Occipital horn-tufts: a previously overlooked feature of (certain) giraffes

It is well-known that the horns of giraffids are unlike those of deer or bovids, in being permanent, skin-covered, and adorned by tufts of hair instead of points.

So who would have expected zoologists to keep overlooking features as obvious - and with as much taxonomic significance - as secondary horn-tufts? And on animals with as high a profile as giraffes?

And yet these have indeed been overlooked.

Giraffes possess a main pair of horns, which are tufted in juveniles but become bald in adults, particularly males. However, they also potentially possess an additional pair of horns, located at the posterior edge of the cranium. This is the occipital part of the skull, just above the nape (e.g. https://pixabay.com/photos/giraffe-profile-close-up-830532/).

The occipital horns develop only in mature males, only in some of the species of giraffes, and only in some individuals. However, it is in their undeveloped (incipient), not developed, condition that the occipital horns bear small tufts, which can clearly be seen in many photos (e.g. https://www.dreamstime.com/wild-giraffe-profile-image-south-african-wild-close-up-giraffe-profile-south-africa-wild-image156441687).

It is these additional horn-tufts that have escaped notice, as far as I know by everyone.

The occipital horn-tufts are located close to the top (distal extreme) of the mane. So in profile view they might be assumed to represent nothing more than the end of the mane. However, they are actually distinct in both position and tone (https://www.istockphoto.com/photo/giraffe-in-kennya-on-safari-africa-gm1354463380-429280885 and https://fineartamerica.com/featured/i-see-you-if-i-dont-even-look-at-you-giraffe-portrait-zina-stromberg.html). Unlike the brown of the mane, the occipital horn-tufts are always blackish (https://www.dreamstime.com/royalty-free-stock-photography-giraffe-profile-image7086897).

The occipital horn-tufts are most obvious in adult females, and they are clearest in Giraffa tippelskirchi. They are small in Giraffa giraffa, and vestigial or absent in Giraffa camelopardalis and Giraffa reticulata.

GIRAFFA TIPPELSKIRCHI:

Because the occipital horn-tufts distinguish between different types of giraffes, they are useful taxonomically. They indicate that G. tippelskirchi is more closely related to G. giraffa than to G. camelopardalis, an affinity also borne out by pedal and laryngeal flags (see https://www.inaturalist.org/journal/milewski/48447-conspicuous-features-of-colouration-in-giraffes#).

One of the clearest illustrations on the Web is https://www.pond5.com/stock-footage/item/75223817-masai-giraffe-chewing-maasai-mara-kenya-Africa. In this subadult female individual of Giraffa tippelskirchi, the occipital horn-tufts are almost as long as the tufts on the tips of the main horns.

However, even in females of G. tippelskirchi, the occipital horn-tufts are subject to individual variation: https://fineartamerica.com/featured/maasai-giraffe-jeffrey-c-sink.html and http://www.oceanlight.com/spotlight.php?img=29974 and https://fineartamerica.com/featured/maasai-giraffe-eating-acacia-leaves-serengeti-ross-warner.html and https://www.dreamstime.com/baby-giraffe-trees-background-giraffes-world-s-tallest-mammals-thanks-to-their-towering-legs-long-necks-alone-image200452303 and https://www.istockphoto.com/search/2/image?page=7&phrase=masai%20giraffe.

One of the peculiarities of the occipital horn-tufts is that they are neither masculine nor precocial.

In giraffes, the main horn-tufts are so precocial that they are present at birth, and are proportionally larger in infants than in adults. However, this does not apply to the occipital horn-tufts, as shown in the following of Giraffa tippelskirchi:

adult female with neonates/infants:
https://www.dreamstime.com/stock-photos-mom-giraffe-her-baby-savanna-image15611253 and https://www.shutterstock.com/nb/image-photo/gorgeous-touching-moment-mother-giraffe-takes-1989333311 and https://www.istockphoto.com/photo/masai-giraffe-gm1257170489-368333298 and https://www.dreamstime.com/adult-giraffe-watches-over-calf-giraffe-nursery-savannah-adult-giraffe-watches-over-calf-giraffe-image124421523 and https://www.dreamstime.com/royalty-free-stock-photography-mom-giraffe-kiss-her-baby-image15611237 and https://www.dreamstime.com/giraffe-mother-calf-standing-plains-masai-mara-national-reserve-giraffe-mother-calf-standing-great-image190720043 and https://www.dreamstime.com/stock-photo-female-giraffe-baby-savannah-kenya-tanzania-east-africa-excellent-illustration-image78933000

infants:
https://www.shutterstock.com/nb/image-photo/close-masai-giraffe-nibbling-on-thornbush-1939699015 and https://www.dreamstime.com/close-up-baby-masai-giraffe-watching-camera-image213135920 and https://www.dreamstime.com/stock-photo-masai-giraffe-calf-tail-flicking-young-its-savanna-mara-kenya-baby-s-umbilical-cord-still-visible-making-image83750176 and https://www.dreamstime.com/giraffe-zebras-newborn-giraffe-mingles-mother-zebra-her-foal-image108548253 and https://www.agefotostock.com/age/en/details-photo/close-up-of-a-masai-giraffe-giraffa-camelopardalis-tippelskirchi-also-known-as-the-maasai-giraffe-or-kilimanjaro-giraffe/X5T-2549599.

The above photos show that, although the occipital horn-tufts are present at birth, they are not proportionately large in infants in the way that the main horn-tufts are.

The following are further illustrations in Giraffa tippelskirchi:

https://www.istockphoto.com/photo/two-giraffe-gm599765514-102984869

second photo in https://www.loe.org/blog/blogs.html?seriesID=65&blogID=43

https://www.dreamstime.com/masai-giraffe-profile-closeup-isolated-studio-shot-facing-left-his-mouth-open-tongue-beginning-to-protrude-white-image186124860

https://www.alamy.com/stock-photo-masai-giraffe-up-close-140383640.html

https://www.dreamstime.com/stock-photo-masai-giraffe-eating-acacia-aka-kilimanjaro-maasai-kenyan-leaves-its-long-grey-tongue-wrapped-image83752427

https://www.projectnoah.org/spottings/8674285/fullscreen

https://www.dreamstime.com/giraffes-world-s-tallest-mammals-thanks-to-their-towering-legs-long-necks-giraffe-s-legs-alone-taller-than-many-image200452329

The following show that the occipital horn-tufts disappear in adult males, even in G. tippelskirchi:

adolescent males:
https://www.istockphoto.com/photo/masai-giraffe-gm467510293-34473716
https://fineartamerica.com/featured/masai-giraffe-closeup-ivan-kuzmin.html

adult male:
https://www.agefotostock.com/age/en/details-photo/closeup-of-masai-giraffe-scientific-name-giraffa-camelopardalis-tippelskirchi-or-twiga-in-swaheli-image-taken-on-safari-located-in-the-tarangire-national/ESY-045336775

GIRAFFA GIRAFFA:

The following show that, in G. giraffa, the occipital horn-tufts are usually small but are usually discernible by their blackness. The best-developed example I have found is the following: https://depositphotos.com/279388852/stock-photo-wildlife.html.

adult females:
https://www.dreamstime.com/head-giraffa-isolated-white-background-head-giraffa-isolated-image147209689 https://www.shutterstock.com/nb/image-photo/south-african-giraffe-close-namibia-568255321
https://www.dreamstime.com/father-son-watching-feeding-giraffe-zoo-happy-kid-ha-father-son-watching-feeding-giraffe-zoo-happy-kid-image113118222
https://www.dreamstime.com/close-up-giraffe-front-some-green-trees-looking-camera-portrait-giraffe-head-against-green-background-image234436382
https://fineartamerica.com/featured/-tourist-watching-giraffe-giraffa-david-santiago-garcia.html
https://www.offset.com/photos/close-up-portrait-of-giraffe-giraffa-camelopardalis-baring-teeth-in-269870
https://www.gettyimages.ie/detail/photo/giraffe-closeup-royalty-free-image/892339092?adppopup=true

juvenile female: https://www.istockphoto.com/photo/portrait-of-a-giraffe-gm1248182797-363495609

juvenile/adolescent males:
https://www.dreamstime.com/giraffe-profile-eyes-giraffe-profile-eyes-closeup-wildlife-image148755686
https://www.dreamstime.com/stock-photo-little-boy-feeding-giraffe-zoo-day-time-image46341041
https://www.shutterstock.com/nb/image-photo/giraffe-on-safari-chobe-national-park-1487855891.

The following show that the occipital horn-tufts are absent in adults of G. camelopardalis, even in females: https://www.shutterstock.com/nb/image-photo/close-view-giraffe-head-behind-brown-1554923213 and https://www.alamy.com/stock-photo-a-single-giraffe-profile-closeup-against-a-bright-blue-sky-39860494.html and https://pxhere.com/en/photo/1271059 and https://fr.dreamstime.com/photo-stock-profil-d-t%C3%AAte-girafe-image45463715 and https://www.dreamstime.com/stock-photo-giraffe-head-profile-s-isolated-background-image77327021 and https://www.austockphoto.com.au/image/giraffe-close-up-side-view-bidOS and https://snappygoat.com/free-public-domain-images-giraffe_male_animal_head_0/TV8x2YVx0HyL_HdJArEIjIT4-hY9pBBtuOySKGxbpzQ.html#,0,156 and https://www.dreamstime.com/stock-photos-giraffe-head-image335733.

GIRAFFA CAMELOPARDALIS:

The only evidence of occipital horn-tufts in G. camelopardalis is a trace in some individuals, and even these are doubtful because of possible hybridisation:

adult females:
https://www.dreamstime.com/stock-photos-reticulated-giraffe-portrait-image16544343
https://www.gettyimages.com.au/detail/photo/reticulated-giraffe-royalty-free-image/1280894242?adppopup=true

juveniles:
https://www.dreamstime.com/stock-photo-beautiful-side-profile-giraffe-wild-image77492366
https://www.shutterstock.com/nb/image-photo/giraffe-portrait-head-close-2040205991

infants:
https://dallas.culturemap.com/news/city-life/06-19-19-zoo-baby-giraffe-death-witten-anesthesia-canadian-zoo/
https://www.dreamstime.com/royalty-free-stock-photos-young-giraffe-eating-close-up-leaves-image40437778

The following show hybrids between G. camelopardalis and G. reticulata: https://www.dreamstime.com/stock-photo-reticulated-giraffe-profile-isolated-image-head-viewed-image87307138 and https://www.dreamstime.com/stock-images-reticulated-giraffe-portrait-image17151984 and https://www.shutterstock.com/nb/image-photo/artiodactyl-mammal-giraffe-family-giraffes-head-2048048231 and https://www.dreamstime.com/stock-photo-profile-young-reticulated-giraffe-head-side-image45800720 and https://es.123rf.com/photo_11772370_baby-giraffe-high-detail-profile.html and https://es.123rf.com/photo_11353011_jirafa-beb%C3%A9-perfil.html.

GIRAFFA RETICULATA:

The following shows the absence of occipital horn-tufts in this species:

infant (including video): https://www.localmemphis.com/article/life/animals/too-cute-memphis-zoo-welcomes-new-giraffe-calf-to-the-family/522-c23b26ce-bb79-488f-b02b-71a8db3e56ac

juvenile female: https://www.dreamstime.com/stock-photo-reticulated-giraffe-head-side-profile-view-young-image58518677

mature male: https://www.gettyimages.com.au/detail/photo/reticulated-giraffe-eating-acacia-leaves-samburu-royalty-free-image/86070775?adppopup=true.

In summary, the occipital horn-tufts are taxonomically useful because they are negligible in the northern and western forms while being present in the southern and eastern forms, particularly the latter.

Posted by milewski milewski, November 21, 2021 23:24

Comments

The following, of Giraffa tippelskirchi, shows that the occipital horn-tufts are like the tail-tassel in not being precocial: https://www.dreamstime.com/royalty-free-stock-image-young-giraffe-mother-his-giraffa-camelopardalis-serengeti-national-park-tanzania-image32067726.

Posted by milewski 6 months ago (Flag)
Posted by milewski 6 months ago (Flag)

The following, of infant Giraffa tippelskirchi, shows that at birth the main horn-tufts are fully-developed but the occipital horn-tufts are hardly noticeable: https://www.pbs.org/wnet/nature/files/2008/09/na_img_tblond_girtran1.jpg. Compare this with the following adult females: https://www.istockphoto.com/photo/giraffe-gm1201664648-344706013 and https://www.istockphoto.com/photo/giraffe-with-bird-gm669764382-122873117, and the following elderly female : https://www.istockphoto.com/photo/giraffe-gm1196976314-341594907.

Posted by milewski 6 months ago (Flag)

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