Taxonomy of Lingula from Collingwood

[Arion]

The brachiopod Lingula is locally abundant in the Whitby Formation around Craigleith, Ontario (frequently around the Triarthrus horizon). I have about a dozen specimens of Lingula from the Craigleith/Collingwood area in my collection, and have previously identified them as Lingula cobourgensis based on this: http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/GB07/GB07.pdf

This evening, noting that in Liberty's (1969, Palaeozoic Geology of the Lake Simcoe Area) faunal list for the Whitby Formation only Lingula progne was recorded as being present, I decided to do a bit of research on L. progne. In the process, I came across Sinclair's (1945) work Some Ordovician lingulid brachiopods from Ontario and Quebec. Sounds promising, I thought. In this paper, Sinclair names several new species of lingulids, and makes some interesting observations on lingulid taxonomy. At the time, he acknowledged that some taxonomic decisions were more "a matter of subjective judgement rather than of application of objective criteria" and that "If fossils similar to Ordovician species turn up in the Devonian, as they do, there is the presumption that the animals must have been different, even though their shells cannot now be distinguished." (p. 6)

However, what I found really interesting were his comments on Collingwood-area lingulids, in particular Lingula progne. Billings' original description of L. progne was of material from the "Trenton limestone" of Montreal area, but his figures were of material from Collingwood, which Sinclair notes is different from the Montreal specimens. "The name [Lingula progne] has been applied since, on the basis of the figures of a shell with prominent septum, to shells common in the Collingwood shale." (p. 38) Subsequently, Sinclair describes the Collingwood L. progne material as a new species, Lingula divulgata:

Detail of shell surface:

Both of these very closely resemble the lingulids from Craigleith area in my collection. I haven't done a character-based comparison of my specimens with Sinclair's description, but I haven't found any other information on Sinclair's species beyond his original description (Liberty [1969] doesn't mention it, it's not in the Paleobiology Database, etc.).

So, my question is: what happened to Lingula divulgata? Is it considered a junior synonym of L. cobourgensis? Or was it just forgotten?

Edited August 24, 2016 by Arion

[piranha]

Sinclair's figures of Lingula divulgata are not very useful.

I found a much better quality example from Bolton 1970:

 

 

Lingula sp. cf. L. divulgata Sinclair

Vauréal Formation, Upper Ordovician.

Carleton Point well, depth 1,131 feet.

Hypotype, GSC No. 24601.

 

Bolton, T.E. (1970)

Subsurface Ordovician fauna, Anticosti Island, Quebec.

Geological Survey of Canada Bulletin, 187:31-41

 

 

 

[Ridgehiker]

I have no idea as to the answer to specifics of your question. However, a lot of Lingula have been reassigned to other genera. Its may be useful to search for the species and find the genus under the family Obolidae. The species name stays the same. The genus 'lingula' is a catchall hodgepodge.

Personally I don't get caught up in the identification of inarticulate brachiopods. I note the location, formation.. The rest is somewhat speculative assignment of genus and species based on inconsistent naming within this subclass. We don't look at the inarticulate brachs in a study other than to note their presence. In most formations there just isnt any stratigraphic value as the internal structure is usually not all that diagnostic.

An aside...I have a couple of extant Lingula brachs in my modern shell collection. Somewhat incredible how externally they haven't changed.

Edited August 24, 2016 by Ridgehiker

[doushantuo]

Emig/Holmer/Popov,etc

e.g.:

https://www.researchgate.net/publication/298434339_Reassessment_of_the_early_Triassic_lingulid_brachiopod_'Lingula'_borealis_Bittner_1899_and_related_problems_of_lingulid_taxonomy

Edited August 24, 2016 by doushantuo

[tmaier]

Extant Lingula next to Cambrian Lingula (from Conasauga Shale of Georgia)...

Wow. Sure nuff looks like a living fossil, don't it?

(he snickers and dashes for the nearest door...)

____________________________________

And here's an Obolidae from the same layer in the Cambrian Conasauga Shale...

Sorry about the grainy picture quality, these are from the early days of digital photography, and were OK for their time.