What species of spirifer?

[tombk]

Greetings! I went on a quick (~60 minute) hunt today on the Iowa River in Iowa City, Iowa. The rocks there are from the Coralville Group of the Cedar Valley Formation (Devonian), mostly limestone and dolomite. I hope to post a brief summary in the Trips forum soon. I didn't find much, but one thing I did get is a large spirifer of some sort. I'm excited about it because it contains both valves, with pretty good preservation of the entire ventral valve and good preservation of one "wing" of the dorsal valve. It measures about 10 cm from tip to tip (sounds better than from cardinal extremity to cardinal extremity). Any ideas on the species?

 

Ventral valve:

 

Beak:

 

Dorsal valve (the right side isn't as well preserved as the rest of the specimen):

 

Thanks for your help!,

 

Tom

[Fossildude19]

You might try getting the paper   "Spiriferacea of the Cedar Valley Limestone of Iowa  Merrill A. Stainbrook 1943"

 

[Misha]

That's quite a beauty! Platyrachella sp. perhaps?

@Tidgy's Dad

[tombk]

9 hours ago, Fossildude19 said:

You might try getting the paper   "Spiriferacea of the Cedar Valley Limestone of Iowa  Merrill A. Stainbrook 1943"

Thanks, at your suggestion I got a copy. It’s just what I needed. My specimen looks like a Spirifer iowensis (1-3 below from the paper).

[tombk]

7 hours ago, Misha said:

That's quite a beauty! Platyrachella sp. perhaps?

You may be right. These are found in Iowa’s Cedar Valley Formation. I have a hard time distinguishing between some Platyrachella species and some Spirifer species. I’m still leaning towards Spirifer iowensis though which, according to my newly found article suggested by @Fossildude19, are very plentiful where I found this specimen. 

[minnbuckeye]

 

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Maybe @Tidgy's Dad can explain to us the difference between Sirifer iowensis and Playrachella iowensis. I have labeled all of my specimens Platyrachella.

  

Mike

[Tidgy's Dad]

You are all sort of correct. 

The paper is from 1943 and since then many species of the waste basket taxon "Spirifer " have been placed in other genera.

1 hour ago, tombk said:

"Spiriferacea of the Cedar Valley Limestone of Iowa  Merrill A. Stainbrook 1943"

So, Spirifer iowensis is now Platyrachella iowensis. 

[minnbuckeye]

@Tidgy's Dad, THANK YOU!!!!!!!!!!!!!

[tombk]

1 hour ago, Tidgy's Dad said:

The paper is from 1943 and since then many species of the waste basket taxon "Spirifer " have been placed in other genera.

Thank you @Tidgy's Dad! I don’t suppose it’s going to be as easy as looking up an ID in the 1943 paper, and then changing the “Spirifer” into “Platyrachella” or “Orthospirifer.” Is the genus Spirifer still used for some species? Do you have any suggestions for up to date, North American, Devonian brachiopod ID references? Or is it a matter of gradual accretion of knowledge and more narrowly focused journal articles? 

Edited August 30, 2021 by tombk
Addition of term

[Tidgy's Dad]

The Treatise on Invertebrate Palaeontology is useful to get specimens down to generic level, but for details on individual species you would need to gradually acquire a collection of papers either looking at the fauna of an area or formation, or each taxonomic unit of brachiopods. And names change quite often, so old papers need to have the names checked.  

[Tidgy's Dad]

Oh, I forgot. 

Yes, Spirifer is still a valid genus, though the number of species has been greatly reduced over the years. 

[tombk]

7 hours ago, Tidgy's Dad said:

The Treatise on Invertebrate Palaeontology is useful to get specimens down to generic level

I just looked this treatise up. Wow. 6 volumes for brachiopods alone! I suppose possession of The Treatise on Invertebrate Paleontology, like knowledge, builds slowly.