Tricarinidae

Tricarina is a genus of decapod crustaceans, known from a single incomplete fossil specimen from the Cretaceous of western Iran. It has a flattened body with three longitudinal ridges, which give it its name.

The single known specimen of Tricarina was discovered in a well core that had been bored at a site on the Khuzestan Plain in south-western Iran, at 31°18′13.3″N 47°47′28.6″E / 31.303694°N 47.791278°E / 31.303694; 47.791278, and at a depth of 3,852 metres (12,638 ft). The rocks that contain it are calcareous shales, which form part of the Gadvan Formation, and are part of the main sequence of rocks for the production oil and gas around the Persian Gulf. Examination of the foraminiferan fossils show that the shales are Barremian to Aptian in age.

The fossil of Tricarina gadvanensis is known from a part and counterpart from a core drilled to make an oil well. It has been deposited in the Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, as specimen number CM 54197. A segment of the cylindrical core was cut away before the fossil was discovered, and the fossil is accordingly incomplete: the front of the carapace extends over the cut edge, and much of the pleon is outside the edge of the core. Most of the carapace is visible, and shows a flattened form, with three distinct longitudinal or ridges. The bases of the antennae are preserved, but no eyes are apparent. A single pereiopod (walking leg) is visible, and it ends without a chela (claw).