ScienceDaily (Jan. 2, 2008) — Ancient armoured fish fossils from Australia present some of the first definite fossil evidence of a forerunner to the human eye, a scientist from The Australian National University says.
Dr Gavin Young from the Department of Earth and Marine Sciences at ANU has analysed fossilised remains of 400-million-year-old Devonian placoderms – jawed ancestors of modern fish whose bodies were protected by thick bony armour.
“The ancient limestone reefs exposed around Lake Burrinjuck in New South Wales have produced exceptionally well preserved placoderm specimens with the braincase intact,” Dr Young said.
The palaeobiologist discovered that unlike all living vertebrate animals – which includes everything from the jawless lamprey fish to humans – placoderms had a different arrangement of muscles and nerves supporting the eyeball – evidence of an “intermediate stage” between the evolution of jawless and jawed vertebrates.
“The vertebrate eye is the best example of structural perfection – as used by proponents of intelligent design to claim that something so complex couldn’t possibly have evolved,” Dr Young said.
“Part of the trouble in tracing the evolution of the eye is that soft tissues don’t tend to fossilise. But the eye cavities in the braincase of these 400 million-year-old fossil fish were lined with a delicate layer of very thin bone. All the details of the nerve canals and muscle insertions inside the eye socket are preserved – the first definite fossil evidence demonstrating an intermediate stage in the evolution of our most complex sensory organ.
http://www.sciencedaily.com/releases/2008/01/080101193317.htmScan of placoderm eye casing. The arrangement of muscles and nerves supporting the eyeball in placoderms provides evidence of an "intermediate stage" between the evolution of jawless and jawed vertebrates. (Credit: Image courtesy of Australian National University)