When did ammonites go extinct
Ammonite Quotes (2 quotes)
A team of international researchers led by scientists from the American Museum of Natural History New York , have been trying to unravel one of the great mysteries of invertebrate palaeontology. Why did the Ammonites go extinct but their relative the Nautilus survive the Cretaceous extinction event? Neil Landman believes that over specialisation and limited geographic distribution led to the downfall of this particular group of chambered shelled molluscs. A Nautilus Compared to an Extinct Ammonite. Ammonites belong to the Class Cephalopoda and they seem to have been entirely marine, pelagic animals living above the sea floor.
Unravelling an Ammonite Mystery
All rights reserved. Ammonites were predatory, squidlike creatures that lived inside coil-shaped shells. Like other cephalopods, ammonites had sharp, beaklike jaws inside a ring of tentacles that extended from their shells to snare prey such as small fish and crustaceans. Some ammonites grew more than three feet one meter across—possible snack food for the giant mosasaur Tylosaurus. Ammonites constantly built new shell as they grew, but only lived in the outer chamber. They scooted through the warm, shallow seas by squirting jets of water from their bodies.
By Michael Marshall. If so, their demise may have opened up the seas to modern plankton-feeders like the huge baleen whales. Ammonites resembled squid, but with shells coiled in spirals like the horns of a ram. They appeared million years ago and survived over million years, until they were wiped out at the same time as the dinosaurs. Although they were extremely common, their diet has eluded us because the normal methods of studying fossils destroy the fine detail of their jaws. Isabelle Kruta of the National Museum of Natural History in Paris, France, and colleagues set out to change that using an imaging technique called synchrotron X-ray microtomography.