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Scientists have discovered direct evidence of the diet of one of the most important group of ammonites, distant relatives of squids, octopuses and cuttlefishes. The discovery may bring a new insight on why they became extinct 65.5 million years ago, at the end of the Cretaceous.
Ammonites are among the world's most well known fossils but until now, there has been no experimental evidence of their place in the food chain. Using synchrotron X-rays, a Franco-American team of scientists led by Isabelle Kruta has discovered exceptionally preserved mouth organs of ammonites, along with the remains of a meal that show that these ammonites dined on plankton. Plankton was largely destroyed in the wake of the same asteroid impact that led to the demise of the dinosaurs and other species. After losing their source of food, ammonites and many other marine groups could not survive this cataclysmic event. The findings are published this week in Science.
Ammonites are extinct relatives of the squid and octopus. The Nautilus, a present-day marine invertebrate, is similar in appearance to many ammonites but is a more distant relative. Ammonites appeared about 400 million years ago (the Early Devonian) and experienced a population explosion in the early Jurassic. In fact, ammonites became such an abundant and diverse part of the marine fauna that they are used by paleontologists as classic "index" fossils to determine the relative ages of marine Mesozoic rocks in which they are found.
The team of researchers, led by Isabelle Kruta (MNHN, CNRS, UPMC), used the ESRF to perform X-ray scans of exceptional quality of Baculites fossils found on AMNH expeditions to the Great Plains in the United States. Results suggests that the large group of ammonites to which Baculites belongs, had jaws and radula (a kind of
|Contact: Claus Habfast|
European Synchrotron Radiation Facility