Orthacanthus (Greek for "vertical spike"); pronounced ORTH-ah-CAN-thuss
Shallow seas of Eurasia and North America
Devonian-Triassic (400-260 million years ago)
Size and Weight:
About 10 feet long and 100 pounds
Long, slender body; sharp spine jutting out from head
For a prehistoric shark that managed to persist for almost 150 million years--from the early Devonian to the middle Permian period--not a whole lot is known about Orthacanthus other than its unique anatomy. This early marine predator had a long, sleek, hydrodynamic body, with a dorsal (top) fin that ran almost the entire length of its back, as well as a strange, vertically oriented spine that jutted out from the back of its head. There's been some speculation that Orthacanthus feasted on large prehistoric amphibians (Eryops being cited as a likely example) as well as fish, but proof for this is somewhat lacking.