ARTURIA OF THE PACIFIC

This lovely Lower Miocene nautiloid is Aturia angustata collected on the foreshore near Clallam Bay, Olympic Peninsula, northwestern Washington. 

I have been exploring Washington State for many years. It is rugged, windswept and has amazing fossil exposures all along its northern edge. The area goes by the name of the Olympic Peninsula and it is a wilderness playground. The sites I usually visit are Majestic Beach for its rare but prized fossil whale bone.

Further west are the beach exposures that have fossil echinoids in matrix and Ghost shrimp claws in concretion. There is a clay mine that holds wonderful nautiloids like the creamy Aturia you see here. Sometimes they are cemented together and come out whole. Sometimes calcified and show yellow, brown and white when you hold them to the light. Further up are the beach exposures along Clallam Bay.

Aturia is an extinct genus of Paleocene to Miocene nautilids within Aturiidae, a monotypic family, established by Campman in 1857 for Aturia Bronn, 1838, and is included in the superfamily Nautilaceae in Kümmel, 1964.

Aturia is characterized by a smooth, highly involute, discoidal shell with a complex suture and subdorsal siphuncle. 

Their shells are rounded ventrally and flattened laterally; the dorsum is deeply impressed. The suture is one of the most complex within Nautiloidea. It has a broad flattened ventral saddle, narrow pointed lateral lobes, broad rounded lateral saddles, broad lobes on the dorso-umbilical slopes, and a broad dorsal saddle divided by a deep, narrow median lobe. 

The siphuncle is moderate in size and located subdorsally in the adapical dorsal flexure of the septum. Based on the feeding and hunting behaviours of living nautiluses, Aturia most likely preyed upon small fish and crustaceans. It is well worth exploring the exposures at Clallam Bay. The local clay quarry is on private land so you would need to seek permission. I have also seen calcified beauties of this species collected from river sites within the Olympic Peninsula range, though I have not explored these myself.