[Annelida] RE: Burgess Shale site
(by Geoffrey.Read from niwa.co.nz)
Wed Dec 14 21:10:27 EST 2011
" Which of Walcott's fossil taxa are close to annelid clade, and which are not? You tell me. "
Nothing? Well okay, I'll go through them.
Most of Walcott's (1911) worm taxa have been reinterpreted as not annelids. However, his (then) Canadia seem mostly annelids. Canadia spinosa (with synonyms erected by Walcott) remains as a stem group polychaete, as does Canadia dubia, now Peronochaeta dubia, and Canadia setigera, now Burgessochaeta setigera, both genera of Conway Morris (1979). A specimen included in Walcott's C. dubia later became Stephenoscolex argutus Conway Morris (1979).
Of the others, Canadia sparsa became Hallucigenia sparsa, as redescribed by Conway-Morris (1977), but later was famously interpreted the other way up, and head to tail reversed, and thought to be a lobopod, (a stem onychophoran), as is Aysheaia pedunculata. Wiwaxia corrugata is currently not placed as an annelid, lacks segmentation, and is probably a stem mollusc. Selkirkia are thought to be a priapulids, as is Miskoia preciosa. Pollingeria grandis is a Problematica unknown. Worthenella cambria is a multi-legged arthropod. Ottoia (then in Gephyrea) are still Priapulida (or alternatively Enteropneusta), so Walcott correctly placed them, and Pikaia gracilens is a primitive chordate. The remarkable Banffia constricta is thought to belong to an extinct phylum called Vetulicolia. Oesia disjuncta is still a Problematica, but has been placed as hemichordate.
Insolicorypha psygma Conway Morris, 1979 is a subsequently discovered Burgess Shale stem polychaete.
Sources: see paleodb.org, burgess-shale.rom.on.ca, also Conway Morris (various) and Danny Eibye-Jacobsen (2004).
> -----Original Message-----
> From: annelida-bounces from oat.bio.indiana.edu [mailto:annelida-
> bounces from oat.bio.indiana.edu] On Behalf Of Geoff Read
> Sent: Wednesday, 14 December 2011 11:54 a.m.
> To: annelida from net.bio.net
> Subject: [Annelida] Burgess Shale site
> Hello & FYI,
> A new site about the Burgess Shale fossils and the fossil beds' location in the
> Canadian Rocky Mountains, curated by the Royal Ontario Museum.
> Nice work.
> "The Burgess Shale refers to a fossil-rich locality on Fossil Ridge between Wapta
> Mountain and Mount Field, just a few kilometres north of the small town of
> Field, British Columbia. Charles Walcott coined the term to describe various
> fossiliferous rock layers with soft-bodied preservation that he found in 1909 and
> 1910 and excavated for several years thereafter. The most important
> excavations were made within a two-metre-thick section representing a series
> of layers containing the most exquisitely preserved soft-bodied fossils. This
> section was named the "Phyllopod bed" by Walcott, in reference to the leaf-like
> structure of the appendages of certain abundant arthropods, including Waptia."
> If you want Walcott's (1911) original Cambrian annelids paper it is available at:
> Online: http://www.biodiversitylibrary.org/page/9263167
> BHL pdf generated by GBR:
> Which of Walcott's fossil taxa are close to annelid clade, and which are not? You
> tell me.
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