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Fossil Hunting at the Red Hill Devonian Fossil Site: Early Fish Fin Spine

Red Hill Fossil Trip - Early Fish Fin Spine and a Hyneria Tooth With Feeding Damage

It's been a while since my last visit to the famous central Pennsylvanian Devonian fossil locality known as "Red Hill". This famous fossil location contains the remains of the two oldest tetrapods in the United States - Hynerpeton and Densignathus.

Although finding one of these early tetrapods is next to impossible, this place preserves a wonderful Devonian ecosystem that thrived in the muddy lakes and streams that ran down the Acadian Mountains.

Commonly found fossils are fragments of Placoderms (bizarre armored fish), Hyneria, huge lobe finned fish (fish with fins that look like feet), freshwater sharks, Acanthodians (very early jawed fish), and also many early plants.

On this fossil hunting trip, as with the previous ones to Red Hill, I was dead set on finding a nice fin spine from an enigmatic Acanthodian. The fossils here are very fragmentary, and it's difficult to find large intact fossils.
I climbed the roadcut and found a spot to excavate. The key here is to slowly carve out a large section of cliff then pry it out. That way if there is a large fossil in it, it would still be intact. After about an hour, I had a huge chunk pried out of the cliff. Carefully excavating it, i found nothing! Plan B was to do it all over again. This time the local Paleontologists, who runs the site, Doug Rowe pointed out a nice bone bed to try. After a few minutes, I discovered part of a large fin spine. The rest of the day was spent trying to dig into the cliff, exposing the spine without breaking it. I was fairly successful, as I ended up with about a 4" length of fin spine. Both ends are not present, but it's the largest complete section of a fin spine I found so far.

While I was doing this, Amy was searching the cliffs for fossils sticking out of the matrix (this method actually works well for Hynera teeth (large lobe finned fish). She ended up finding a nice one. I was called over to try to extract it. After carefully chiseling it out, I noticed the tip was broken. Perplexed, because I was way too careful to have broken the tip, I extracted it and wrapped it up for protection.

After getting home, I cleaned the tooth up and noticed the tip was actually sheered off in a couple different directions. This looked identical to sperm whale teeth with feeding damage. It clearly did not look like post fossilization breakage. My only explanation is the tooth bit into something very hard... twice... causing the damage. This is the first tooth we have found with apparent feeding damage.

Overall, this was a successful trip! We came back with a fin spine and an Hyneria tooth with feeding damage!

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If you are interested the transition from fins to feet and Tetrapod Evolution, I strongly suggest:

Gaining Ground, Second Edition: The Origin and Evolution of Tetrapods (Life of the Past)
by Jennifer A. Clack

This book, full of comparative illustrations and photos, tells the story of tetrapod evolution, how it started 370 some million years ago, and goes through the different interpretations of the various early tetrapods. It is a must for anyone interested in Tetrapod evolution. If you have ever fossil collected at Red Hill, this book puts everything in perspective.

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Below are pictures and fossils from the Devonian Red Hill fossil hunt:

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