Comment by jyounker

> How did these animals survive as a species for millions of years with this flip-over bug in their genes?

Whether or not they can right themselves depends upon the terrain. Falling over can be a fatal experience for humans too.

> Why hasn't evolution solved it, for example, by eliminating flip-prone individuals from the gene pool and giving better survival chances to those who can right themselves?

Evolution is all about trade-offs. Being big makes it hard to right yourself, but it also makes you much harder to flip. It probably also probably makes you much hotter to potential mates.