If I had to choose, I have a few ideas.
-Spinosaurus. Long reach, not a ton of damage.
-Smilodon, the sabertooth cat. A short, stocky, heavy duty grappler
-Quetzalcoatlus. An airborne fighter.
-Mammuthus. The fluffy tank.
As for the original characters, I have a few ideas.
-Armadon. The not so fluffy tank, more defensive. Unchanged visually, though as the god of life he is adorned with flowers and vines.
-Sauron. Combination of rushdown and grappler, like TJ. Slowest character, but unmatched up close in terms of damage. A tyrannosaur just like before, but with an emaciated/distended gut and multiple rows of teeth, for he is the god of hunger.
-Diablo. Lots of fireballs and other fun projectiles. Visually akin to an Allosaurus put through the Cinder program, with internal flame glowing within their charred body, and lengthened eye horns to add to their status as god of destruction
-Chaos. A bit of Blanka and Akuma. Visually more similar to a baboon, with large fangs and beady eyes. Slightly zombified to show him as the god of decay.
-Blizzard. The love child of Sub-Zero and Glacius. Visually like a gentle, albino gorilla, his apparent wisdom a sign of his status as the god of virtue.
-Talon. Like Riptor, but minus fire with more crazy kicks. rushdown. Maintains the old look, but with a bit if a Native American vibe to emphasize their status as the god of survival.
-Vertigo. Zoning and manipulation. Maintaining the image of a cobra monster, but with a more feminine, Medusa-like figure. Lovecraftian influences would add to her status as the goddess of madness.