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Uploaded on:
17/03/2009 09:53:43
Digital Asset
File Size:
432.53 KB
1000 x 804 pixels
3837 views 6 downloads
P number: P549489
Caption: Jurassic fish.
Description: By the Jurassic, between 142 and 206 million years ago, two large groups of fish dominated the seas and fresh waters. These were the ray-finned fish, including Pholidophorus (top) and Lepidotes (middle), which show many similarities to modern types, and the cartilaginous fish like sharks and the ray Spathobatis (bottom). Pholidophorus was a herring-like fish which resembled modern fish in many ways, although its body was covered with heavy scales and its backbone was less bony compared to modern fish. It was a successful predator with large eyes, flexible jaws and small teeth. Lepidotes was amongst a number of fish that had evolved a shortened upper jaw that was separated from the cheek bones so that the mouth formed a tube into which prey could be sucked. Spathobatis is the earliest of the rays. It had a flattened body and the skeleton was made of cartilage rather than bone. It lived on the sea floor where it fed on shellfish. 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: 432.53 KB; 1000 x 804 pixels; 85 x 68 mm (print at 300 DPI); 265 x 213 mm (screen at 96 DPI);
Average Rating: Not yet rated
Categories: Best of BGS Images/ Artworks  


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