Fresh fossil evidence of eye forerunner uncovered

December 12, 2007

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. His findings are published in the latest edition of Biology Letters, a journal of the Royal Society, London.

“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.

“These extinct placoderms had the eyeball still connected to the braincase by cartilage, as in modern sharks, and a primitive eye muscle arrangement as in living jawless fish.” Dr Young said that this anatomical arrangement is different from all modern vertebrates, in which there is a consistent pattern of tiny muscles for rotating each eyeball.

The placoderm fossils were analysed using computer X-ray tomography at ANU, a scanning technique that creates a three-dimensional image of complex organic structures. “What this research shows is that 400 million years ago there was already a complex eye, and one that was an intermediate form between jawless and jawed vertebrates,” Dr Young says. “This means that we’re able to add one more piece to the puzzle of how the human eye came to be.”

Source: Australian National University

Explore further: Fossil fish offers clues to jawed vertebrates origins

Related Stories

Fossil fish offers clues to jawed vertebrates origins

February 12, 2014

A team of French and Swedish researchers have presented new fossil evidence for the origin of one of the most important and emotionally significant parts of our anatomy: the face. Using micron resolution X-ray imaging, they ...

Discovery sheds light on how vertebrates see

August 2, 2016

New research led by the University of Leicester has overturned a long-standing theory on how vertebrates evolved their eyes by identifying remarkable details of the retina in the eyes of 300 million year-old lamprey and hagfish ...

Recommended for you

Evaluation of scientific rigor in animal research

December 2, 2016

The "reproducibility crisis" in biomedical research has led to questions about the scientific rigor in animal research, and thus the ethical justification of animal experiments. In research publishing in the Open Access journals ...

Researchers find evidence of original 1620 Plymouth settlement

November 30, 2016

Three hundred and ninety-five years after Pilgrims celebrated the first Thanksgiving in Plymouth, Massachusetts, researchers from UMass Boston's Andrew Fiske Memorial Center for Archaeological Research can say they have definitively ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.