Tetrapod Footprints of Maryland

[EMP]

I've finally got around to compiling some photos of my tetrapod footprints from a road cut here in Maryland. All of these finds come from the early Mississippian aged Purslane Formation, which belongs to the Pocono Group and thus are about 350 million years old. In Maryland the Purslane represents the late Tournaisian through the Visean stages of the Mississippian.  These finds are particularly interesting because they come from an era known as Romer's Gap, which was a span of time from the end of the Devonian to the end of the Mississippian where worldwide fossils of tetrapods are rare, and known mostly from a just a few sites in the entire world. As far as I know no tetrapods have been recorded in rocks older than the Mauch Chunk Formation, which is the unit that overlies the Purslane in Maryland (in WV there is the added Hedges Shale above the Purslane, but this unit is absent in Maryland) so definitely some cool finds!

 

I've found what looks to be around two or three different kinds of tracks, some having rounded toes and others having pointer ones. I don't think they're new species, but rather new occurrences of younger species represented in the Mauch Chunk. Most of these footprints are hard to see without a certain angle of light, which unfortunately would obscure most of them in shadows. As such, I've resorted to outlining the shape of the prints in red.

 

Thanks to mstimson for giving me helpful information about them!

 

 

[EMP]

First is natural, next is the footprint in red. There's a second print on the outer edge of the rock just below the orange blob (it has four toes and a small "palm" preserved).

[EMP]

[EMP]

Natural and then circled in red. Two prints on this one.

[EMP]

Natural and then in red.

[doushantuo]

very very good finds,and important too

 

rogatrapod.pdf

[EMP]

Natural and again in red.

 

 

 

[EMP]

Natural and in red.

 

 

 

[doushantuo]

UKscotlviseannif-7.pdf

[EMP]

Natural and red.

 

 

 

 

[EMP]

10 minutes ago, doushantuo said:

very very good finds,and important too

 

Thanks!

 

As far as I know these are the first from the state, the formation, and the geologic group so definitely pretty cool. I doubt these are the only ones though, seeing as though there hasn't ever been a study on the fauna of the Pocono Group and the last paleontological "study" was back in the 80s when people were analyzing the potential of coal mining in the Rockwell and Purslane Formations. My guess is that no one ever looked before or were too concentrated on the sandstone layers above and below the shale ones where these come from.

 

 

[Ropterus]

Great finds! Definitely need a good eye and to know what you are looking for to see those! Congrats!

[Fossildude19]

Very cool stuff. 

Impressive.

Regards, 

[Jeffrey P]

VERY INTERESTING! Thanks for sharing your discoveries with us.

[EMP]

This is a pretty nice little piece I found today.

 

It shows a small footprint (clearly)  in the front to the right of a another, more poorly preserved one (this angle doesn't show the contours as well). I don't know if they're from the same animal or not.

 

What's even more interesting are all the other ichnofosils on this tiny piece of shale. Some of these thin lines may possibly be marks from the toes/claws of other tetrapods, however a couple of large burrows are also present.

[TNCollector]

These are interesting indeed, but honestly I don't know how you can distinguish these as being footprints as opposed to coincidental patterns of invertebrate ichnofossils. To identify an ichnofossil as a footprint in a location where they have never been found, you really need a series of them in a track. But that is just my opinion, you may be onto something important.

[jpc]

6 minutes ago, TNCollector said:

These are interesting indeed, but honestly I don't know how you can distinguish these as being footprints as opposed to coincidental patterns of invertebrate ichnofossils. To identify an ichnofossil as a footprint in a location where they have never been found, you really need a series of them in a track. But that is just my opinion, you may be onto something important.

I am with TNC on these.  I will admit to being a track skeptic if they are not obvious.  A trackway is what I need to see.

[doushantuo]

Agreed:indeterminate scratches do not an ichnite make

[EMP]

Here are the prints outlined in red:

 

 

11 hours ago, TNCollector said:

These are interesting indeed, but honestly I don't know how you can distinguish these as being footprints as opposed to coincidental patterns of invertebrate ichnofossils. To identify an ichnofossil as a footprint in a location where they have never been found, you really need a series of them in a track. But that is just my opinion, you may be onto something important.

 

Well, it is a bit easier to see it in person, I won't lie, and it usually takes a certain angle of light. 

 

But to differentiate between a footprint and other ichnofossils it usually would take a few things. First off, if there are multiple in a row, which unfortunately there aren't in this case, then it is most likely a footprint. Otherwise it depends on the structure. A footprint would usually have a structure of a footprint, that is it has toes and a manus area that occur in a pattern unlike what one would see from simple arthropod trackways or burrows. Going on, burrows are usually pretty distinguishable due to their larger size and more "tube" shape (often preserved in 3D). Arthropod trackways, especially ones by millipede like animals, are harder to distinguish from other ichnofossils, but again it has to do with what they look like. A millipede won't leave five tracks in one spot, jump an inch or so, and leave two or three more. Rather, it would usually be a continuous line, often with a segment of line showing where the body had been dragging (the ground isn't flat). 

 

[Fossildude19]

Any chance of getting the images posted directly on the Forum?

 

 

[EMP]

5 minutes ago, Fossildude19 said:

Any chance of getting the images posted directly on the Forum?

 

 

 

Here ya go. 

[doushantuo]

er,this'll prolly annoy you a teensy,but i STILL don't see an ichnite there

[TNCollector]

I don't see anything conclusive either. There are so many ichnofossils scattered on those rocks that there are certainly many of them overlain on top of each other that can make a "footprint"-like shape. Don't get me wrong here, I am not saying that these are not footprints, I am just saying that in light of the fact that footprints have never been documented from this area, Early Mississippian footprints in the USA are generally quite rare, and there are no trackways, I don't think that you can definitively say that these are footprints. If you really feel like they are, keep going collecting at this site and look for a trackway. If you find one, then your claims will hold more substance.

[Plax]

I recall hearing about a Mississippian trackway site SE of Pottsville PA off 61 but never checked it out. It's in the lit so you may be able to google it.