Tuesday, 12 January 2016

Scathascolex minor: A Palaeoscolecid Worm from the Middle Cambrian Burgess Shale of British Colombia.

Palaeoscolecids are a group of vermiform animals (worms) known from Cambrian to Silurian deposits. They had rings similar to those of Annelid Worms, but were covered in mineralized sclerites (scales), and had evertable probosces similar to those of  Priapulids. They are considered to have been Ecdysozoans, members of the group that includes Arthropods, Tardigrades, Velvet Worms, Nematodes, Nematomorphs, Kinorynches, Loriceferans and Priapulids, though exactly how they are related to other members of the group is unclear.

In a paper published in the journal Palaeontology on 15 October 2015, Martin Smith of the Department of Earth Sciences at University of Cambridge describes a new species of Palaeoscolecid Worm from the Middle Cambiran Burgess Shale of British Colombia, Canada.

The new species is named Scathascolex minor, where 'Scathascolex' refers to the Dragon Scatha from the writings of JRR Tolkien, and 'minor' refers to the small size of the specimens and the fact that some of the specimens were referred to species 'Ottoia minor'. The species is described from three specimens, though seven specimens are referred to the species. Only one of the specimens is complete, this measures 20 mm in length and is 1.3 mm in width, though the largest specimen is 2.4 mm in width and therefore thought to have been around 40 mm in length.

Scathascolex minor from the mid-Cambrian Burgess Shale. (A) NMNH 83939d, anterior section. (B) NMNH 83939b.1, anterior section. (C) NMNH 196193, medial section. (D) NMNH 202689, anterior section, proboscis perpendicular to plane of fossil. (E) NMNH 203005, posterior section showing evidence of extensive decay. (F) NMNH 83939b.2, medial section. Smith (2015).

The trunk section of Scathascolex minor is covered by bands of scales 75–150 μm across separated by scaleless areas 50-100 μm across. The scaled areas each have about 100-200 disk-shaped scales which are about 15-20 μm in diameter, Smith suggests that these may have bee used to gain traction during movement. though it is unclear if the living worms lived within the sediment or on its surface.

See also...

http://sciencythoughts.blogspot.co.uk/2015/12/eokinorhynchus-rarus-kinorhynch-from.htmlEokinorhynchus rarus: A Kinorhynch from the Early Cambrian of Sichuan Province, China.                                                 Kinorhynches are tiny (at most 3 mm) worm like animals found in marine sediments, with segmented tube- or barrel-shaped bodies, separate head and neck regions and evertable pharynxes. They are related...
http://sciencythoughts.blogspot.co.uk/2015/06/quisarctus-yasumurai-new-species-of.htmlQuisarctus yasumurai: A new species of Tardigrade from a submarine cave in the Okinawa Islands.                                                  Tardigrades, or Water Bears, are minute (generally less than 1 mm and always less than 3 mm) aquatic animals related to Arthropods, Nematodes...
http://sciencythoughts.blogspot.co.uk/2015/05/priapulid-worms-from-middle-cambrian-of.htmlPriapulid Worms from the Middle Cambrian of Canada.                                                Priapulid Worms are a form of marine worms with denticle-covered pharynxes which can be everted to form proboscises. They are a minor element of..
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