Plumulites

Plumulites is normally small animal, for example complete specimen of P. canadensis reached only , and P. bengtsoni being . However, several largest specimens probably reached around , making Plumulites largest machaeridians ever known. Fossils of Plumulites were mostly known from isolated sclerites, and originally considered as arthropod or an echinoderm. However, complete sclerite assemblages of P. richorum described in 1979 has shown that this animal is more likely to be annelid worm, the group which includes modern-day earthworm, leech and bristleworm. According to complete specimens, this animal is surrounded by pairs of outer and interior shell plates. Some of anterior outer and interior shell plates different in shape. Specimen of P. bengtsoni shows soft tissue including parapodia and chaetae. == Taxonomy ==

Preservation of jaw element of P. bengtsoni leads conclusion that machaeridians should be placed within the crown group of Phyllodocida. Species As of 1929, more than 20 species have been described. Subsequent studies have described many more species. • P. canadensis Woodward, 1889 (type) Ottawa, Canada, Katian (Upper Ordovician) • P. bengtsoni Vinther, Van Roy & Briggs, 2008 Fezouata Formation, Morocco, Upper Tremadocian (Lower Ordovician) • P. bohemicus Barrande, 1868 Bohemia, Czech Republic, Lower Ordovician • "P". clarki Shaw, 1966 (=?P. mobergi Clark, 1924) Highgate Formation, Vermont, USA, Lower Ordovician • P. compar Barrande, 1872 Bohemia, Czech Republic, Lower Ordovician • P. folliculum Barrande, 1868 Bohemia, Czech Republic, Lower Ordovician • P. kutscheri Schrank, 1978 Germany, Upper Wenlock Epoch (Silurian) • P. llanvirnensis Withers & Henry, 1926 Pembrokeshire, Wales, United Kingdom, Skiddavian (Lower Ordovician) • P. ruskini Lamont, 1978 Wether Law Linn Formation, Pentland Hills, Scotland, Telychian (Silurian) • P. scoticus R. Etheridge, 1878 Balclatchie group, Ayrshire, Scotland, Caradocian (Upper Ordovician) • P. törnquisti Moberg, 1914 Dalarna, Sweden, Middle Ordovician • P. trentonensis Withers & Henry, 1926 Middle Trenton Beds, New York, USA, Middle Ordovician • P. yeringiae Chapman, 1910 Victoria, Australia, Yeringian (Silurian) ==References==