Colours of Wildlife: Three More Sparassodonts
Created | Updated Sep 6, 2020
Three More Sparassodonts
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Today I give you, for the same low, low price, THREE critters instead of one! And to boot, they're extinct, so you won't find them in the 'real' world. These are: Arctodictis munizi, Callistoe vincei, and Proborhyaena gigantea. These continue my series of articles about the Sparassodonts: I've already done Borhyaena, Cladosictis, and Thylacosmilus. Those three represent basically dog, mongoose, and sabretooth-cat-like members of the group. The ones we feature today, represent more compact, badger-to-bear-like sparassodonts.
Just to recap, in case you don't have time for those other articles: sparassodonts were prehistoric mammals that only occurred in South America and briefly in Antarctica when those two continents were connected. For most of the time of the Age of Mammals, South America was not connected with North America, and the animals there followed wholly independent lines of evolution, resulting in groups of animals there that were totally unique (except for occasionally being shared with Antarctica as said above). In the realm of the mammals, these included our old sparassodonts. They became the dominant mammalian predators in South America during its 'island continent' phase. (So far, they haven't been found in Antarctica.) They shared the stage as top predators with non-mammals such as the Terror Birds. The name 'sparassodont' means 'tearing tooth'. The sparassodonts included small to large kinds, and as I hope you'll have gathered by now, quite a diversity of body shapes and ways of life. This illustrates the amazing creativity of evolution and the 'malleability' of animals' physical bodies over many millennia to adapt and change and manifest in new modes. The similarity between sparassodonts and our modern predators show though that there are also in nature some 'standard' ways of life, niches, gaps in the food webs, that call for similar shapes and that get filled by whatever is there to rise to the challenge. The manifestation of such common forms in species that are only distantly related, is called 'convergent evolution'. Sparassodonts flourished in South America for millions of years but then mysteriously went extinct some time before the invasion of South America (made possible by the forming of the bridge with North America through the isthmus of Panama) by modern carnivorans like wolves, dogs, foxes, bears and cats.
Remember also that sparassodonts were not placental mammals; they did not carry their babies inside their bodies for very long. Lacking a placenta to feed it, the sparassodont embryo was unable to grow and was ejected very early in its development, to continue its growth outside the mother's body but sheltered likely by a pouch as in modern marsupials. We do not know the details of their reproduction though. They were not in the same order as modern marsupials, so there might have been some significant differences in their reproductive ways.
Good, lets look at today's three representatives of this ancient group. The first is Arctodictis munizi. Its name means 'Muniz's bear-weasel'. This was a compact, powerful and quite large animal, reaching or even exceeding 50 kg/110 lbs in bodyweight. Its body was carried low on its short but sturdy legs, walking with the soles of its feet flat on the ground, like a bear. Its skull was short, wide and strongly built. Its teeth were large and thick, and it might have been able to crunch bones like a modern hyena. It probably filled the role of generalist forest predator and scavenger, relying on strength and surprise, rather than speed, to catch its prey. Arctodictis lived in the Miocene about 17-16 million years ago.
Our next old critter is Callistoe vincei. I based my reconstruction on a beautiful, almost complete fossil of this species found in Argentina. I reckon the name 'Callistoe' comes from the word meaning 'beautiful' in Greek. Callistoe is one of the oldest known sparassodonts, living in the Eocene period about 50 million years ago. Nevertheless, it is an already highly evolved and specialized sparassodont. Callistoe was medium-sized but powerful, reaching about 23 kg/50 lbs. Its skull was rather narrow, and somewhat fox-like. In overall build it was rather like a wolverine. Its robust forelimbs seem to have enabled it to dig well. It had canine teeth with open roots, meaning they kept growing throughout its life. But constant wear likely kept them from getting inconveniently long. Callistoe was a close relative of the next species.
So, the last species for today is Proborhyaena gigantea. The scientific name means 'gigantic pre-Borhyaena', referring to it predating its more well-known relative Borhyaena. It was not a close relative, though, belonging to a different family, along with Callistoe and a few others. Proborhyaena was the largest known sparassodont. Some estimates placed its weight as up to 600 kg/1300 lbs, but this is probably exaggerated; more realistically, it might have reached 200 kg/440 lbs, the size of an average bear. It is known from some skull remnants, suggesting a skull length of 50-60 cm/20"-24". Like Callistoe, it had ever-growing canine teeth, and its robust cheek teeth suggest that it would also have been able to crunch bones like Arctodictis. A creature of its size could have hunted some of the largest herbivorous mammals of the time such as Pyrotherium. It might have scared smaller carnivores away to steal their kills, and it also might have scavenged. Proborhyaena lived in the Oligocene period, about 30-20 million years ago.
