Sarkastodon: Record holder for largest mammalian predator?
An Eocene contemporary of Andrewsarchus mongoliensis, and like Andrewsarchus and Megistotherium – a fellow creodont which roamed the North African plains of the Miocene epoch – contenders for the largest mammalian predator heavyweight crown, Sarkastodon were large and massively built creatures superficially bear like in appearance. Sarkastodon was a member of the family Oxyaenidae which is turn part of the creodont order.
Creodonts emerged during the late Cretaceous period but really came into their own during the Cenozoic era. Creodonts were the dominant predators from about 55 million years ago until 35 million years ago. The last known creodont, Dissopsalis, went extinct about 8 million years ago. Their cousins, the true carnivores such as modern wolves, cats and bears gradually supplanted them and now fill their ecologic niche.
Range and timeline:
The fossil record for Sarkastodon is at this time too scant to allow any definitive statement as to its range or even of its time span on earth. The fossils that we have are from a relatively small section of Mongolia. How broad the animals’ distribution may have been is a matter for speculation. We know that it lived during the Eocene epoch and that there are fossils extant dating from approximately 55 million years ago. It is believed to have gone extinct between 38 and 35 million years ago but this time scale is more of a working hypothesis than a rock ribbed fact.
Those fossils which are currently available indicate a massively robust bear shaped animal with singularly powerful jaw muscles and highly effective dentition. It seems to have been equipped with a long, raccoon like tail. Like all creodonts Sarkastodon had a plantigrade gait meaning that it ran flat footed rather than on its toes, and lacked a flexible leg design – specifically a rotating wrist joint. These factors would have limited its speed and agility, and coupled with a smaller brain size relative to the true carnivores may over time have contributed to the decline of the order.
Sarkastodon stood nearly seven feet tall at the shoulder, weighed perhaps as much as 3000 pounds and when reared up on its hind legs is estimated to have been able to have reached objects 19 feet off the ground with its outstretched paws. Its size, mass and power would have allowed it, in the opinion of some, to dispatch a full grown modern elephant.
While modern elephants were not available to Sarkastodon a wide variety of other large food sources were. The Brontotheres were abundant in Mongolia at that time, and these large rhinocerene relatives of the modern horse were certainly within the hunting capabilities of Sarkastodon. Chalicotheres were similarly prevalent, as were ancestors of the modern rhinoceros.
Sarkastodon is assumed to be a solitary hunter but there is no conclusive evidence to this effect. A pack or even a pair of these creatures cooperating on a hunt would have small difficulty making kills of the herbivores or lesser meat eaters of the times.
However, as is the case when many of the large extinct apex predators including Andrewsarchus and even Tyrannosaurus rex are being discussed there are dissenting voices that question whether Sarkastodon was primarily a predator at all. The argument seems to be that the sheer size and mass of the animal rules in favor of a scavengers life style coupled with opportunistic predation. While there is certainly room for debate it is worth mentioning that the presumed prey for all of these creatures, including heavyweights like the brontotheres and apatosaurs are large and not especially nimble, and could only be taken down by an equally robust and massive predator.
Science knows a little about Sarkastodon, more certainly than about contemporaries like Andrewsarchus or Megistotherium but little enough overall. It is hoped that more entries from the fossil record will yield further information on range, timeline, social habits, prey and all those other areas on which we currently can only speculate. The Eocene in general is a baffling epoch; there were many fascinating animals but few really widespread fossil beds known to do more than tease us about their lives.
Perhaps an illuminating discovery is just around the corner.