Uploaded on:
17/03/2009 09:54:49
Digital Asset
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348.57 KB
1000 x 625 pixels
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P number: P549493
Caption: Devonian fish.
Description: Many different types of jawless fish lived during the Devonian times, about 354 to 417 million years ago, including Cephalaspis (middle). Jawed fish were mainly 'armoured' types, such as Coccosteus (top) and Groenlandaspis (bottom). Cephalaspis had a large, bony head shield and probably spent its time feeding on the muddy sea floor. Coccosteus was a fast-swimming carnivore. It had a heavily armoured, but hinged, head shield, a body that lacked scales and a powerful tail. Groenlandaspis also had a hinged head shield that allowed it to open its jaws wide. This flattened bottom dweller probably ate molluscs and crustaceans. Fish are cold-blooded vertebrates with a braincase, fins for swimming and gills to take oxygen from the water (although some also have lungs). They therefore differ from other aquatic creatures like invertebrate molluscs or crabs; amphibians and reptiles, which have lungs and limbs rather than gills and fins; and whales and dolphins which are warm-blooded mammals. Fish are the first vertebrates, having evolved during the early Cambrian over 500 million years ago.
Photographer: Unknown
Copyright statement: NERC
Orientation: Landscape
Size: 348.57 KB; 1000 x 625 pixels; 85 x 53 mm (print at 300 DPI); 265 x 165 mm (screen at 96 DPI);
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