End Triassic Extinction Event in the Hartford Basin, CT

[Paul1719]

For the last 15 years most of our fossil collecting has been in the Devonian and more recently in the late Devonian (Famennian). Interestingly, This represents a period between two episodes of the Devonian mass extinction, the end Frasnian Kellwasser event and the end Famennian Hangenberg event. The first was mostly marine and saw the end of most of the jawless fish but the second ended the reign of the Placoderms and a lot of dominant taxa of sarcopterygians including the Tristichopterids (like Hyneria). Most of the sites are chuck full of these guys. When I retired and decided to move, it was to the Hartford Basin. Much of this area exposes one of the other of the big 5 mass extinctions, the end Triassic. This is what gave the dinosaurs their opening. Central Connecticut has a number of basaltic ridges running north-south. These formed as Pangea broke up but while they were forming a number of lakes were present in this rift valley. Some of these lakes have yielded thousands of beautifully preserved fish. You can certainly see some in Tim Jones's (Fossildude) collection. With his guidance back in 2015 we were able to locate one of the sites, Bluff Head, Guilford, CT. This was fully excavated back in the 1970"s by Nick McDonald but they took out so much material scraps were bound to be left and so here I present some pretty snarge nice scraps. The first is the most common fish they found, Redfieldius. It is a Paleoniscid ray fin (Actinopterygian). The thing I really like is these are very similar to the Devonian Paleoniscids except they are bigger and better preserved. 

 

This first Redfieldius specimen is nearly complete with most of the skull, only missing the tip of the snout. It has a dorsal and anal median fin and just a smidge of the pectoral fin. 

 

The next one is also a Redfieldius, actually two! This is the best preserved example of both a skull (upper left) and the body/fins although two different fish. Unfortunately, most of the snout is under that beautiful anal fin!

 

Final example I'll show is also a Paleoniscid called Ptycholepis. It was found last year when I asked my son if he wanted to go hiking and he said why don't we go see if we can find the Bluff head site again. We really did not expect to find anything but this was the only fossil we found. The body is very worn as it has been exposed for maybe 50 years? but the skull was protected by matrix which needed to be carefully removed. To our surprise the entire skull was there. 

 

[Notidanodon]

Very cool fossils! I’m moving to Connecticut soon do you know if any of the sites where the fish can be found are still around?  

[Misha]

Beautiful fish! Especially that last one is a fantastic find

Even though I'm not usually interested in fossils outside the Paleozoic, the local Jurassic fish here in CT are super cool 

[Pagurus]

   Wonderful!  Your Redfieldius with the skull is terrific, Paul, and that Ptycholepis leaves me speechless. I was fortunate to find some very nice partial Redfieldius but only a few scales and small bits of Ptycholepis, a number of years ago.   I painted this Redfieldius a couple of years ago as a gift.

 

Mike

 

[Tidgy's Dad]

Lovely fish.

[Fossildude19]

Great rare fossils, Paul!

I don't think I've seen another Ptycholepis marshi skull as good as yours.

Well done!

[Jeffrey P]

Very nice Early Jurassic CT fish, Paul. That Ptycholepsis partial body and complete skull was a really neat find.  Congrats. Wish there were more Mesozoic sites in the CT Valley to check out. 

[Paul1719]

Thanks Everyone!!! I wish there were more sites. This site yielded something like 10,000? specimens back in the 70's!! Not sure where they went, Yale? I know McDonald made a big donation to PRI but not sure which? Tim? We recently took another trip there and ….found nothing! Not a scale nor stuff!

The original explanation for this was a storm but I wonder if it doesn't have something to do with the volcanism occurring here at this time. The best preserved fish are all in a very small geographic area in Guilford-Durham-N. Branford. There are other sites in CT that are suppose to have fish but quality is likely to be much less. Further up the CT river valley  in MA there are other amazing and inaccessible sites as well. 

[Fossildude19]

12 minutes ago, Paul1719 said:

Thanks Everyone!!! I wish there were more sites. This site yielded something like 10,000? specimens back in the 70's!! Not sure where they went, Yale? I know McDonald made a big donation to PRI but not sure which? Tim? We recently took another trip there and ….found nothing! Not a scale nor stuff!

The original explanation for this was a storm but I wonder if it doesn't have something to do with the volcanism occurring here at this time. The best preserved fish are all in a very small geographic area in Guilford-Durham-N. Branford. There are other sites in CT that are suppose to have fish but quality is likely to be much less. Further up the CT river valley  in MA there are other amazing and inaccessible sites as well. 

 

 

The running theory about the fish kills are storms that stirred up the toxic gas (hydrogen sulfide - similar to modern day African Lake Tanganyika) at the bottom of the lake, and killed off the fish, at different intervals.  Vulcanism could possibly cause similar events, I'd wager.

 

Can confirm quality of fish preservation elsewhere in the CT River Valley is not quite as good as the areas mentioned.

 

[Paul1719]

The exceptions being in Sunderland and Turners Falls, MA. Those are also exceptional preservation. The Sunderland site is on private land behind the house of a cranky old man (maybe not without reason)  and the Turners Falls site is about 1/2 way up a cliff on the CT river.

So one fish we don't have but I know Tim has some amazing examples of is the Holostean, Semionotus. Ian was able to find another example of a Holostean right down the street from us on the CT river! One of the only living representative of that taxon, Amia (Bowfin)!

 

[Fossildude19]

Here are some Semionotus examples:

 

[Andúril Flame of the West]

Those are some exquisite specimens @Paul1719 and @Fossildude19! I love seeing the beautifully preserved Newark specimens from up in New England given there near absence down here in the south. I barely have words for those Ptycholepis, Redfieldius, and Semionotus. 

 

Though the fossils are breathtaking, I must admit that the greatest surprise was seeing that nice bowfin. I wasn't aware that their range extended to the east coast - at least not in the present day. I suppose I'll have to keep an eye out next time I hit the water...

[jpc]

love these New England fishes.  Great work guys.

 

[Paul1719]

11 hours ago, Andúril Flame of the West said:

Those are some exquisite specimens @Paul1719 and @Fossildude19! I love seeing the beautifully preserved Newark specimens from up in New England given there near absence down here in the south. I barely have words for those Ptycholepis, Redfieldius, and Semionotus. 

 

Though the fossils are breathtaking, I must admit that the greatest surprise was seeing that nice bowfin. I wasn't aware that their range extended to the east coast - at least not in the present day. I suppose I'll have to keep an eye out next time I hit the water...

I thought the bowfin were really rare but when I moved here 4 years ago, I read some posts about catching them near here, on the CT river close to where my son caught that one. He also spoke with a guy who said they're not totally uncommon. Gars the other Holostean are in the order Semionotiformes. 

[Paul1719]

Here is a really interesting article by Bruce Cornet and Paul Olsen on the significance of the Hartford Basin in the End Triassic Event (ETE) and early Jurassic recovery. Bluff Head site seems to be dated to 50,000 years after! Anyone who has driven through central CT has witnessed the layers of basalt and rift valley terrestrial deposits here across the ETE.

Bluff_Head_fishupdatedAppendix2021.pdf

[Fossildude19]

Paul,

Have you ever found any bits of the coelacanth, ... Diplurus longicaudatus?

It is the only other fish found there, that hasn't been mentioned.

They are the most rare fish found in the Early Jurassic sediments of Connecticut.

 

Order of rarity:

1) Common - Redfieldius gracilis

2) Less Common (but still relatively common) - Semionotus sp.

3) Rare - Ptycholepis marshi

4) Super Rare - Diplurus longicaudatus

 

 

 

Single scale of Diplurus:

 

 

Partial specimen:

 

 

 

 

They are more widely known by their numerous coprolites.

Here is an example, with scale inclusions.