Tentaculites Explained

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 both as calcitic shells with a brachiopod-like microstructure^[1] and carbonaceous 'linings'.^{[2] [3]} The "tentaculites" (i.e. tentaculita) are also referred to as the styliolinids.

Affinity

The taxonomic classification of tentaculitids is uncertain. Some grouped them with pteropods, but there is no modern support and only superficial similarity.^[4] They may also be related to other conical shells of uncertain affinity including cornulitids, Anticalyptraea, microconchids and trypanoporids.^[5] Their shell microstructure has warranted their comparison with the brachiopods and phoronids,^[6] and the possible Ediacaran lophophorate Namacalathus.^[7]

Morphology

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.

Ecology

Some species are inferred to have been planktonic.^[8]

See also

• Mari Mari Group, fossil formation in the state of Amazonas of northwestern Brazil

Further reading

• Treatise on Invertebrate Paleontology, Part W - Miscellanea. Geological Society of America and University of Kansas Press, 1962. LCCN 53012913

Notes and References

1. Towe . K. M. . Tentaculites: Evidence for a Brachiopod Affinity? . Science . 201 . 4356 . 626–628 . 1978 . 17794124 . 10.1126/science.201.4356.626. 1978Sci...201..626T . 22806221 .
2. 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.
3. Filipiak . P. . Jarzynka . A. . Organic Remains of Tentaculitids: New Evidence from Upper Devonian of Poland . Acta Palaeontologica Polonica . 54 . 111–116 . 2009 . 10.4202/app.2009.0111. free .
4. Ager, 1963, Principles of Palaeontology
5. Vinn, O. . Adaptive strategies in the evolution of encrusting tentaculitoid tubeworms . Palaeogeography, Palaeoclimatology, Palaeoecology . 2010 . 292 . 1–2 . 211–221 . 2014-01-11 . 10.1016/j.palaeo.2010.03.046. 2010PPP...292..211V .
6. 10.1080/11035897.2012.669788 . Phenetic phylogenetics of tentaculitoids — extinct problematic calcareous tube-forming organisms . 2012 . Vinn, O. . Zatoń, M. . GFF . 134 . 2 . 145–156 . 83591938 . 2014-06-11.
7. 1. Zhuravlev, A.Y., Wood, R.A., and Penny, A.M. (2015). Ediacaran skeletal metazoan interpreted as a lophophorate. Proc. R. Soc. B 282, 20151860. Available at: http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2015.1860.
8. LARSSON K. . 1979 . Silurian tentaculitids from Gotland and Scania. Fossils and Strata . 11 . 180.