Saturday 3 September 2016

Palaeoconchus wilsoni: A new species of Microconchid from the Silurian of Estonia and Gotland.

Microconchids are a groups of poorly understood encrusting organisms known from the Ordivician to the Jurassic. They formed tubular encrustations on hard substrates in a similar way to modern Serpulid Worms, and were for a long tme were thought to be early members of that group, but the tubes have since been recognised as being structurally different to those made by Serpulids, leaving the identity of the tube-mekers enigmatic.

In a paper published in the Estonian Journal of Earth Sciences on 20 June 2016, Michał Zatoń of the Faculty of Earth Sciences at the University of Silesia, Olev Vinn of the Department of Geology at the University of Tartu and Ursula Toom of the Institute of Geology at the Tallinn University of Technology describe a new species of Microconchid from the Silurian of Estonia and Gotland.

The new species is placed in the genus Palaeoconchus, and given the specific name wilsoni, in honour of Mark Wilson of the College of Wooster in Ohio, for his work on the biotas of hard substrates, including Microconchids. It is described from six specimens; five from the Kuressaare Formation of Saaremaa Island, Estonia, where they were found growing on Rugose Corals, and one from Gotland in Sweden, where it was encrusting a Brachiopod Shell. A number of other specimens were collected on Saaremaa Island, but no others found in Sweden.

Palaeoconchus wilsoni, from Saaremaa Island, Estonia (A–E) and Gotland, Sweden (F). Scale bars 500 μm. Zatoń et al. (2016).

The specimens are flattened and dextrally coiled (coiling to the right when seen from above, clockwise) and ornamented with thicj transverse ribs. The largest specimens reach 2.7 mm.

Encrusted Rugose Corals from Saaremaa Island, Estonia. (A) Auloporids (white arrow), Cornulitid Conchicolites (black arrow) and two associated Microconchids. (B) Anticalyptraea (white arrows) and Trepostome Bryozoan colony (black arrow). (C) Ascodictyids (black arrows) and associated Microconchids. (D) Cornulitid Conchicolites (black arrows). (E) Rugose spatfalls within the calyx (black arrow) and a Hederelloid colony (white arrow). Zatoń et al. (2016).

See also... conollyi: A new species of Marrellomorph Arthropod from the Middle Ordovician of Pembrokeshire, Wales.         The Marrellomorphs are a poorly understood group of early Arthropods known from Palaeozoic deposits at a number of sites around the world. They are not thought to have had any mineralized parts, making them rare in the fossil record, and to date only three species... Annelid Worm tubes from the Early Devonian of Brazil.                                   Worm tubes first appear in the fossil record in the Ediacaran and become increasingly common through the Palaeozoic. Most Worm tubes today are made by Polychaete Annelids, a group which have existed... Iocrinus africanus: A new species of Crinoid from the Middle Ordovician of Morocco.   The Ordovician was a period of rapid diversification and geographic expansion in many Echinoderm groups, including Crinoids. However their fossil record is not good in every area, making understanding this period in their evolutionary history difficult. The northern Gondwanan continental shelf was an important area...
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