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P549581

Uploaded on:
17/03/2009 10:22:33
Type:
Digital Asset
File Size:
500.28 KB
Dimensions:
1000 x 651 pixels
4039 views 4 downloads
P number: P549581
Caption: Pholidophorus, a Jurassic fish.
Description: Ray-finned fish inhabited both fresh and marine waters and many different types evolved, including the teleosts a group into which most living fish can be placed. These have thin scales, symmetrical tails and mobile jaws and fins. One of the earliest teleost was Pholidophorus, which lived in the sea during early Jurassic times, about 200 million years ago, and grew to about 40 cm. in length. Pholidophorus was an early teleost and still had heavy enamelled scales and only a partially ossified backbone. It resembles a herring, and although not preserved in the illustrated specimen, had a symmetrical tail, a large dorsal fin half-way down its back and pectoral, pelvic and anal fins on its underside. The large eyes, flexible jaws and small rounded teeth suggest this agile predator fed on crustaceans and smaller fish. 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: Unknown
Orientation: Landscape
Size: 500.28 KB; 1000 x 651 pixels; 85 x 55 mm (print at 300 DPI); 265 x 172 mm (screen at 96 DPI);
Average Rating: Not yet rated
Categories: Best of BGS Images/ Fossils  

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