Cleoniceras besairei ammonite from Madagascar

Celoniceras besairei ammonites from Madagascar are very common on the fossil market. They come from Albian stage (Cretaceous) aged rocks on the northwest coast in a region called Mahajanga. The specimens below retain some of their original shell material (or nacre) and are colorful in the sun. Generally specimens such as these need to be worked before they can leave Madagascar. The idea being that it will help employ more people in this poor country. In the case of these specimens they hav had some of the shell trimmed to make it flat and even. They likely removed jagged and incomplete edges to make the shell look better. Many times they polish the shell material off, to reveal the sutures underneath or sometimes a layer of gemmy fire opal, or cut them in half to show off the interior chambers like in these specimens that I posted before (and I think may not be Cleoniceras but rather Desmoceras because of the internal suture shape).

Specimen #2 - this one is a little rougher with some shell sections missing but it looks more like it was "just found" rather than all polished up.

This web site has a nice write up of their experiences collecting and cataloging the ammonites of Madagascar. It's in German but Google translate will help.

Tylothyris mesacostalis brachiopod from the Chemung group of New York

A new spirifirid type brachiopod in my collection is this Tylothyris mesacostalis which comes from the Upper Devonian, Chemung Group near Painted Post, NY. The specimen is a internal cast of the pedicle valve with some other brachiopod casts around it. What I can see is a valve that is wider than it is long, is deep and has a straight interarea on the posterior. The "beak" that you can see at the top of the fossil is very indicative of Spirifer type brachiopods. That is where the pedicle muscle was located with the empty space on either side of the "beak" representing portions of the shell that dissolved away.

Pedicle valve

Anterior

Profile

Posterior

The Chemung Group is a broad term used to describe a series of rocks that have a similar fauna that existed in the upper Devonian. It consists of many different formations but the label I recieved with the specimen does not have anything more specific other than the locality. Given Painted Post as the "location" of the fossil, it's a little west of Corning, NY, I can look at a geologic map and see that the possible source rocks could be the Nunda Formation, West Hill Formation or Gardeau Formation. All of those formations crop out in the nearby vicinity of Painted Post but as I have no experience collecting in them I can't narrow down the source formation. I received this fossil via trade with someone who had purchased it at an open house sale at the Rutgers Geology Museum.

Pentamerella arata brachiopod from the Schoharie Formation

Another fossil I acquired from the trade that netted me some ex Rutgers Museum of Geology material are these Pentamerella arata from the Schoharie Formation (part of the Onondaga Limestone, lower Devonian) near New Salem, NY. They are just isolated pedicle valves but the ornamentation and overall shell shape is preserved enough for ID.

Pedicle valve

Anterior

Profile

Posterior

Specimen #2 - Pedicle valve

Left profile

Anterior

Right profile

Posterior

Underside view of the interarea and delthyrium

Eutrephoceras sp. nautiloid from the Pierre Shale

As part of a recent trade I received a large nautiloid fossil from the Pierre shale called Eutrephoceras. It has a catalog number marked on it which indicates it came from the Rutgers Geology museum and was deaccessioned during one of their open house surplus sales programs. The fossil is in good shape with some original shell in place while other areas have none which allows the sutures between individual chambers to be exposed. I don't have any other locality information for this fossil but I suspect it came from somewhere like South Dakota or Wyoming. Information that I find online indicates there is a species called Eutrephoceras dekayi found within the Pierre Shale in those areas that is dated to the Masstrichtian stage of the upper Cretaceous.

Leiorhynchus multicostus brachiopods from the Levanna Shale

I came upon this plate of shale in a small quarry near the town of Fayette in New York. It comes from the Levanna Shale of the Skaneateles Formation and is covered with brachiopod fossils called Leiorhynchus multicostus (aka Eumetabolatoechia multicostatum). Leiorhynchonellid type brachiopods are often common in black shales which indicate that they were tolerant of conditions with lower oxygen content. In this case there must have been a period or time where the conditions were right and the L. multicostus proliferated. Some of the layers below the surface shown in the first picture also contain a profusion of this brachiopod such that the environment was somewhat stable for many years even during deposition of fresh sediment. Normally the Levanna shale is fairly barren of fossils with only a few scattered remains that may have been washed in by storms. Only occasionally do you find layers with such an abundance of fossils.

View of the shale piece with the top layer in place

Close up of top layer

This is a thin piece of the top surface layer flipped over to show more brachiopods underneath.

Closeup of the same piece

Yet another layer within the shale, again with many brachiopods.

I've posted an inflated specimen of the same species here that I found near Arkona, Ontario.

The Levanna Shale and Skaneateles Formation are middle Devonian in age (Givetian stage).