Tentaculites is an extinct genus of conical fossils of uncertain affinity, class Tentaculita, although it is not the only member of the class. It is known from Lower Ordovician to Upper Devonian deposits[1] both as calcitic shells with a brachiopod-like microstructure[2] and carbonaceous 'linings'.[3][4] The "tentaculites" (i.e. tentaculita) are also referred to as the styliolinids.
The taxonomic classification of tentaculitids is uncertain. Some grouped them with pteropods, but there is no modern support and only superficial similarity.[who?][5] They may also be related to other conical shells of uncertain affinity including cornulitids, Anticalyptraea, microconchids and trypanoporids.[6]
Their shell microstructure has warranted their comparison with the brachiopods and phoronids,[2][7]
and the possible Ediacaran lophophorate Namacalathus.[8]
Morphology
Sketch of a Tentaculites ornatus, Silurian.Tentaculitid from the New Creek Limestone (Lochkovian, Early Devonian) of New Creek, West Virginia.
Tentaculitids have ribbed, cone-shaped shells which range in length from 5 to 20 mm. Some species septate; their embryonic shell, which is retained, forms a small, sometimes spherical, chamber.[4]
Ecology
Some species are inferred to have been planktonic.[9]
^Wood, G.D., Miller, M.A., and Bergstrom, S.M. 2004. Late Devonian (Frasnian) tentaculite organic remains in palynological preparations, Radom−Lublin region, Poland. Memoirs of the Association of Australian Palaeontologists 29: 253–258.
