Friday, July 29, 2016

Spathites puercoensis ammonite from the Mancos shale of New Mexico

Here are another couple of Ammonites from the Carlile shale member of the Mancos Shale (Turonian stage of the Cretaceous) of Sandoval County, New Mexico. They are specimens of Spathites puercoensis. This ammonite is small but somewhat robust with some obvious ribs near the keel.  Each whorl overlaps the previous by about 95%. As these are steinkerns and no original shell is left, the suture pattern is easily visible and consists of a number of alternating "U" shapes, of differing depth, accented with some smaller zigzags.

Specimen #1
Right side

Left Side

Keel


A cross section view of the last suture chamber

Specimen #2
Left side

Right side (note the rock plug in the center which indicates there were likely more whorls that eroded away before the fossil was found)

Keel

Cross section view of the last suture.

A closer view of the suture pattern.

The publication "Contributions to Late Cretaceous Paleontology and Stratigraphy of New Mexico Part II". Bulletin 114. New Mexico Bureau of Mines and Mineral Resources. contains a paper by W. A. Cobban titled "The Late Cretaceous ammonite Spathites Kummel and Decker in New Mexico and Trans-Pecos Texas" from which this illustration of the suture patterns of S. puercoensis comes.


Thanks to Mike (PFooley on the Fossil Forum) for this fossil that he offered up as part of an auction to help defray some of the operating costs of the Fossil Forum website.

Tuesday, July 26, 2016

Coilopoceras springeri ammonite from the Mancos Shale of New Mexico

Today I have an Ammonite from New Mexico to show you. It's a Coilopoceras springeri from the Carlile Shale member of the Mancos Shale (Turonian stage of the Cretaceous), Sandoval County, NM. The fossil is very thin in cross section, it reminds me of a frisbee, and has a very complex suture pattern. Each whorl overlaps the previous whorl by about 95%.

Right side
Left side

Keel

 A closer detail of the keel from the side. I'm not sure if the segmentation that is shown is part of the shell or just an erosional feature.

 Keel with a cross section view of the last suture chamber.

A closer view of the suture pattern.

I found a publication, "The Upper Cretaceous (Turonian) ammonite family Coilopoceratidae Hyatt in the Western Interior of the United States." W. A. Cobban and S. C. Hook. 1980. United States Geological Survey Professional Paper 1192:1-28, that has a good description of this species and this helpful drawing (figure 11, page 18) of a few typical suture patterns from C. springeri specimens.


Thanks to Mike (PFooley on the Fossil Forum) for this fossil that he offered up as part of an auction to help defray some of the operating costs of the Fossil Forum website.

Saturday, July 23, 2016

Erbenoceras solitarium goniatite from Morocco

The Goniatite I am writing about today also comes from Morocco and have a very simple suture pattern. I used a webpage in Japan, hosted by Gifu University, to help identify it as Erbenoceras solitarium  This specimen has tall whorls that are subrectangular in shape and do not overlap prior whorls much.  The suture pattern is a very gentle curve and appears to be very simple. I don't know what part of Morocco this comes from but I believe it's Devonian (Famennian stage) in age. The central whorls are missing in this specimen but much of the living chamber is present.

Right side

Keel

Left side with some extra, granular pyrite crystals growing over much of the fossil.

Keel with the living chamber cross section.

Thursday, July 21, 2016

Kosmoclymenia sp. goniatite from Morocco

Here is another pyritized Goniatite from Morocco that I was able to identify using a webpage in Japan, hosted by Gifu University, that has a very comprehensive and illustrated page of Goniatites that appear to be from Morocco.  It's called Kosmoclymenia sp. and has narrow, rounded whorls with a very simple suture pattern that kind of looks like Harry Potters forehead scar. I don't know what part of Morocco this comes from but I believe it's Devonian (Famennian stage) in age.

Left side

Keel

Right side (with some matrix still to be removed)

Keel with the last suture chamber (possibly the living chamber?).

Wednesday, July 13, 2016

Cymaclymenia sp. goniatite from Morocco

Here is another pyritized Goniatite from Morocco that I am calling Cymaclymenia sp.  This is based on the same Facebook lead that helped me ID the Prionoceras lentis specimen in the previous post.

There are a number of pictures on the internet of specimens with a similar suture pattern to the specimen shown below and most are called Cymaclymenia.  The suture pattern is very distinctive with a square notch like shape located a little more than halfway towards the keel. I am not sure of the species as I don't have any good locality information but I believe this comes from the upper Devonian (Famennian stage).

Left side


Keel

Right side

Keel with last suture chamber visible.

In the course of my research I found a webpage in Japan that has a very comprehensive and illustrated page of Goniatites that appear to be from Morocco. It is hosted on the Gifu University site and the link above is to a page that shows an illustrated list of genera from the lower Devonian through the upper Devonian. I can't find any information on who created or maintains the site but I certainly appreciate it's presence.