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The Giraffidae are a family of ruminant artiodactyl mammals that share a recent common ancestor with deer and . This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant genera, the giraffe (between one and eight, usually four, species of Giraffa, depending on taxonomic interpretation) and the okapi (the only known species of Okapia). Both are confined to sub-Saharan Africa: the giraffe to the open , and the okapi to the dense rainforest of the Congo. The two genera look very different on first sight, but share a number of common features, including a long, dark-coloured tongue, lobed canine teeth, and horns covered in skin, called .
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The ancestors of pronghorn diverged from the giraffids in the Early Miocene. This was in part of a relatively late mammal diversification following a climate change that transformed subtropical into open savannah .
The fossil record of giraffids and their stem-relatives is quite intensive, with fossil of these taxa include Gelocidae, Palaeomerycidae, Prolibytherium, and Climacoceratidae.
Below is the phylogenetic relationships of giraffomorphs after Solounias (2007), Sánchez et al. (2015) and Ríos et al. (2017):
Family Giraffidae J.E.Gray, 1821
Giraffids share many common features with other ruminants. They have cloven hooves and , much like bovids, and a complex, four-chambered stomach. They have no upper or upper canines, replacing them with a tough, horny pad. An especially long diastema is seen between the front and cheek teeth. The latter are selenodont, adapted for grinding up tough plant matter. Like most other ruminants, the dentition for giraffids is . Giraffids have prehensile tongues (specially adapted for grasping).
The extant giraffids, the forest-dwelling okapi and the savannah-living giraffe, have several features in common, including a pair of skin-covered horns, called ossicones, up to long (absent in female okapis); a long, black, prehensile tongue; lobed canine teeth; patterned coats acting as camouflage; and a back sloping towards the rear. The okapi's neck is long compared to most ruminants, but not nearly so long as the giraffe's. Male giraffes are the tallest of all mammals: their horns reach above the ground and their shoulder , whereas the okapi has a shoulder height of .
(2025). 9780801887352, The Johns Hopkins University Press. ISBN 9780801887352 (2025). 9788496553774, Lynx Ediciones. ISBN 9788496553774 It is thought that the palaeomerycids, prolibytherids, climacoceratids and the giraffids all form a clade of pecorans known as Giraffomorpha. The relationship between the climacoceratids and giraffids is supported by the presence of a bilobed canine, and have been postulated into two hypotheses. One is the climacoceratids were the ancestors of the Sivatheriinae, as both groups were large, deer-like Giraffoidea with branching antler-like , while an extinct basal group of giraffoids, Canthumerycinae, evolved into the ancestors of Giraffidae. Another more commonly supported hypothesis is climacoceratids were merely the sister clade to giraffids, with sivatheres being either basal giraffids or descended from a lineage that also includes the okapi. While the current range of giraffids today is in Africa, the fossil record of the group has shown this family was once widespread throughout of Eurasia.
Classification
Below is the total taxonomy of valid extant and fossil taxa (as well as junior synonyms which are listed in the brackets).
Characteristics
The giraffe stands tall, with males taller than females. The giraffe and the okapi have characteristic long necks and long legs. Ossicones are present on males and females in the giraffe, but only on males in the okapi.
(2025). 9781408122518, A. & C. Black. ISBN 9781408122518
Distribution
The two extant genera are now confined to sub-Saharan Africa. The okapi is restricted to a small range in the northern rainforest of the Democratic Republic of Congo. Although the range of the giraffe is considerably larger, it once covered an area twice the present size – all parts of Africa that could offer an arid and dry landscape furnished with trees.
Behavior
The social structure and behavior is markedly different in okapis and giraffes, but although little is known of the okapi's behavior in the wild, a few things are known to be present in both species:
Giraffes are sociable, whereas okapis live mainly solitary lives. Giraffes temporarily form herds of up to 20 individuals; these herds can be mixed or uniform groups of males and females, young and adults. Okapis are normally seen in mother-offspring pairs, although they occasionally gather around a prime food source. Giraffe are not territorial, but have ranges that can dramatically vary between – – depending on food availability, whereas okapis have individual ranges about in size.
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