Wikipedia
Durotrigensia
Durotrigensia is a genus of ammonites ( Ammonitida) in the perisphinctoid family Parkinsoniidae.
Durotrigensia is sometimes considered a subgenus of Parkinsonia and is related also to Oraniceras and Okribites.
These cephalopods lived during the Bajocian stage of the Middle Jurassic some 170 to 164 million years ago.