The evolutionary history of giraffes is proving to be intriguing. A recent discovery revealed a 15 million-year-old ancestor, named after Queen Amidala from the Star Wars prequels, had an unusual three-horned head ornamentation. Now, a team of researchers has used advanced reconstruction techniques to build a 3D virtual model of another giraffe relative. As revealed in the journal Biology Letters, this beast was an incredibly heavy animal with flamboyant, curly horns flaring out from its skull.
The modern Giraffidae evolutionary group is represented by two living species: Giraffa camelopardalis, the long-necked giant we all know and love, and the smaller, stouter, and more modestly proportioned okapi (Okapia johnstoni). The fossilized remains of Sivatherium giganteum ("Shiva’s giant beast"), a distant relative of both, was first found at the base of the Himalayan foothills in India in the 1830s.
It was dated to have lived around the end of the Pliocene Epoch, 5.33 to 1.8 million years ago. While that much was known, the physical nature of S. giganteum has been less clear, as was when and why it eventually became extinct. Apart from a few landmark studies – which disagree on key points regarding the enigmatic animal’s physical characteristics – there has never been a truly comprehensive reconstruction of its skeleton.
As a result, S. giganteum was initially misidentified as representing a link between modern ruminants (deer, sheep, giraffes) – those with multi-compartmented stomachs – and the obsolete group “pachyderms,” which erroneously included several animals that actually belonged to distinct groups. This study, led by Christopher Basu of the Royal Veterinary College, U.K., aimed to precisely recreate the extinct animal using 26 fossil bones from three incomplete S. giganteum specimens – all of which were borrowed from the Natural History Museum in London.
The skeletal reconstruction of S. giganteum. The anatomy modeled from its modern relatives are shown in green (A). Its extra-skeletal tissue is modelled in (B). The black bar is equal to one meter (3.3 feet). Basu et al./Biology Letters
After sorting through the bones by hand and identifying which were missing, they were scanned into a digital software program that was used to assemble a 3D model of the ancient beast. The missing ribs, back, and pelvis were “virtually reconstructed using modern giraffe and okapi anatomy,” Basu told IFLScience.
The most likely skeletal configurations were then animated and modeled in a separate software package, and the body mass of the beast was estimated. Based on these simulations, S. giganteum would have stood about 1.8 meters (5.9 feet) tall at the shoulder.
Remarkably, this lumbering giraffe-like creature would have weighed 1.2 tonnes (1.32 tons). In comparison, the modern Okapi, which is also roughly the same height, weighs just a quarter of that. S. giganteum was, however, roughly the same weight as a giraffe. In addition to two large, curly horns on the top of the male S. giganteum skulls, each about 70 centimeters (28 inches) long, it also possessed two smaller, pointier horns just above its eyes.
It was far shorter than the modern giraffe, had a less elongated neck, very dense, thick legs, and a flat face. “It would have been an impressive and strong animal,” said Basu in a statement. “Its face would have looked very different from a giraffe. Giraffe's have very long, pointed skulls. Sivatherium had a very short, flattened skull.” At this weight and height, the researchers consider it to be the largest ruminant mammal ever to have roamed the world.
Its immense size may have meant that it struggled to find enough food to provide itself with sufficient energy. “You get to a certain point, as an animal, where your stomach isn't big enough to contain all the food to keep you going,” Basu noted to IFLScience. “Animals like that are very sensitive to changes in the environment around it.” Although it is decidedly unclear when this animal went extinct, it may have gone the way of the Dodo thanks to rapid climate change altering its food supply.
