When does the fossil record indicate that fish with jaws first appeared?

Question

When does the fossil record indicate that fish with jaws first appeared?

A. Mesozoic era
B. Cenozoic era
C. Paleozoic era
D. Pre-cambrian time

Answer 1

As Richard R indicated, C is correct.
"Gnathostomes (have jaws). Major evolutionary step ahead: animals can bite! Led to major radiation of the gnathostomes. Most primitive animals-with-jaws: fossil Placodermi. Placoderms are extinct armored fish with jaws, a hinged bony apparatus attached to skull. Large jaws, but no teeth; bony plates associated with jaws functioned as teeth. Silurian-Devonian into Carboniferous; very large (up to 18 ft). Paired pectoral fins ('arms') as well as pelvic fins ('legs'). Very extensive exoskeleton (armor).
Origin of jaws: derived from gill arches, i.e., support for gills, made of cartilage. Several rows of these support structures; anterior (front) pair of these become jaws, pair directly behind become 'suspensorium', means of suspending jaws from skull. Modern fish still have gill arches behind their jaws. Note: function of structure (biting) is new, structure itself (gill arches) not."

Answer 2

Unless my 30 year old geology information has been rendered obsolete the answer is C. More precisely the Devonian. or late Silurian.