National Geographic News
Add another name to the tide of Canadian rock stars.
Paleontologists announced today they've unearthed the world's oldest, intact shark fossila 409-million-year-old specimen of a small, primitive species known as Doliodus problematicusfrom a site in New Brunswick, Canada.
The fossil, which measures 23 centimeters (9 inches) long from its snout to upper trunk, includes the fish's braincase, scales, calcified cartilage, large fin spines, and a battery of scissor-like teeth preserved in the upper and lower jaw. Researchers estimate the species only grew 50 to 75 centimeters (20 to 30 inches) long, about the size of a large lake trout.
Randall Miller, a paleontologist at the New Brunswick Museum in Saint John, led the field expedition that found the fossil. He said he hoped merely to collect a few more teeth of Doliodus, a species known to science for over a century. Only later did he learn that his team found the first complete specimen of the ancient sharkand the world's oldest intact shark fossil.
Miller collaborated with Richard Cloutier, a paleontologist at the University of Quebec at Rimouski, and Susan Turner, a world expert on fossil shark teeth at the Queensland Museum in Australia, to describe the fossil. Their paper appears tomorrow in the science journal Nature.
The New Brunswick fossil predates other fossil sharks from Antarctica and South Africa, previously known as the world's oldest, by 15 million years.
Paleontologists say the fossil will help shed light on the early evolution of primitive sharks and other vertebrate, or backboned, fish from the Devonian Period, the era between 418 million and 360 million years ago often referred to as the age of fish when most life on Earth was confined to the world's oceans.
"Quite a few paleontologists or ichtyologists [fish biologists] have been trying to imagine what the oldest shark looked like. This [fossil] is giving us the information," said Cloutier.
Miller and Turner speculate the shark may have resembled an angel shark, a ray-like bottom-dweller found in most temperate and tropical oceans.
Intact fossils of sharks, a boneless fish, are exceptionally rare. Many ancient shark species are known only by fossil teeth or skin scales. Until the recent find, Doliodus problematicus (Latin for "a problematic deceiver"), was among them.
Researchers discovered the articulated New Brunswick fossil in situ, meaning all its parts, such as the braincase, jaws, teeth, and pectoral fins were found attached in their correct anatomical position. The find will help paleontologists make sense of other isolated, smaller ancient fossil shark specimens.
SOURCES AND RELATED WEB SITES