Xiphactinus audax, the X fish skull Stegosaurus The large hollow bony crest

The large hollow bony crest had not yet developed on this young and small specimen

Scientific Name: Phacops africanas

17--Isolelus gigas--Ordovician--Trenton Group

Megaraptor was initially described as a giant dromaeosaur (the "raptors")

Xiphactinus audax, the X fish skull Stegosaurus The large hollow bony crestXiphactinus audax (from Latin and Greek for "audacious sword ray") was a large, 15 to 20 foot long predatory bony fish that lived in the Niobraran Sea, in what is now North America, during the Late Cretaceous. When alive, the beast would have resembled a gargantuan, fanged tarpon. Skeletal remains of Xiphactinus have come from Kansas, Alabama, and Georgia. Despite being preyed on by sharks and mosasaurs, X. audax was, nonetheless, a voracious predator