardise the illustrations below by choosing females as far as possible. However, in some cases I have included males because, in general, the gape-spot seems to be somewhat better-developed in males than in females.

ODOCOILEINES

Alces alces https://www.gettyimages.com.au/detail/photo/moose-royalty-free-image/1300333648?adppopup=true and https://www.gettyimages.com.au/detail/photo/norway-bardu-profile-of-an-elk-in-winter-royalty-free-image/548309669?adppopup=true and https://carolondenman.files.wordpress.com/2015/01/p1190242.jpg and https://www.gettyimages.com.au/detail/photo/young-elk-with-head-up-royalty-free-image/1287044771?adppopup=true

Rangifer tarandus https://www.gettyimages.com.au/detail/video/reindeer-close-up-sweden-stock-footage/jft03470 and https://www.shutterstock.com/nb/video/clip-1026346898-close-slowmotion-reindeer-eating-while-watching-camera

Capreolus capreolus https://www.alamy.com/ree-close-up-roe-deer-close-up-image211577197.html and https://www.shutterstock.com/nb/image-photo/european-roe-deer-capreolus-3-years-104241920 and https://www.shutterstock.com/nb/image-photo/european-roe-deer-capreolus-3-years-104241935

Hydropotes inermis https://www.wildlifetrusts.org/wildlife-explorer/mammals/chinese-water-deer and https://www.animalspot.net/wp-content/uploads/2018/08/Chinese-Water-Deer-Female.jpg and https://www.alamy.com/chinese-water-deer-hydropotes-inermis-female-image61782239.html and https://www.istockphoto.com/photo/chinese-water-deer-gm1148247620-310039642

Odocoileus virginianus https://www.alamy.com/stock-photo-close-up-head-of-whitetail-doe-side-view-102118313.html and https://www.gettyimages.com.au/detail/photo/profile-of-deer-royalty-free-image/150323281?adppopup=true

https://www.alamy.com/stock-photo-central-american-red-brocket-deer-manuel-antonio-central-pacific-costa-11715472.html

Odocoileus hemionus hemionus https://www.pond5.com/stock-footage/item/89341508-female-mule-deer-face-big-ears-close

Odocoileus hemionus columbianus https://www.shutterstock.com/image-photo/side-profile-female-black-tailed-deer-717758929

Blastocerus dichotomus https://animalia.bio/marsh-deer and https://www.dreamstime.com/female-marsh-deer-blastocerus-dichotomus-female-marsh-deer-blastocerus-dichotomus-eating-grass-image112445694 and https://www.dreamstime.com/female-marsh-deer-blastocerus-dichotomus-closeup-looking-camera-image112445774

Ozotoceros bezoarticus https://www.dreamstime.com/stock-images-pampas-deer-eating-grass-image10037244 and https://commons.wikimedia.org/wiki/File:Pampas_deer_doe_Pousada_Embiara.jpg and male: https://www.sciencephoto.com/media/493604/view/pampas-deer-in-a-meadow

Hippocamelus bisulcus https://www.istockphoto.com/photo/guemal-hippocamelus-bisulcus-in-deep-snow-on-a-mountain-side-in-winter-in-torres-del-gm947670896-258749642 and https://business.facebook.com/fundacionrewildingchile/photos/pcb.3025965137635511/3025964957635529/?type=3&theater and https://business.facebook.com/fundacionrewildingchile/photos/pcb.3025965137635511/3025964964302195/?type=3&theater