| P number: | P549459 |
|---|---|
| Caption: | Limnoptera, a fossil bivalve. |
| Description: | Limnoptera is a distant relative of Pecten, but one that was fixed to the substrate by a bundle of hair-like strands (a byssus) that protruded from a notch in one valve. It evolved during late Silurian times and became extinct in mid-Devonian times (about 420 to 380 million years ago). Limnoptera is broadly triangular in shape, although it has a very large and elongate wing-like projection. The surface of each valve is covered in radial ridges which also extend onto the wing. Growth lines are arranged concentrically around the valve. The shell of the illustrated specimen appears to have been damaged and repaired during its life as there is an interruption of the ornament and growth lines on the lower part of the valve. Bivalves are molluscs that first evolved over 500 million years ago during the middle of the Cambrian period. They flourished during the Mesozoic (particularly the Jurassic and Cretaceous) and in the Cainozoic eras. They are abundant in the modern seas and dead shells are often found in the beach sands around the world. The early bivalves are associated with marine palaeoenvironments, but they later colonised brackish and fresh waters. As they are so common in modern times, their mode of life can be extrapolated back into the geological past and used in palaeoenvironmental reconstructions. |
| Photographer: | Unknown |
| Copyright statement: | NERC |
| Orientation: | Portrait |
| Size: | 690.41 KB; 973 x 1000 pixels; 82 x 85 mm (print at 300 DPI); 257 x 265 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
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