Durotrigensia is a genus large to giant ammonites (Ammonitida

Ammonitida

The Ammonitida is an order of more highly evolved ammonoid cephalopods from the Jurassic and Cretaceous time periods, commonly with intricate ammonitic sutures....

) in the perisphinctoid family Parkinsoiniidae with sharply and finely ribbed inner whorls, smooth outer whorl, and without tubercles or lappets that lived during the Bajocian

Bajocian

In the geologic timescale, the Bajocian is an age or stage in the Middle Jurassic. It lasted from approximately 171.6 Ma to around 167.7 Ma . The Bajocian age succeeds the Aalenian age and precedes the Bathonian age....

 stage of the Middle Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 some 170 to 164 million years ago.

Durotrigensia is sometimes considered a subgenus of Parkinsonia and is related also to Oraniceras and Okribites

Okribites

Okribites is an extinct genus from a well-known class of fossil cephalopods, the ammonites. It lived during the Jurassic Period, which lasted from approximately 200 to 145 million years ago....

.