Stratigraphy
Parkinsonia parkinsoni, an ammonite zone fossil.
Parkinsonia parkinsoni is a zone fossil of the Late Bajocian, Middle Jurassic. used to identify and date the rock layer in which they are found, and to correlate strata world-wide.
Parkinsonia parkinsoni fossils are approximately 168 million years old dating back to the Late Bajocian (Middle Jurassic). Parkinsonia parkinsoni fossils are commonly found in the Upper Inferior Oolite Series of Britain.
Zone fossil
A fossil which is characteristic of a particular period in geological time and has precise distribution within the rock record. Zone fossils can be used to identify and date the rock layer in which they are found, and to correlate strata world-wide.