A Brief Hiatus

I apologize for the hiccup in my regular posting schedule but between a short vacation and my old computer giving out, I've not had the time to write more entries. Rest assured I will be back on schedule shortly and will have plenty of fossil coolness to talk about. Thanks for your patience. - Dave

Cleoniceras

Hailing from the island nation of Madagascar is this cut and polished Cleoniceras Ammonite. The creature which once inhabited this shell died about 105 million years ago during the Albian stage of the lower Cretaceous. Note the pearlescent exterior of the shell and the hollow interior of the chambers. This specimen was not terribly expensive and the fossils are extremely common at many fossil dealers tables or websites.





I liked this specimen because of the exterior shell being intact. Some specimens are ground and polished so that you can see the suture lines of the chambers where they met the exterior shell. It also clearly displays the typical growth pattern of coiled Cephalopods with a spiral of previously occupied chambers winding back to the beginning of the creatures life. I wonder how often the animal would pull it's body forward and seal off another section of it's shell to be used for buoyancy? I can count more than sixty chambers but there are probably more that I can't discern because they are too small. If they made a new chamber every month then this animal would be at least five years old, but this is only speculation.

Leiorhynchus rockymontanum

Leiorhynchus rockymontanum is a somewhat strange looking brachiopod. It takes the Rhyconellid body habits of a central sulcus to extreme limits. AS you can see from the pictures below the body does not have much actual depth to it, in fact it's somewhat flat. However, the shape of the central sulcus bends the body out of shape. This and the next specimen are both from the Finis Shale of Jacksboro, Texas and hail from the Carboniferous period (Pennsylvanain).







Specimen #2

Juresania

Continuing with the theme of late Carboniferous/Permian Brachiopods here is Juresania. A member of the Productida order, Juresania has the typical domed Pedicle valve and flattened Brachial valve. One of the key features are the regular short spines that line the shell (another hallmark of the Productida order).








Both the above specimen and the next specimen come from the Carboniferous (Pennsylvanian) aged Finis Shale near Jacksboro, TX.

Gastropods from the Texas Carboniferous

I purchased a lot of specimens from a member of the Fossil Forum recently that were from the Cretaceous and upper Carboniferous (Pennsylvanian) of Texas. All the fossils had been personally collected by Dan Woehr and you can read about his trips at his "Meanderings of a Texas Fossil Hunter" website. You've seen some of the Brachiopod specimens from the Finis Shale that I have acquired from Estate sales but today I wanted to illustrate some of the common Gastropods that Dan sent me.

Glabrocingulum grayvillense







Worthenia tabulata








Straparollus sp. Note that one side of the shell is flat while the other is raised. This indicates to me that the snail dragged the shell across the bottom rather than having it hoisted above it's body as most snails do.






Euphemites nodocarinatus








Pharkodonotus percarinatus








There are those who say that you should never buy a fossil that you could collect yourself. While this has some merit, my prime motivation for purchasing these fossils from Dan is two fold. First, these make good study fossils for me to compare to those I might find in other areas (including here in Pennsylvania). Second, who knows when I will be able to get down to Texas to do my own collecting and if I would have the opportunity to collect all of the above species during a trip. If I purchase fossils I like to do so from the same people who found and collected the specimens. This way I have a knowledgeable local person whom I can ask questions about the fossils and I know they are taking the time and effort to make sure the specimens are correctly labeled and carefully packed. Support your local fossil collectors!

Conulariida

Conularid fossils are something of a mystery for Paleontologists because they don't seem to fit into any one particular Phylum well. Recently it's been proposed that they are a type of scyphozoan cnidarian (jelly fish). One theory has them floating in the water column and snagging passing prey while others assert a more sedentary lifestyle attached to the substrate. They are known from the Cambrian through the Triassic but I've only ever found them in Ordovician rocks north of Frankfort, Kentucky.

Here is one that my friend Mike over at Louisville Fossils sent me. It's from the Borden Formation in Jefferson County which is Mississippian in age. Note the fine ribs along the sides and the square cross section.





This specimen is from the Carboniferous (Pennsylvanian) Finis Shale near Jacksboro, Texas. Note that this fossil doesn't have the square cross section like the above specimen, rather it is more oval shaped. EDIT - This fossil is not a Conulariid but is actually a Pelecypod called Aviculopinna. I should have picked up on that myself due to the shape of the fossil but sometimes I get fooled by a label.