But have you ever thought about what an ammonite was? We still don't fully understand how colour-matching works in living cephalopods and it may be that ammonoids had a passive system that used mirror-like cells to help them match their background, rather than a system under active nervous control.Ammonites are probably one of the most recognisable and commonly collected fossils, with the majority of collections having some form of ammonites in their collection. From my own observations there may have been structures in some ammonoids that allowed colour change, but this would involve having parts of the body exposed close to the outside of the shell. The point of camouflage is to disrupt outlines and the 'search image' as much as to blend in with the background. This alone can be surprisingly effective. Their shells certainly had colour-banding, as in Nautilus. Nacre is widespread through the history of ammonoids, although it is more common in Cretaceous specimens since they have had less time to have their nacre stripped by geological processes. There has been much speculation on ammonoid diet, including cannibalism of older ammonoids on younger ones. An ostracod where we would expect the ammonoid crop to be is the only evidence for diet. There is no evidence for finding hooks that cannot be assigned to other taxa that I know of.ĭue to their closer relationship to squid, ammonoids are more likely to have had a complex eyeĭue to close relationship to squid, and also beds in the fossil record where apparent 'mass mortality' events are recorded it is thought that ammonoid probably only breed once then died.Īnother real unknown. Ammonoids probably lacked suckers and hooks. Two long-grabbing arms and eight sensory/prey-handling arms. On the basis of the similarity between squid, belemnites etc we think ammonoids probably had ten arms. The similarity of the external shell between ammonoids and Nautilus is only one character, which is apparently the result of convergence. On the grounds of 16 or so characters that ammonoids share with belemnites, squid and other living cephalopods we think that ammonoids are more closely related to these animals than Nautilus. I have to preface my remarks with the important information that we have very little actual evidence of ammonoid soft-parts, but we do know about the structure of their shells, the size of their eggs and the anatomy of their jaws. was on ammonoids, so I will try to answer your questions. Take your time responding if you need to.
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