I can "see" a full bull facing right, the front legs are the neck in my drawing, but the rear legs are missing. Is that what you see? Anyway, the caption of the image says

> The painted head of an auroch, an extinct wild bull, was the first painting archaeologists discovered in the cave.

so I think it's only the head.

The other drawings are also only the head, so it may be a local style/preference (???).