Comment on Endoceras by AStepIntoOblivion
I like this picture, both artistically and for providing an alternative interpretation of Endoceras that's more nautilus-like than squid-like. Might I borrow the image for a slide in a public presentation? I would of course provide credit to you as the artist.
Regarding the affinities of cephalopods - the resemblance of bactritids to orthoconic nautiloids is more than superificial; bactritids evolved from orthocerids. While it may be a mistake to assume all Paleozoic nautiloids had anatomy like coleoids, we also cannot assume they all resembled the modern nautilus, which is itself specialized and might just as likely have evolved its numerous arms from a smaller number of arms in the ancestral cephalopod. Given the great diversity of form we see among Ordovician nautiloids, it's likely they were a lot more varied than what we see among coleoids and nautilus today. Given our uncertainty about these animals known only from shells, an interpretation such as this one has value.
Regarding the affinities of cephalopods - the resemblance of bactritids to orthoconic nautiloids is more than superificial; bactritids evolved from orthocerids. While it may be a mistake to assume all Paleozoic nautiloids had anatomy like coleoids, we also cannot assume they all resembled the modern nautilus, which is itself specialized and might just as likely have evolved its numerous arms from a smaller number of arms in the ancestral cephalopod. Given the great diversity of form we see among Ordovician nautiloids, it's likely they were a lot more varied than what we see among coleoids and nautilus today. Given our uncertainty about these animals known only from shells, an interpretation such as this one has value.
very good point! I am still impressed by this picture, as it shows an independent line of thinking, and despite the fact that the nautilus may very well be specialized in some ways, it is still a better guess to make than than making it look like a squid in a cone. Sort of like latimeria. it may very well be specialized in its own ways, but it still can help us better understand what fossil species probably looked like, it can even give insight on soft tissue anatomy, even if not in the details, the general structure we see today would be similar to the preexisting one, even though the preexisting species may have added a few unique twists of their own to it.
I think this picture is very well done. sure, it is still speculative, but the speculations made seem very reasonable. When you look at it, it doesn't even look exactly like a nautilus, it looks more primitive than that. like you said, the number of arms/tentacles may have been variable, for example, so this is not a perfect or an exactly correct reconstruction, but given what we know about cephalopods and phylogenetic bracketing, this is miles closer to what these animals most likely looked like than any "squid in a cone" reconstruction could ever dream about.
I think this picture is very well done. sure, it is still speculative, but the speculations made seem very reasonable. When you look at it, it doesn't even look exactly like a nautilus, it looks more primitive than that. like you said, the number of arms/tentacles may have been variable, for example, so this is not a perfect or an exactly correct reconstruction, but given what we know about cephalopods and phylogenetic bracketing, this is miles closer to what these animals most likely looked like than any "squid in a cone" reconstruction could ever dream about.