This is based on the knowledge that some modern fishes such as coelacanths and sharks have spiral-shaped intestines. It is difficult to find out exactly what animal produced a now-coprolite, however, ...

Fossils found in the northern part of Hokkaido are a new type of ammonite, the once-ubiquitous spiral-shelled creatures that went extinct with the dinosaurs 65 million years ago, researchers said.