Suppose we have an alternate earth where there in addition to the real species on earth are large hexapod creatures similar to mammals and reptiles.
Where on the evolutionary tree is it most likely that they branched of from and why.
I came up with the following ideas but feel free to propose others.
- The early ancestor to lobe finned fish before the number of limbs was fixed in evolution.
- Flying fish transforming their wings and other fins to legs in convergent evolution.
- Early vertebrate fish evolved another fin layout more amenable to evolving into six legs
- Convergent evolution from some ancestor to insects evolving an internal skeleton
- Early reptile evolving toes into legs and then re-evolving toes/fingers.
Edit: My intent by similar to mammals and reptiles was that they should be a group of creatures with internal skeletons ranging in sizes from tiny like a mouse to huge like at least a rhino and competing for the same ecological niches.