The half round shield, Hemicyclaspis (1869)

Phylum : Chordata Class : Osteostraci Order : Atelaspidiformes Genus : Hemicyclaspis Species : H. murchisoni

Whencompared to other atelaspidiformes,‭ ‬Hemicyclaspis is considered to have been a better swimmer thanks to the presence of a more developed tail and two forward flaps that acted like pectoral fins,‭ ‬controlling pitch and allowing for level swimming in open water.‭ ‬Despite thee swimming adaptations,‭ ‬the mouth was still on the bottom which means that Hemicyclaspis was probably still a bottom feeder that searched for small organisms and organic matter in the sediment of Silurian oceans.