Sunday, September 29, 2013

Pentamerella (?) from Alpena, Michigan

A few weeks ago I posted the photo's below on the Fossil Forum in the hopes that someone would recognize the fossil and help me name it. You see, it came into my collection as part of a lot of material that was labelled "Alpena, Michigan". That description covers a large area and several geologic formations so if I can't recognize the specimen I have to go digging for info. Here are some of the pics I took of the specimen:

Brachial valve


Pedicle valve


 Right profile with pedicle valve on top

 Left profile with brachial valve on top

After I posted them on the forum one member, Fossilcrazy, suggested it might be Camarotoechia pauciplicata based on David M. Linsley's "Devonian Paleontology of New York" (Pg.188 Plt. 83 Items 1-5). This seemed like a good fit except that my specimen lacks a fold and sulcus (the divot that is often seen in the middle of some brachiopods).

Another member, Plantguy, took it upon himself to reach out to some experts and came back with the following:

Dr. Lindsey Leighton, of the University of Alberta, responded:
I have collected a lot of brachs from the Devonian of the Alpena region, as well as Ontario and New York, and I have never seen that particular brachiopod. It does not look like a typical Camarotoechia, but it is possible that the species is atypical for the genus. Camarotoechia, by definition, should have a fold and sulcus present the length of the brach, and based on the photos, I don't really see a fold and sulcus at all. Similarly, I don't see any costae (ribs), which again, is part of the genus definition. But this could be that I can't see the relevant features on the photo. The combination of weak to absent fold and sulcus, and the lack of costae, is a little weird. My best guess is that it is not a rhynchonellide at all, but something in the Pentamerida, possibly some odd species of Pentamerella or Gypidula, but it doesn't quite look right for either of those two genera either. There are leiorhynchids that have a more or less naked (lacking in ornament such as ribbing) umbonal area and few plicae, so it might still be a rhynchonellide of some sort.
Dr. Leighton suggested contacting Dr. Jed Day, of Illinois State University, who subsequently reviewed the pictures and came back with this:
Your specimen appears to be crushed near the posterior end of its lateral margin and may be a juvenile specimen of one of two things I know of from eastern side of the Lower Peninsula area. The only things I know of that look like the specimen (s) you show in the photos are from the Ferron Point (Pentamerella lingua, Imbrie, 1959) and Norway Point (Pentamerella pericosta, Imbrie, 1959) formation quarry and natural exposures in Alpena County (See old Guidebook series, Ehlers and Kesling, 1970) . There are a number of other pentamerids that have been described from the west side of the LP that also resemble the specimen described in the older litherature (Imlay, etc.). There also rhynchonellids that it might be, especially Eumetabolotoechia.
Here is  specimen of P. lingua from the Ferron Point Fm. on the Michigan Basin Fossils website: They have a specimen of P. pericosta as well: The former appears to be the closest match to what I have although the width of my specimen is less than those pictured. Maybe that is because part of the one side is slightly crushed or this is a juvenile specimen.

In any case this has been an interesting mystery and may not yet be solved. For now I am labeling my specimens as Pentamerella lingua.

Friday, September 27, 2013

Odds and ends fossils from St. Petersburg, Russia

This is the last of my posts regarding fossils from the Ordovician rocks near St. Petersburg, Russia for now. The fossils I'm showing today are partials and lesser examples that don't merit a full blog entry.

First up is this odd looking piece which I believe is the interior of a pedicle valve from a strophomenid type brachiopod.It has the characteristic half-moon shape and I think that the relief seen near the one side of the fossil represents some muscle scars.

Next is this Graptolite which may only be a part of a larger colony. The rounded end does look like it is supposed to naturally occur like that but the other end seems to have extended farther at one time.

Lastly is this cast of a cephalopod. It is interesting because of the slanted or spiral like pattern. This could be an impression of the exterior decoration of the shell rather than the usual internal vertical chambers. Three sides are preserved with the fouth filled with Calcite.

Hopefully I'll get some more fossils from the St. Petersburg region in the future. I don't have enough to really compare to those that I've found in here in the US or Canada.

Wednesday, September 25, 2013

Lonchodomas and Illaenus trilobites from St. Petersburg, Russia

I'm winding down on my Ordovician fossils from Russia. Today we have some partial trilobites from the Ordovician aged rocks near St. Petersburg, Russia.

First up are three partial specimens of Lonchodomas volborthi from the middle Ordovician (Dapingian stage of the ICS, Volkhovian stage locally) of Putilovo quarry, St. Peterburg region, Russia. Two are thorax and pygidium specimens:

The third is a partial cephalon that is missing it's spines. There should be one on the tip of the glabella and one each coming off the side of the cephalon. I am very interested in the fact that there are two differently colored areas on the sides of the glabella that are mirror images of each other. It seems that this is not uncommon for this genus from this location either as evidenced by specimens that are posted on the (Saint Petersburg Paleontological Laboratory) website.

The chunk of rock that the cephalon is on has quite a few Ostracods preserved in it as well.

The second trilobite I have to show today is Illaenus sp. (Dapingian stage of the ICS, Kunda stage locally). I don't know the exact location for this specimen as it came mislabeled as Asaphus lepidurus. It is not in the best shape but I received it as part of a trade so it will have a place in my collection until I can afford a better specimen.

There are 30 different species for this genus listed on the Baltoscandian Fossils website here, so I don't know if I will ever be able to nail down the species on my specimen. Looking at the first picture of this specimen reminds me of the Thaleops cephalon I found in the Verulam fm. in Canada.

Monday, September 23, 2013

Leptaena sp. brachiopod from St. Petersburg, Russia

Another of my recently acquired fossils from Ordovician of St. Petersburg, Russia is this Leptaena sp. brachiopod.  Looking through the Baltoscandian Fossils website there are a large number of species listed for this genera. Based on the shape of the shell this could be Leptaena rhomboidalis.

Pedicle valve
Anterior (note that the left side of the valve is broken away)
Right profile

Saturday, September 21, 2013

Conularid from St. Petersburg, Russia

This is a 3-D fossil of a Conulariid from the Ordovician rocks near St. Petersburg, Russia. It is well preserved and has a bumpy detail to the surface in addition to the normal lines that decorate such shells.

I took pictures of the shell all the way around with each pic showing the specimen rotated 45 degrees to the left. 

Lastly a shot down the length of the specimen showing the nearly perfect square shape.

The specimen came from the Putilovo Quarry (more famous for it's trilobites) whose rocks are middle Ordovician in age (part of the Volkhov stage in the Baltic or the Dapingian stage in the ICS timescale).

Thursday, September 19, 2013

Geniculina pseudoalternata(?) brachiopod from St. Petersburg, Russia

This is a Strophomenid type brachiopod that has a growth style similar to some Leptaena sp. specimens. The shell edges grow outward normally for a time and then turn ninety degrees like a cloth draping a table.

Pedicle valve (are those little holes Trypanites borings?)

The rest of the shell is imbedded in the rock so I have two profile views instead.

Left profile (I like the bryozoan epibonts that have colonized the exterior of the shell)

Right profile

This specimen comes from the Ordovician ages limestones near St. Petersburg, Russia but the ID that was included with it is incorrect. I was told that it is a Clinambon sp. but a review of the Baltoscandian Fossils web site finds a completely different fossil. So I looked through the site's archives and found a possible match in Geniculina pseudoalternata. What do you think?