Getting unhooked: comment on the hypothesis that heteromorph ammonites were attached to kelp branches on the sea floor, as proposed by

The hook-like shape of heteromorph ammonites has puzzled scientists for years. In such ammonites, including those in the family Scaphitidae (called scaphites for short), the body chamber consists of a shaft, beginning near the last septum and a hook terminating at the aperture (Fig. 1). The point at which the hook curves backward is called the point of recurvature. In primitive members of the Scaphitidae, such as Scaphites , the hook is well developed with a large gap between the phragmo- cone and body chamber (Fig. 2A, B). In more derived members of this group, for example, Hoploscaphites , the hook is reduced, but a small gap is still present between the phragmocone and body chamber (Landman et al. , 2010: fig. 49). the hook-like shape of ammonites an adaptation for stationary attachment to the branches of kelp on the sea Ancyloceratidae, m its the inner surface of the shell, (2) of (i.e. symmetry) living of (3) of the and living chamber (4) location of epizoan on the the final stage of heteromorph ammonites of the suborder living