The plant-eating therapsid Moschops may look pretty tame, but don't be fooled. Moschops had powerful legs and very thick skull bones on the top of its head. The therapsid of the Permian Period possibly used its thick skull to head-butt other Moschops, the way some modern-day goats do. The name Moschops Means "Calf Face". It is around 16 feet long ( 5 metres ) and weighs around a ton.