Stephanoceras humphreysianum an ammonite belonging to the Bajocian (170-168 Ma, Middle Jurassic).
This 45 cm and 13 cm wide fossil cephalopod is our piece of the mont of December and, therefore, the last piece of the month of the year 2022. It was found at the La Cantera de la Pedrera site in the town of Ribarroja del Túria, which is listed as a Place of Geological Interest (LGI).
This species is the type species of its genus, Stephanoceras. A type species is defined as one whose morphology is used to describe taxonomically the other species of the genus. It is characterized by presenting an evolute Shell with well-developed veins and tubercles. The ribs sometimes bifurcate (ore ven trifurcate) at the outer edge of the carapace. The spieces was described as Ammonites humphriesianum by malacology (mollusc shell) expert James DeCale Sowerby in 1825 and was later renamed by Sydney Buckman in 1898.
