1 of 9

Write now Article Tools

In September 2003, Randall Miller, a paleontologist from the New Brunswick Museum, found the oldest intact shark fossil ever, taking us back 410 million years. This example of Doliodus problematicus is only 9 inches long but shares the essential shark characteristics we know and love such as bony jaws, teeth which just keep on growing back in, and a skeleton made not of bone, but of cartilage.

The jury is out on the exact connections involved, but the New Brunswick fossil is an example of one of the earliest, most primitive of sharks.

410 millions years ago we were well into what is often called the 'Age of the Fish'. This was the Devonian Period which falls roughly between 418 and 360 million years ago. This is long before mammals, at least 150 million years before the first dinosaurs. The land formed only two masses, Laurasia and Gondwanaland. The seas spread out over great shelves, forming the relatively warm, shallow areas that really give life rocket fuel. The oceans were heaving and the early sharks were did well for themselves.

Sharks have had a chequered history, sometimes burgeoning and diverse, at others, after cataclysmic events, down to a handful of species. This change in fortunes has happened 5 times since our Doliodus was around. The incredible variations they have displayed over the millenia are witness to the elegance and adaptive power of their basic construction.

Most of what we know about sharks has been learned from shark teeth. These have come down to us in abundance, being the hardest structures in a sharks body. Palaeontologists, by studying the teeth of live sharks, have learned to read the fossils so that they can tell the difference between inter and intraspecies variations.

Doliodus' immediate ancestors are referred to as 'jawed fish', dating from the late Ordovician to the early Silurian, around 455-450 million years ago. Until recently it was thought that Leonodus, who appears in the fossil record about 400 million years ago, was probably the first true shark, but of course our little guy calls this into question. Around the same time as Leonodus we had the first Cladoselache who, although he had some variations (such as a mouth on the front of his head instead of his jaw being being 'underslung'), was the earliest species that could definitely be identified as a shark. He, however, has not presented us with an articulate fossil.

Burgeoning life also meant fierce competition. These little sharks weren't

• 1
• 2
• 3
• next page >>

Add your voice

Know something about The evolution of sharks?
We want to hear your view. Write now!