I hope I can take this opportunity to ask for clarification? I’ve seen this ‘novel body plan’ phrase used before, but never seen any explanation other than ‘with features like a wing, or an eye.’
As someone who grew up in the mindset of evolution, it seems obvious to me that a cat and a dog, for example, have the same fundamental body plan: four legs, ears, tail, fur, etc. On the other hand, you probably aren’t referring to the body plan of having a mouth, digestive tract, and anus; that’s most animals except sponges and jellyfish, and it wouldn’t make much sense to claim common descent for them but not other groups.
So, if we use the example of a wing, does that mean all birds follow the same body plan, and therefore could be an example of common descent? But what about an eye? That goes back way farther (in the evolutionary view), before the divergence of mammals, birds, reptiles, fish, and sharks. I admit that I’m really confused by this argument.
Would creationists say that humans and apes exemplify ‘novel body plans?’ It seems to me that, although we can list a great many differences between our species, the vast majority of them are not so much novel features as differences in proportion: apes have shorter legs, longer arms, smaller brains, more hair, etc. What is there that’s truly new, without getting into philosophizing?
I’m genuinely trying to understand this rather than just poke at a touchy subject for the sake of it. I hope if it’s been discussed in more detail elsewhere, someone might link me?