Calling extant relatives of extinct species the same species of megafauna is interesting

No no, it’s that humans are technically in the fish group of evolution, even though it happened a LONG time ago. That’s what they mean by “cladistically”, there is no “clade” of fish. Look up “humans are hagfish by Clint’s Reptiles”. He explains it wonderfully

Could be carcinisation, no sirree

Actually, it really is just a single metacarpal bone. The others are the red square bones you see up top, they are vestigial at this point. Like how whales have legs, we just can’t see them