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The Hoofed Predators
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Relating to Andrewsarchus, its prey range/skull usage seems to be very unlimited (it dug roots and tubers, killed large and slow embolodonts and elephant-like creatures, and pierced hard shells of various ocean creatures):
The exact diet of Andrewsarchus has also been questioned as the previous older apex predator theories don’t carry as much weight as they used to. Although the jaws would have had tremendously powerful muscles (as indicated by the size of the cheek bones), most of the teeth in the mouth are not particularly well adapted for any one purpose. The forward canines are the largest and are most useful for getting a grip on things, or perhaps in the case of a carnivore to deliver a killing bite such as puncturing the cranium of a prey animal. Because the type specimen skull was found in what would have been a coastal environment during the Eocene, Andrewsarchus has been presented as a beach comber. Here Andrewsarchus may have had a durophagus diet that means it ate shellfish that it dug out with its forward teeth, although it may have included animals like turtles as well as washed up carrion. However while this skull proves that Andrewsarchus was active in coastal areas, it would be a mistake to assume that it was limited to them without the evidence of further remains. Aside from the skull being similar in form this has also led to some claiming that the behaviour of Andrewsarchus was similar to what has been proposed for enteledonts. This would see Andrewsarchus living the life of an opportunistic omnivore, as while Andrewsarchus is on paper capable of killing its own prey, it may have scavenged carcasses as well as driven off other predators from their kills. The forward teeth could also have been capable of digging up plant tubers that Andrewsarchus could have then eaten. Since Andrewsarchus had a large skull it would need strong neck muscles to provide ample support. Although we still do not know for certain, it’s possible that the anterior dorsal vertebrae had enlarged neural spines (bony projections that rise upwards from the individual vertebra) that provided increased areas for muscle attachment. This is similar to how some other creatures with large skulls such as enteledonts supported their heads. If true then Andrewsarchus would in life have powerful powerfully built fore quarters which may have given rise to a small hump above its shoulders from the increased muscle mass from this area. More on Andrewsarchus. Judging from the skull's features, an average Andrewsarchus could graze grass like a hippo, slice/dice like a feline, scavenge like a bear, and bluntly bite like a mesonychid. It was a very adaptable creature in terms of food depletion, and I think it's safe to say that this creature was an omnivore as well, but the problem was its size. The early Eocene in Pakistan/Southern Gobi had its fair share of gas (specifically, carbon monoxide) lakes and major floodways unlike most other parts of the world at the time, so it wasn't a great surprise when the bigger and less maneuverable animals were wiped out due to these two factors. The most adaptable creatures in those areas were the primates and early whales. The primates could reach such high altitudes in the trees (since none were bigger than a meter and a half in Pakistan at the early Eocene period) to escape the dense monoxide gases bursting out of lakes and the floods as well. The early whales, with the exception of Pakicetus, would already swam their way out of the floodways and into the ocean, evolving into the array of cetaceans we see today. Andrewsarchus would've been comparable to a super-sized polar bear with large forequarters and neck and a muscular back. If put in today's environment, albeit at a much smaller size (~200 kg maximum), then I would put a grand bet on it to be thriving within areas with little carnivore competition, human defense, and a grand supply of large prey such as the Himalayas, Bengaladesh, and the Washington coast. 
I have to question the above article. First, am I correct in the statement we just have a single Andrewsarchus skull? Thus, postcranial morphology is missing.
I've looked around journal libraries and there is very little about Andrewsarchus. It seems it has recently been reclassified. Nonetheless, what a skull:  *This image is copyright of its original author
Whatever Andrewsarchus was, he was certainly a massive animal; likely an omnivore. http://jurassicgiants.blogspot.com/
(01-27-2016, 12:17 AM)tigerluver Wrote: I have to question the above article. First, am I correct in the statement we just have a single Andrewsarchus skull? Thus, postcranial morphology is missing. It's been reclassified as a carnivorous unglate instead of a mesonychid (relatives of Mesonyx.) Has anyone gathered any information about Daeodon yet? I'm researching into it.
Daenodon was an enteledont. His nearest living relative is the hippopotamus. He measured 3.6 meters long ( 11 feet 10 inches ) and stood 1.8 meters high ( roughly 6 feet ). He was either a pure carnivore or possibly an omnivore; very likely a scavenger.
http://www.prehistoric-wildlife.com/spec...eodon.html
Entelodonts (such as Archaeotherium) were not directly related to pigs; closer to hippos and whales. More to the point, they didn't need a particularly strong bite. The sheer weight of their skull required massive spines on the thoracic vertebrae, similar to bison; this resulted in a sledgehammer of a skull with vicious teeth adding to the damage. Even better, this also allowed for a "grip and rip" approach to killing, like a dog thrashing a squirrel to pieces. The irony being how canids like Hesperocyon ended up on the receiving end if they failed to pay attention.
Art by Mauricio Antón = https://www.facebook.com/groups/GApaleo/  *This image is copyright of its original author
Who was truly the biggest terrestrial mammalian predator? Daenodon, Andrewsarchus, or Arctodus simus?
(04-13-2016, 04:52 PM)brotherbear Wrote: Who was truly the biggest terrestrial mammalian predator? Daenodon, Andrewsarchus, or Arctodus simus? Last I checked A. angustidens (and A. simus if you go by the analyses posted in the other thread) are the largest mammalian predators ever. The other two species are really hard to get a mass estimate of. They're proportioned like no animal we know of today. Plus, we're missing significant long bone data on them.
@Polar,
Sorkin put that at 500 kg. Sarkastodon mongoliensis was the heaviest carnivore he estimated, at 800 kg. Sorkin's method were flawed significantly although. He used isometry, but chose the mass of a literature specimen and attached it to a specimen he measured himself in a museum. Isometry also won't work well the way Sorkin did it, as for instance, Megistotherium was being based off a tiger. The two are not proportionately equal.
Since Sarkastodon was around ~750 to 800 kilograms, and A.simus and A.angustidens being the largest carnivores in existence (till now, maybe matched with the Pleistocene Polar Bear), shouldn't the average weight for the two ursids meet at more than 800 kilograms on average? I always thought both short-faced bear species and the oxyaenid were the same weight?
Once, I was told that the biggest A.angustidens specimen was ~975 kg or about 2150 pounds, almost 100 pounds less than the largest bear ever found, the Kotzebue Polar Bear Giant. This could possibly mean that the Pleistocene polar bears and maybe some near-modern polar bears were/ still are the largest mammalian carnivores in existance.
A lot of prehistoric species we don't have a true "average" figure for. There are usually less than a handful of worthwhile specimens that certainly cannot properly represent the entire population. For A. simus, we fortunately do have a lot of bones and the average for males was likely 700-800 kg off the top of my head, but I might be remembering wrong. There is only A. angustidens specimens, so no average can be given here. I am not aware of how many Sarkastodon specimens there are to say anything on their averages.
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