"pearls" in ammonites A recent study of peculiar pearl-like structures in fossil ammonites (cephalopods) by Dr. Dieter grain from the Museum of Natural History, and Kenneth De Baets and Dr. Chris Klug of the Paleontological Museum and Institute of University of Zurich allows insight into a complex case of geologically very early coevolution.
new fossil material shows that certain deposits on the inside the shells used ammonoids (extinct group of shelled cephalopods) have been triggered by parasites. This new finding provides an age of about 400 million years ago (Devon) one of the earliest evidence of coevolution between host and parasite dar. parasitologists are normally limited to comparisons between DNA-based phylogenetic trees need of host and parasite, for information about their co-evolution of obtained. The pathologies of the Devonian ammonoids are very similar to those that are raised in Recent shells through intermediate stages of trematodes (Trematoda). These similarities suggest that the trematodes, which are now next to molluscs and vertebrates and occasionally infect humans, there is already nearly half a billion years, and at that time developed a complex life cycle. The last hosts in the life cycle of these parasites were probably early vertebrates (fish). The parasites accompanied the ammonoids over a period of about 15 million years ago. Thereafter, the ammonoids were apparently has developed resistance to these parasites, at least there are no longer the pearl-like marks on younger ammonoids packages.
publication of the article:
De Baets, K., Klug, C. & Korn, D. (2011): Devonian ammonoid-pearls and parasites co-evolution. - Acta Palaeontologica Polonica 56 (1), 2011: 159-180 doi:10.4202/app.2010.0044
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