| P number: | P549505 |
|---|---|
| Caption: | Bourgueticrinus papilliformis, a fossil crinoid. |
| Description: | Bourgueticrinus papilliformis is a species of the very small crinoid genus, Bourgueticrinus. This genus is found in the late Cretaceous Chalk, which was laid down between about 65 and 98 million years ago and it became extinct in the Eocene times (about 40-50 million years ago). The different species of Bourgueticrinus can be used to correlate parts of the Chalk. Correlation is the process of determining the age equivalence of several geographically separate rock units. Bourgueticrinus is a very small crinoid, which has a cup, or 'calyx' (which is up to 1 cm. across), attached to the end of a short stem. The cup (a-d) is made of 11 plates, although it can be difficult to distinguish these. The flexible stem was made of a number of elongate cylindrical columnals (e). Arms, which extended from the top of the cup, directed food particles towards the moouth. Different species can be recognised by the shape and size of the cup and the plates that form it. Crinoids are an ancient group of animals that first appeared during the Cambrian times, over 500 million years ago, and can still be found living today. The animal lived in a cup-like structure ('calyx') made of numerous calcite plates. It had many arms ('brachials'), which waved in the sea water above the animal to collect food. The calyx of most crinoids is attached to a long flexible stem, made of a stack of calcite plates ('columnals'), that was anchored to the sea bed, sometimes by a holdfast. |
| Photographer: | Unknown |
| Copyright statement: | NERC |
| Orientation: | Portrait |
| Size: | 387.63 KB; 587 x 1000 pixels; 50 x 85 mm (print at 300 DPI); 155 x 265 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
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