Maybe, but I wouldn't bet on it.

A well-conditioned horse is a truly amazing animal. Remember, that critter carried a man in addition to itself and beat the gemsbok on the gemsbok's home turf. I have chased elk and deer on horseback for kicks here, and the only thing that stops the festivities is timber...once the elk gain the dense timber it's over. On the flats you might be surprised. Most game animals have tremendous burst capacity but wear out over distance fairly quickly. Funny thing is that for some reason I would expect animals in the oryx family to possess really outstanding stamina. Maybe not compared to a good horse?

Guessing is hard tho. For example, bear look ungainly but can run for days, literally. Cougar look like they can run but have no wind at all and hound races normally end within a half-hour or even less.

Hard to say what breed that critter is and what size, but unless the man is really tall it looks a bit like a Boerperd to me. I managed a couple of them when we lived in RSA and they were hardy cayuses.

Right now I have two quarter-horse crosses I'd stack up to a gemsbok though I'm not sure I would stack me the rider up to a gemsbok!

Larcher; do you know where this fellow stuck the gemsbok? As far as I have read, the classic stick is to knick the critter in the neck. It is all over pretty quickly just as it is when we stick butcher critters I'm sure. Aren't there still some clubs that ride down stag in France?

BTW: Looks like a Cold Steel "Bushman" knife stuck on that haft.