Toothy Ammonites dined on plankton

[Brian.Pearson]

"I was astonished when I saw the teeth for the first time, and when I found the tiny plankton in the mouth," says first author Isabelle Kruta of the Département Histoire de la Terre, Muséum National d'Histoire Naturelle in Paris, France. Kruta began the project as an Annette Kade fellow at the American Museum of Natural History. "For the first time we could observe these delicate, exceptionally well-preserved structures and obtain information on the ecology of these enigmatic animals."

[GregW]

Why did they need to chew anything that small?