With ground pressure like that, this croc would not be able to scramble up a muddy river bank very well. Maybe sand and shale, but not mud. This would limit its ability to hunt by lying in ambush for animal to come near a water source. But if the prey animals came to a shallow, sloping pool, this croc (given it's size) could never sneak up on it. Nor could it catch the prey if the animal scrambled up the bank.
Maybe this animal went extinct due to mobility problems.
I saw an astonishing video clip on a nature show a few months back. A herd of Wildabeast (not H, come on now) were drinking at the edge of a pool. The cameraman knew a large croc was in the area and was hoping for some action. Telltale bubbles gave away the crocs position as he snuck up on the Wildebeast (stocky animals about the size of Elk?)
Suddenly that monster came charging out of the water, rearing up on its hind legs, grabbed the head of an adult Wildebeast, and threw it over its head and into the swamp. Dangdest thing I ever saw. If a present day croc can take down a 300 - 400 pound animal with such ferocious power, that old timer must have been one he$ll of a hunter.
Probably could not take a T-Rex though.