Good tidings and well-wishes!
I apoligize for the tardiness of this entry: I’ve been feeling a bit under the weather of late. In consequence, this ‘Wednesday Wonder’ will be slightly shorter than normal, as I haven’t been able to accumulate as much information concerning this week’s creature as I generally have for previous animals.
Often in the course of a group’s evolution, creatures are produced which appear to be completely misidentified as some of its members. After all, who would have believed that modern crocodilians evolved from small, greyhound-like predators were it not for the findings of comparative anatomy which binds them together? Frequently, the cause of this disbelief resides in the unfortunate fact that many once diverse and successful groups have been reduced to a few scattered species in the modern world. This brings us to Sivatherium, a giraffid which for all the world looked (and probably behaved) like a moose.
Giraffids are ruminants and members of the infraorder Pecora along with deer, musk deer, pronghorns, cattle, goats, sheep, and antelopes. RJG Savage and MR Long write in their compendium “Mammal Evolution: An Illustrated Guide” that “The first pecorans appear in the eary Miocene of Europe and Africa and are difficult to assign to family status, hence the origin of the three main lineages (giraffes, deer and cattle) remains obscure.” The earliest creature which demonstrates strong giraffoid affinities is Climacoceras sp. from the Miocene of Kenya. It’s relations are suggested by its well-developed branch-like ossicones. The giraffids flourished during the Miocene and Pleistocene, their range extending through much of the Old World and most notably including central to northern Africa and most of India.
Standing with a shoulder height of 2.2 meters, Sivatheriumwas enormous by giraffid standards. A resident of modern day India, it’s sizeable proportions and very recent age qualify it as a member of the Pleistocene megafauna. In “The Evolution Of Artiodactyls” (edited by Don Prothero), Nikos Solounias writes:
“Sivatheriumwas… similar to the okapi, but it was a very large ruminant. With respect to diet, the giraffe is a browser, and the okapi may be either a browser or a fruit browser. The extinct taxa [Samotherium, Palaeotragus, and Sivatherium] were mostly browsers or mixed feeders but rarely grazers.”
In “The Ecology Of Browsing and Grazing”, Iain Gordon and Herbert Prins note of Sivatherium that the creature’s “Cheek teeth were generally more hypsodontthan giraffines, indicative of a more mixed-feeding type of diet.” While this is likely true and Sivatherium almost certainly grazed on occasion, much of its anatomy shows a large bias towards the browsing behaviors traditional in its family. It probably sported a short proboscis-like upper lip, which added yet another similarity to a modern moose and likewise would have assisted it in gathering branches and leaves. It’s also possible that Sivatherium possessed a long, prehensile tongue as modern giraffids do and which would have presumably been similarly dark purple in coloration to avoid the effects of sunburn.
It occurs to me that I’ve proclaimed how moose-like Sivatherium was several times without mentioning the most obvious trait warranting of this description: it’s enormous posterior ossicones. Savage and Long report that “This gigantic giraffid[‘s] skull (length 70 cm) had in male specimens a conical pair of ossicones above the orbits and a large palmate [(leaf-shaped)] pair behind the parietal bones.” The creature’s almost disproportionately-large and heavy head would have been supported in life by its fairly strong forelimbs which were comparatively shorter than those of a moose but comparable to an okapi’s.
May the fossil record continue to enchant us all.