About the size of a horse but bulkier, I'd be treating it as about 5HD in D&D. It would have moved more or less like a mammal. It's a synapsid, so part of the same great clade as mammals and probably would have walked like a mammal of the same sized. Built rather closer to hippo, but with great forelimbs and probbaly a habit of headbutting as a means of resolving dominance. Might have lived its life part in water, and pretty certainly ate tough, fibrous plant matter.
Moschops has been extinct for 260 million years, it was a Permian creature. Which means it's almost as out-dated as the dress sense of the lady in this image from Wikipedia.
A whole permian era ecology would be very, very alien to any PC's finding themselves among it. And I suspect Moschops, and creatures like it, would be numerous therein. I'll maybe stat this one up fully for BECMI later.
Moschops
by Cab Davidson
| Stat | Moschops |
| AC: | 5 |
| HD: | 4+2* |
| Movement: | 150' (50’) |
| Attacks: | 1 headbutt or 2 claws/1 bite |
| Damage: | 2d6 or 1d4/1d4/1d6 |
| No. Appearing: | 0 (4d4) |
| Save As: | F2 |
| Morale: | 8 |
| Treasure Type: | 0 |
| Intelligence: | 1 |
| Alignment: | Neutral |
| XP Value: | 175 |
Moschops is a heavy, thick-set creature from the Permian period, well before the age of the dinosaurs. It is around 9’ long, 5’ high at the head, possessing thick, muscled legs that sit almost beneath their barreled body and they have a short, tapered tail. Thick skin on and around their forequarters ends in a thick pad on their heads, with which they can attack a foe if they have the opportunity to charge before they attack. With this charge attach they can inflict double damage. They can also rear up onto their hind legs to deliver raking attacks with their claws, or bite an enemy with tough, peg like teeth that are usually used for long grinding of the toughest plant matter.
They typically form small herds of 4d4 individuals, but can congregate into much larger groups if grazing conditions are right.