Primitive Saddle Challenge! Ark Survival Ascended: Alpha Megapithicus

Building a boss fighting army can be one of the most daunting experiences on The Island. The Ark is unforgiving; failure will cost you everything. So, I want to provide you with information that helps you assess whether or not your own army is up to the job.
In this video, I send my rexes against Alpha Megapithicus with only primitive saddles equipped. They are not supported by either myself or a yuty. How far will they get?

[@woldywonder]

I wouldn't have dreamt this was possible!

[@ZedsArk]

Next up - spider and dragon. I suspect spider will kill a few megatherium (but I've found a better breeder, so no great problem there).
I think dragon might annihilate the theris...