File:Ichthyosaur coprolites.jpg

English: Ichthyosaur coprolites from the Jurassic of England.

Biogenic products are objects produced by ancient organisms. Many paleontologists refer to these as trace fossils, but they really aren't. Examples of fossil biogenic products include eggs, amber (fossilized tree sap), coprolites (fossilized feces), and spider silk.

Coprolites are fossilized fecal masses. They range in size from microscopic-sized pellets to moderately sizable dung piles. The most famous attributed examples are “Washington coprolites” from the Miocene Wilkes Formation of Washington State, USA. But these are now considered cololites (intestinal casts). True coprolites are fossilized dung. Thin sections of coprolites often reveal fragments of incompletely digested plant matter or sometimes undigested animal tissue. So, coprolite studies can provide information about the diet of ancient organisms, assuming the coprolite maker is known with some specificity (which is often not the case).

These coprolites have been attributed to ichthyosaurs. Ichthyosaurs are an extinct group of large, predatory, marine reptiles. They had a fusiform body similar in gross morphology to modern dolphins and porpoises. The latter are mammals, while ichthyosaurs were reptiles. The evolution of similar body plans by unrelated organisms is called convergent evolution. Ichthyosaurs and dolphins are the most commonly cited examples of this evolutionary process.

Ichthyosaur fossils are only found in Mesozoic sedimentary rocks - they first appear in the Triassic and go extinct in the Cretaceous.

Classification: Animalia, Chordata, Vertebrata, Reptilia, Ichthyosauria

Stratigraphy & locality: unrecorded/undisclosed

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See info. at:

en.wikipedia.org/wiki/Ichthyosaur