Hyneria lindae tooth from the Catskill formation

Pennsylvania is fortunate to have some rocks that record a rich record of fish as they were starting to diversify.  There are a few well known exposures of the Catskill formation which will yield fossils of these early fishes and one of them is called Red Hill. I have been collecting at that site once as part of an organized field trip. The site is managed by local authorities and the Philadelphia Academy of Natural Sciences and limits the number of collectors who visit. The fossil below was found at the site but not by me. I purchased it as I was not lucky enough to find one for myself. It is a tooth from a fish called Hyneria lindae which was an lobe finned fish. Those were the fish that eventually went on to learn to crawl onto mudflats and became Amphibians and Reptiles. 

Hyneria lindae was a good sized fish with an estimated length of 10' in larger specimens. It was a top predator in it's ecosystem and the tooth below shows you why. It is a long tooth but missing the very tip. Were it a little wider and flatter you'd think it belonged to a shark, but as it is one could almost see it in a Crocodile or Theropod dinosaurs mouth. Suffice to say, it looks like a tooth that a predator would have.

I've posted a scale from this giant fish on a previous blog post.

Here is a great page from the Philadelphia Academy of Natural Sciences that shows some of the fossils of Hyneria lindae and talks about how an artist came up with a painting of this long extinct creature.

The rocks at Red Hill are Devonian in age (upper Famennian stage) at about 360 myo and belong to the Duncannon member of the Castskill formation.

Dinophyton spinosus Plant fossil from the Stockton formation

Dinophyton spinosus is an odd plant that is found in the late Triassic of rocks across the US. It's often found as a small branch or sprig of tiny rounded leaves. Paleontologists have been trying to figure out how it fits within the evolution of plants but have so far been frustrated. What research I have found (Source 1, Source 2, Source 3)says that it is a gymnosperm (it's seeds are not protected by a fruit) which puts it close to conifers, Ginko's and cycads. The specimens below come from the late Triassic aged Stockton formation near Phoenixville, PA. This is practically in my back yard and I'd never heard, let alone seen anything like these before. 

During the late Triassic, Southeastern PA was a rift zone as Pangea split up. The Stockton formation was deposited on a level plain during drier, savanna like conditions. It inter-tongues with the Lockatong formation which represents lake sediments that would wax and wane as the climate changed. The specimens below were probably preserved in small, temporary ponds.

Sample 1 - Just a small leaf cluster on this piece.

Sample 2 - This piece has a few more sprigs of Dinophyton spinosus.

Previously, I blogged about some Conchostracans that I found from the Lockatong formation.

The Stockton formation is dated to the Triassic, roughly Carnian stage. I purchased these fossils in 2018.

Rhynchosauroides sp. swim traces from the Newark Supergroup

Today I have a fossil trackway to show you. This is more properly called an Ichnofossil as the body of the animal is not present. On this piece of shale are what appear to be scratch marks. I lost the original tag that came with the specimen but I recall that they were traces from swimming. An inquiry to the Fossil Forum website and the hive mind came up with Rhynchosauroides sp. as the name of the traces.  These represent a primitive reptile that was swimming in a pond or pool near a river. The creature floated in the water but it was shallow enough that it's claws grazed the sediment below and left traces. The pond may have been temporary and subject to frequent flooding as the substrate was firm enough to preserve the initial traces before they washed away, and then get buried with a new layer of sediment.   As I mentioned before, I lost the original tag but I believe this was Triassic aged and came from the rocks of the Newark Supergroup in Pennsylvania.  These rocks were originally laid down in a rift valley as the super continent Pangea was breaking up.

Protoleptostrophia and Uncinulus? from the Mahantango formation of Pennsylvania

Up today are a couple of Brachiopod specimens that I collected recently from the Mahantango formation in central Pennsylvania. The first specimen is a mold of a flat valve with many thin, narrow radial ribs covering the surface. To me this looks like a specimen of Protoleptostrophia perplana because it is similar to specimens I have from the Silica Shale, and the Windom Shale which are both contemporaneous with the Mahantango formation (Devonian, Givetian stage). This specimen came from the Frame Shale member and was found in Seven Stars, PA.

Closer views of the shell show features like possible epibionts that were attached to the exterior surface and variations in the growth of the ribs (due to life events that damaged or otherwise cased growth to change)

The second brachiopod came from the Montebello mbr. north of Harrisburg, PA. It is a rynchonellid that looks very similar to the genera Uncinulus. It is rouned in the cross section and (seemingly) narrows to a point at the posterior. The problem is that there is not enough detail preserved on the anterior for me to see what the margin looks like. If it is a strong "U" shape then I would go with Unicinulus. If the margin is not as strongly shaped then it could be a variety of Camarotoechia.

Hash plate from the Mahantango formation of Pennsylvania

On a recent stop at one of my favorite Mahantango formation collecting spots, I came across this hash plate. It's presumably a record of a storm event which is why there is a diversity of fossil species and why they are jumbled together.

The stippled bar shape in this photo is likely a segment from the exoskeleton of the trilobite Dipleura. It is surrounded by impressions of a Spirifirid and some Chonetid brachiopods.

Here is the impression of a crinoid column segment. The five fold symmetry gives it away. I'm not sure what species it belonged to but it is nicely decorated. It appears that it was resting under a Chonetid type brachiopod shell but was exposed when I split the rock.

This is a fairly good impression of a Chonetid type brachiopod. By the size and shape I would lean towards Devonochoonetes coronatus but without the spines that line margin of the hinge line, I can't say for sure.

Lastly there is the impression of a pelecypod with some very fine, concentric growth lines.  I would venture a guess that this is Nucula sp. similar to Nucula bellistriata like this one from the Panther Mountain formation of New York.

The Mahantango formation is Devonian in age (Givetian stage) and the portion I was collecting from is roughly equivalent to the Panther Mountain formation of New York. The exposure was a borrow pit near Seven Stars, PA in Juniata County.

Three Pelecypods from the Mahantango formation of Pennsylvania

One site that I like to collect at is most easily accessible in the spring since the undergrowth has not yet leafed out. It's an old quarry, which exposes the Montebello sandstone member of the Mahantango formation, that is many decades abandoned and yet one can still find some neat fossils there with a little searching. These three pelecypod shells came from one such collecting trip in April.

Cornellites flabella - Can easily be identified by the strong radial ribs and high angle of the body of the shell to the wing.

This appears to be a Pseudaviculopectin sp. pelecypod. the impression is somewhat faint and shallow but does resemble this specimen from the Windom Shale of New York.

Note the worm tube epibionts that are scattered on the surface of the shell.

Lastly is a shell impression that is more interesting for the epibiont that grew on it than the shell itself.

When you look close you can see some sort of rambling "trail" that maybe represents a coral like Aulopora or a bryozoan of some kind. There is not enough detail preserved for me to tell for sure.

All three specimens were collected from the Montebello Sandstone member of the Mahantango formation (Devonian, Givetian stage). It is roughly equivalent to the Panther Mountain formation of New York.

Douvilina? from the Mahantango formation of Pennsylvania

Since the fossils preserved in the Mahantango formation are often just molds or casts of the original shell, it can be difficult sometimes to try and ID what you have found. The specimen below is something I really have to think about. The shape tells me its a Strophomenid type brachiopod. The faint radial ribs are very fine and resemble a genera called Douvillina (like this one from the Centerfield mbr. of the Ludlowville formation in New York). I'm fairly confident that this fossil is a Douvillina sp. but the small "dents" that are in the center rear portion of the shell make we wonder if this is an internal cast of the pedicle valve. If this were the case then the "dents" would correspond to raised portions on the interior of the shell like the cardinal muscle attachment points.

A couple of closer views taken with different angles of light to highlight some of the features.

Note that you can see the impressions of the hinge teeth along the back edge of the cast.

This specimen was collected from the Montebello Sandstone member of the Mahantango formation (Devonian, Givetian stage). It is roughly equivalent to the Panther Mountain formation of New York.

Sulcoretipora cf. S. incisurata bryozoan from the Mahantango formation

Sulcoretipora is a flat, branching bryozoan that is somewhat common in the Devonian. The specimen below comes from the Mahantango formation of central Pennsylvania, likely from Seven Stars or Deer Lake. I bought it at a fossil show due to the length of the fossil since, normally, I only find small sections of the skeleton that were broken off from the main colony by storms or otherwise redeposited. This specimen also has several smaller branches forking off from the main portion.

Based on the book "Stratigraphy and Paleontology of the Mahantango Formation in South-central Pennsylvania" by Robert L Ellison, Bulletin G48, Pennsylvania Geological Survey, 1965, I am calling this specimen Sulcoretipora cf. S. incisurata. Note, the use of cf. in this name indicates that the species is not known but is similar to specimens of Sulcoretipora incisurata known from other locations. It's short hand for the Latin word "confer" meaning "look at other sources".

I've blogged about some nice examples of Sulcoretipora deissi I found in the Silica Shale here. Sulcoretipora has a similar growth habit as Taeniopora exigua like in the specimens I blogged about here.

Mold of a large Bryozoan from the Mahantango Formation

This piece is a mystery to me as well as an uncommon fossil from the Mahantango Formation. It's a mold of a large, rambling Bryozoan colony. There is little detail preserved of the exterior save for the internal zooid molds. I have not been able to determine if there are any monticules present which could help with the ID.

I'm thinking this is some sort of Fistulioporid species of Bryozoan but I can't find anything in the literature that would give more of a clue to narrow down the species.

The above specimen was found near Seven Stars, PA in the Mahantango formation, Upper Shale member (Devonian, Givetian stage)

Giant Ancyrocrinus spinosus crinoid anchor from the Mahantango Formation

A recent trip to an exposure of the Mahantango Formation near Seven Stars, PA yielded this giant Ancyrocrinus spinosus anchor. It's still embedded in the rock but you can see four spikes emerge from the bulb like base.

This is by far the largest specimen of this genera that I have ever found and only the second that I've found in the Mahantango Formation. The total length of the exposed bulb and spikes is about 4cm.

I posted a few years ago about some small anchors I found in a different part of the Mahantango Formation in Montour County, PA Here and a specimen that I found in the Windom Shale along Lake Erie in NY Here.