Saturday, March 31, 2012

Megastrophia from the Windom Shale

Megastrophia are very large shells and when one gets an intact specimen you are lucky. I had some luck on my side when I uncovered the Megastrophia below at the Penn Dixie site near Blasdell, New York. I took extra care to excavate the rock around it so that it wouldn't break apart as I extracted it. As it is I soaked it in a thin solution of Elmer's glue and water to help strengthen the fossil.

Pedicle valve


I'm not sure if both valves are present with this fossil as it is so delicate I don't want to work on it. It was collected from the Windom Shale member of the Moscow formation which is middle Devonian (Givetian) in age.

Thursday, March 29, 2012

Pseudoatrypa from the Windom Shale

I was surprised at the large size of the Pseudoatrypa that I found at the Penn Dixie site. Specimens the size of a walnut are very common and found in the same layers that Spinatrypa occurs.

Pedicle valve


Brachial valve



Specimen #2
Pedicle valve


Brachial valve



As a comparison, here is the second specimen of Pseudoatrypa next to a Spinatrypa from the same layer. The Spinatrypas seemed to get larger than the Pseudoatrypa.

The specimens shown above came from the Windom shale member of the Moscow formation which is middle Devonian (Givetian) in age.

Tuesday, March 27, 2012

Spinatrypa spinosa from the Windom Shale

While exploring the Penn-Dixie site near Blasdell, New York, I was digging in an area referred to as "The Brachiopod zone". I had been guided to this area by my friend Carmine who said that lots of Brachiopod fossils could be found at certain level. While most collectors visit the site to look for Trilobites, I was more interested in the other fauna that could be found so I headed to the suggested area. After a few minutes digging in the soft shales I started to pull out huge Brachiopods. One of the more common fossils was Spinatrypa.

Pedicle valve


Brachial valve



The fossil above is the typical way they are found but sometimes, if you are careful or lucky, you get one with the spines (of it's namesake) preserved such as the specimen below.

Here are the two fossils side by side. You can see they are about the size of a half dollar coin.

These are the first Spinatrypa spinosa that I've collected and among the largest brachiopods in my collection. The rock layers exposed at the Penn Dixie site are middle Devonian (Givetian) in age and are the Windom shale which is a part of the Moscow formation.

Sunday, March 25, 2012

The Penn Dixie Paleontological and Outdoor Education Center

If you are a fossil collector, then Buffalo, NY is a great place to visit. Forget the Niagara Falls, there are so many roadcuts and creek beds to explore nearby! One of the best places to visit and collect is at the Penn Dixie Paleontological and Outdoor Education Center. This is an open, relatively flat area where many layers of the Moscow formation are exposed at the surface of an old gravel pit. The Hamburg Natural History Society runs and maintains the site as a natural and paleontological resource. Anyone can come and collect fossils there and it's safe for all ages since there are no steep walls.

Here is a panorama of the site (click to make it larger):

The geology exposed has been studied and charted by the club to produce this stratigraphic view:

The diagram has an exaggerated elevation so that more details about the layers can be illustrated but what it does show is how the layers dip gently to the southeast. The southernmost parts of the site, near the asphalt walkway above, have the youngest layers.

Most of the digging on site is focused on the "Smoke Creek Trilobite Bed" where Phacops and Greenops trilobites are fairly common.  The club maintains the site and occasionally will come in with a bulldozer to clear spent rock and expose more of the desired layers. Here is a group working the trilobite bed:

Any of the rocks lying on the ground in the above picture could hold a trilobite. If you don't want to work the exposed layers then you can take a turn at cracking the debris pile.

Just below the trilobite bed is the Tichenor limestone which is a very hard and resistance layer. You can find outcroppings of the layer near the northeast corner of the site where the water drains off.

The water has carved some deep channels which look like miniature canyons.

You can easily spend a few hours at any one point on the site exploring the many exposed layers and fossil zones. Some of the fossils I've found at the site are: Ambocoelia, Athyris, Emanuella, Mediospirifer, Mucrospirifer, Pseudoatrypa, Rhipidomella, Spinatrypa, Megastrophia, Phacops, Greenops, Amplexiphyllum, Aulocystis, Stereolasma.

Friday, March 23, 2012

Conostichus trace fossils

Today I have some odd trace fossils to show you. They are called Conostichus and come from the Pennsylvanian rocks of Texas. Most often found as conical shaped masses of sediment Conostichus are thought to represent the infilling of a burrow of some sort.

These were some odd fossils and I know very little about them and what they were. I posted pictures of these oddball fossils to the Fossil Forum to see if anyone could help me out. I got a lot of good responses especially from my friend Barry (Indy is his forum name) who pointed out that:

Conostichus (a fossil with a confusing history) was formerly thought to be a jellyfish resting trace. It is now regarded as a burrow infilling or feeding structure of an unidentified organism. These fossils were first described by Lesquereux in 1876 as a marine algae and then by later authors
as roots, stems, sponges or worms. C.C. Branson wrote a number of articles circa 1956/1962 in which he discusses numerous separate species. In a 1959 article he states "It is possible to state at this time that the genus Conostichus has but one species, C. ornatus; that some of the marine specimens may be medusoids; that some of the types are probably marine worms. Close examination of specimens in place in the rock and of the associated biota is necessary to a real understanding of these four similar types of fossil." In later articles he describes a number of new species. Joeckel, 2008 states "A trace-fossil hypothesis for the origin of the structures remains plausible...possible feeding structures---albeit problematic".
Barry is a smart guy and has his own website filled with good reading about his local rocks in the Missouri area at Paleontology and Geology of Missouri.

Here is another specimen of Conostichus that shows a slightly different shape and structure.

I don't have much locality info to go on with this specimen. All I could find with the label was "Pennsylvanian" and "Texas". I think it might be from the Finis Shale but I can't be sure.

Wednesday, March 21, 2012

Dakoticancer australis crab from Mississippi

The last of the fossils that was given to me by my friend Don, during a visit last fall, are these Dakoticancer australis crab fossils. He found these in the Coon Creek formation near Blue Springs, Mississippi.

This first one was preserved by Calcite and is pretty much just the upper and lower body carapace.

This second specimen is more complete and I think is preserved by phosphates rather than Calcite.

The Coon Creek formation is dated to the lower Masstrichtian stage of the upper Cretaceous.


And here is one on the Coon Creek formation paleoenvironment and depostion.

Monday, March 19, 2012

Nucula percrassa from Mississippi

Another interesting fossil I received from my friend Don were a couple of individual valves from a Pelecypod called Nucula percrassa. The neat thing about them is that the mother of pearl has been preserved for the last 65 +/- million years.

Here you can see the shine of the mother of pearl (or nacre) on the interior of the shell. In daylight there is a faint pink sheen which is not picked up well by my camera.

This shell came from the Coon Creek formation near Blue Springs, Mississippi. The Coon Creek formation is dated to the latest Cretaceous (Maastrichtian stage).

Saturday, March 17, 2012

Hardouinia bassleri echinoid from Alabama

From the Cretaceous (Santonian stage) Tombigbee Sand Member of the Eutaw Formation in Montgomery county, Alabama comes this echinoid called Hardouinia bassleri. I received it as a gift from a visiting friend from Georgia.

Adapical surface (top)

Posterior (rear)

Side profile

Side profile

 Adoral surface (underside or bottom)

Thanks to Don for the fossil!

Edited 09/26/14

Thursday, March 15, 2012

Zamites feneonis fossil cycad from France

I don't have many plant fossils from the Mesozoic era so I was pleased when I received a specimen of Zamites feneonis in a recent trade. Zamites was a genera of Cycad that lived during the upper Jurassic period (Kimmeridgian stage) near the coast of the Tethys ocean in what is now alpine France (the Jura mountains) near Geneva.

This fossil came from a site near the "Orbagnoux deposit" which is a well known and studied occurrence of Kerogen (an early stage in the formation of Hydrocarbons). Kerogen forms from the organic remains that are preserved in rocks. Depending on the amount present and the temperature and pressure it's effected by, it can form gas or crude oil. But usually it just forms bitumen which is often found as a black, oily smelling coating within cracks and along joints within rocks.

If you want to see some other pics of Zamites and learn more about the deposit, click here. It will take you to a French website that you will need a translation program like Babelfish to read.

Thanks to my friend Christian for sending me this specimen.

Tuesday, March 13, 2012

Eupatagus echinoid from Spain

This is an Eupatagus aragonensis echinoid that I received in a trade. It's from the Eocene (Lutetian stage) and was found near Alicante Huesca, Spain.

Adapical surface (top)

Posterior (rear)

Side profile

Anterior (front)

Adoral surface (underside or bottom)

This is an interesting fossil in that it has features from several different types of echinoids that I have seen. It's an irregular urchin since it is not round shaped and it's fairly flat like a sand dollar. Also, the test (skeleton) has both large and small tubercles which is where the spines would attach.

Thanks to my friend Jenaro for this fossil.

Monday, March 12, 2012

Cyzicus clam shrimp from the Lockatong formation

Where I live in Pennsylvania, the underlying bedrock is Triassic aged lacustrine deposists lain down when Pangea was splitting apart. Not many fossils are found but occasionally fish, reptiles, plants and dinosaurs are discovered. While exploring a building foundation excavation near my house I found some black shale which has shiny shells on the surfaces.

Above is a piece with both the front and back covered with the shells. It turns out that the shells are of a freshwater Conchonstracan called Cyzicus. It's an crustacean similar to ostracods but more closely related to shrimp. It been nicknamed the "Clam Shrimp" since it has two chitonous shells that enclose the body.

Here are some closer views of the shells that I took with my Zorb micro imager.

Here is a page with a nice anatomical picture and description plus some other fossils.

This page has links to a whole series of pages with more information about Conchonstracans.