Plumulites Bengtsoni Machaeridian Armored Worm Fossil (very Very Rare)
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Plumulites Bengtsoni Machaeridian Armored Worm Fossil (very Very Rare):
OKJUSTHOW RARE & MYSTERIOUS??
1. was EXTREMELY lucky to acquire this specimen. It is from the Lower Ordovician and found in the Lower Fezouata Formation in Fezouata Lagerstatten, Morocco. It measures about 39 mm by 18 mm. Meant for only the advanced discriminating collector!
From Reference 3:
Articulated plumulitid machaeridians are rarely preserved intact. Here, we describe a complete specimen of Plumulites canadensis (Woodward, 1889) retaining much of the head region. The two anteriormost pairs of shell plates are quite distinct from the rest in outline, density of concentric rugae, and especially the radial ornamentation of the second pair. We demonstrate that the latter condition is present in other complete plumulitids and therefore widespread, which elucidates a larger diversity in morphology of plumulitids than realized previously.
Machaeridians comprise a group of generally little-known skeletal marine fossils ranging from Ordovician to Permian in age. Until recently, their phylum-level affinities remained controversial, but the discovery of a plumulitid machaeridian with soft parts from the Early Ordovician (Tremadocian) of Morocco (Vinther etal. 2008) showed that these organisms were armoured annelid worms. The monophyly of the Machaeridia (Withers, 1926) is well established on the basis of shared morphological characters associated with a calcitic skeleton made up fundamentally of four posteriorly overlapping longitudinal rows of shell plates, distinguishable into inner and outer sets, ornamented by prominent concentric rugae. The three machaeridian families – Plumulitidae (Jell, 1979), Turrilepadidae (Clarke, 1896) and Lepidocoleidae (Clarke, 1896) – are defined by intergrading variations on this morphological groundplan. Most lepidocoleids, for example, have lost the outer shell plates, likely as a consequence of evolving a more efficient burrowing capability (Vinther and Briggs 2009), but others, like Lepidocoleus ketleyanus ((Reed, 1901) ex Salter 1873), retained the primitive complement of four rows (Bengtson 1977; Dzik 1986; Högström 1997).