Article: Growth and function of spines in the Jurassic ammonite Aspidoceras

The structure, mode of growth, and possible function of the spiniform tubercles of the Upper Jurassic ammonite Aspidoceras are described and analysed. Their complex growth pattern is particularly suitable for the construction of long, delicate, hollow spines. These spines probably contained extensions of the mantle, which were in contact with the environment through openings at their tips. Their function is thus inferred to have been primarily sensory.