Amblysemius bellicianus

Amblysemius bellicianus Thiollière 1852

Upper Jurassic

Tithonian (Malm zeta)

Zandt

Germany

Amblysemius bellicianus was clearly a predator as evidenced by its mouth full of sharp teeth. It was a notable fast swimmer. Together with its only sister genus Caturus, Amblysemius was a member of the extinct Halecomorpha family Caturidae.

Once being a diverse major group of bony fishes, the Halecomorpha have only one surviving member, the bowfin (Amia calva) of eastern North America. Living bowfins are remarkably hardy since they have a swim bladder that opens into their esophagus so they can gulp air, and hence survive in water with low oxygen.

Amblysemius was a primitive species of fish that thrived during the Jurassic Period but went extinct by the Lower Cretaceous Period. Amblysemius possessed ganoid scales that are more cycloid in nature and as a member of the holosteans a bony skeleton with a partially ossified vertebral column.

Compared to Caturus, Amblysemius is characterized by its more slender body outline, the bigger and more deeply forked caudal fin being heterocerc with the upper lobe clearly longer than the lower one and the strong dentition. Amblysemius has considerably smaller scales compared to Caturus. Maximum length is around 50cm.