Thursday, August 30, 2012

Plicathyris brachiopods from Spain

I've been fortunate to be able to trade with a friend in Spain for some interesting brachiopods from the Devonian. Below is Plicathyris collensis from the Coladilla formation of Spain.

Brachial valve
Pedicle valve

Here is another species called Plicathyris ezquerrai.

Brachial (?) valve


Pedicle (?) valve


Compare this fossil to the previous one, and you see the main difference is the width of the shell.
The Coladilla formation is lower Devonian in age (Emsian stage) and is part of the La Vid group from Colle which is near Leon in Spain.

Thanks to my friend Jenaro for this fossil.

Tuesday, August 28, 2012

Ammonites from Caen, France

A number of Ammonite species are found in the region around Caen France. The rocks are Jurassic (Toarcian to Callovian) in age and between quarries and farm fields, quite a few specimens can be found.

Parkinsonia parkinsoni Bajocian stage (169 mya)

Hildoceras bifrons Toarcian stage (180 mya)

Perisphictes sp. Bajocian stage (169 mya) - This specimen has Quartz crystals that formed within the voids between chambers.

Oppelia subradiata Bajocian stage (169 mya)

Stephanoceras sp. Bajocian stage (169 mya) Like the Perisphictes above, this specimen has Quartz crystals that formed within the voids between chambers also.

A second, smaller specimen.

My thanks to Gery for sending me all of the above specimens.

Sunday, August 26, 2012

Gryphea from France

Oysters are fascinating animals because of the variability of the shells. In the Jurassic they took on many forms and some were called "Devils Toenails". One such shell belongs to Gryphea. This genera has coiled shells with one valve that is relatively flat while the other is deeply concave. This specimen comes from the Lower Jurassic (Sinemurian) rocks near Atton in the providence of Lorraine, France

Another example is Gryphaea dilatata which has a much larger and wider shell. It is also notable that the valves have a similar curve to them but only one "curls". This species if from the Upper Cretaceous (Oxfordian) of Villers Sur Mer in the providence of Normandy, France.

Other members of the genera went on to have even more curled shells like Ilymatogyra or became more flattened by turning on their sides like Texigryphea navia. Then again, some didn't change much at all like Texigryphaea marcoui.

Friday, August 24, 2012

Burmirhynchia hopkinsi

Another fine brachiopod from the Jurassic (Bathonien) aged cliffs near Luc Sur Mer, France is Burmirhynchia hopkinsi. This species is related to Burmirhynchia decorata but is smaller and flatter.

Group shot of several specimens

Pedicle valve

Anterior (front)

Brachial valve

Posterior (Rear)


Thanks to my friend Gery for sending me these fossils.

Wednesday, August 22, 2012

Ordovician fossils from the Coburn formation

Ordovician aged fossiliferous rock exposures are somewhat uncommon in Pennsylvania. Most of the exposed rocks are Devonian to Pennsylvanian with the rest buried underneath. Besides the, now closed and eliminated, Swatara Gap locality the next best area to collect Ordovician fossils is up near State College. There is a thick exposure of rock from the Reedsville formation down through the Loysburg formation along US322 at the Reedsville exit. Not all the rock is fossiliferous but parts of the Coburg and Nealmont formations are good to hunt in. The sequence is mostly Middle Ordovician and records a shallow sea that is gradually deepening and then being filled in with continental sediments during the Taconic Orogeny. This is seen by the sequential deposition of limestone followed by black shales and then sandstone.

Here is an aerial view of the area with geology overlaid....

...and the annotated version

The fossils that I found were in thin to medium thickness limestones which belonged to the Coburn formation.

Orthoconic nautiloid casts

Rafinesquina brachiopods

Cryptolithus trilobite cephalons

I think the fossil in the lower right is a Prasopora bryozoan

A cluster of what appears to be Dalmanella brachiopods

I think this is the underside of the very front most portion from an Isotelus cephalon.

Another unknown Trilobite bit

Another Bryozoan that is shown in cross section due to the way the rock broke.

The fossils above represent the material I picked up during a short visit to the roadcut along US 322 shown in the above photos. I didn't have a bag with me since I didn't expect to find anything so these are what I was able to carry in my arms and pockets. I'll likely visit this site again in the future.