Reproductive biology and anatomy of ammonites

Abstract

Abstract Ammonoid anatomy is still poorly known and every new record of a specimen with soft tissue-preservation yields valuable information. In view of the impressive morphological disparity of ammonoids, we can also expect some disparity in soft tissue anatomy. Here, we present a new specimen from the Kimmeridgian of the Solnhofen region. In contrast to a recently described isolated soft body preserving the male reproductive organs, the new specimen for the first time shows a structure, which we interpret as the ovaries of the female containing immature eggs and further organs. These two specimens are of great importance for sexing ammonoids and for estimating fecundity. The high reproductive rate of Jurassic ammonites underlines their great abundance and the important role of juvenile ammonoids at the base of Devonian to Cretaceous food webs.