An order of ray-finned fish, also called the Plectognathi. Sometimes these are classified as a suborder of the Perciformes. Various bizarre forms are included here:
... BC - 2nd century BC
Decades: 290s BC 280s BC 270s BC 260s BC 250s BC - 240s BC - 230s BC 220s BC 210s BC 200s BC 190s BC
Years: 253 BC 252 BC 251 BC 250 BC 249 BC ...