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Showing results for tags 'chondrichthyan'.
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This week, I took the time to break open the 6 chunks of matrix I had brought home from the Mississippian Burlington Limestone from a trip this Fall. My finds were not as good as other trips but it is always exciting to see what pops out of these rocks. My identifications are going to be educated guesses at best. I am not versed very well in Chondrichthyan recognition. The pictures 1,2 and 3 look like teeth but I can not find images that fit their looks. Could they be dermal appendages??
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- burlington fish layer
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Back in 2020 I went with a university paleontology class to a quarry in Alabama where the Mississippian Bangor Formation is exposed. Much of the formation is massive pure limestone, which is used for cement production. However at the top of the quarry there are thin limestone layers separated by shale. As this is unsuitable for cement, it is stripped off and discarded adjacent to the quarry, and we are allowed to search this. Crinoids and blastoids are common finds, and other fossils including chondrichthyans ("shark" teeth and spines) are found occasionally. On the 2020 trip I found a partial large edrioasteroid, the first the professor had seen and they had been leading trips to the quarry for many years. (BTW edrioasteroids are known from other Bangor exposures, just not this quarry). Last weekend I was trimming up some fossils with a tile saw to make space in the cabinet. The edrioasteroid was still on a fairly big slab partly wrapped in aluminum foil. The back had a centimeter or so layer of dried mud and broken down shale covering it. Before I started to cut up the slab I decided to clean off the back, in part to make cutting less messy, and also just to make sure there wasn't anything interesting on that side. In the past I have cut right through good fossils because I didn't know that they were there. As I took a toothbrush to the mud and broken down shale, a bit of black appeared. This was interesting, as about the only thing in these rocks that is black are the fish teeth. A bit more scrubbing, and a beautiful Chomatodus tooth appeared, the best I have seen personally. There is a small bit (maybe ~2 mm) missing on one end, but otherwise it's all there and perfectly exposed. The taxonomy of these fish is quite confused, and even experts are declining to put species names on specimens until the genus is properly revised, so I am labeling this specimen as Chomatodus sp. Just for fun, I will be entering this one for Fossil of the Month. The edrioasteroid (Hypsiclavus huntsvillensis): The tooth (Chomatodus sp):
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- alabama
- bangor formation
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Two days ago I went with @Tales From the Shale and another friend on a fossil hunting trip to a Bond Formation Roadcut in Oglesby, Illinois with rocks dating around 307-303 Million years ago, to the Pennsylvanian section of the Carboniferous era. Hadn't been back to the site since October 2022 and it was good to be back! I was pleasantly surprised at the lack of snow. But it was clear it only melted very recently judging by the arm sized icicles and the mud. (Quick advice for anyone planning to go fossil hunting at this time in Oglesby: bring snow boots to balance yourself on the rocks and mud, they will be a life saver). Found the usual brachiopods and crinoid bits at first, but then I found a 5cm long crinoid stem (the most intact one I've found so far from the area). I don't know currently what species it belongs to. We worked for two hours at the site before heading to another site in Braceville before heading back to Chicago. Today, I looked at some of the specimens I found and realized I found a lot more than I initially expected. Definitely enjoyed finding the large brachiopods (the second one I believe is a large Linoproductus). Found some Bryozoan (species unknown), the first I've discovered in Oglesby. Found a small but still pretty cool Cladodont shark tooth around 1-2cm in length. Currently don't know the species yet. Another cool Brachiopod (I think it's a Punctospirifer species). Also found some Petalodus teeth, Trilobite pieces, and bits of Peripristis. I'll post those and more detailed images of the others when I have access to my college's microscopes later this week.
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- bond formation
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Was the Early Miocene a second "golden age" for the Chondrichthyans
Joseph Fossil posted a topic in General Fossil Discussion
I recall not too long ago there was a pretty interesting scientific article published in the Journal Science describing how scientists analyzed the amount and diversity of chondrichthyan denticles in ichthyoliths from the North and South Pacific dating from around 20-19 million years ago and discovered a sharp drop in the number and diversity of denticles around 19 million years ago, indicating a massive extinction took place which took sharks 2 to 5 million years to somewhat recover from (it's still unknown if this impacted chondrichthyans worldwide or just in the pacific). Here's the paper: https://www.science.org/doi/10.1126/science.aaz3549 E. C. Sibert, L. D. Rubin, An early Miocene extinction in pelagic sharks. Science 372, 1105–1107 (2021). But after reading it, I remembered how the Mississippian and somewhat Pennsylvanian periods of the Carboniferous era have been called the golden age of sharks due to the sheer diversity of chondrichthyan genera alive at that time. http://www.elasmo-research.org/education/evolution/golden_age.htm What I'm wondering is does this paper, in revealing this early miocene extinction event, inadvertently also reveal that the period immediately prior to the event was a second "golden age" for the chondrichthyans?- 19 replies
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- carboniferous
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Help identifying possible organisms from nodules of Pit 11, Mazon Creek
Joseph Fossil posted a topic in Fossil ID
Starting in 2021, I've been going fossil hunting around the Mazon Creek area in Grundy County, Illinois. The site I visit the most so far is the fairly large Mazonia-Braidwood State Fish and Wildlife Area and at first, I would barley find anything. Then after visiting Monster Lake and another secret location in the area, I started finding more fossils. However, most are around 2-7 cm. In length and I'm still having difficulty getting IDs for them? Would anyone be able to help ID them? I think this could be some sort of Chondrichthyan or a lobe finned fish? Maybe part of a dragonfly wing or a plant? Plant fossil - Genera unknown currently? I don't know what this could be? The specimen here looks almost like a plant fossil. Worm fossil - genera unknown currently.
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What caused the decline of the Eugeneodontids - (Buzz saw sharks)
Joseph Fossil posted a topic in Questions & Answers
I've been fascinated with the Eugeneodontids (the buzz-saw chondrichthyans) and how they managed to practically become the apex predators of most oceanic environments from the Carboniferous to the Permian with famous members like Edestus and Helicoprion. Two genus of this extraordinary group even survived the Permian-Triassic Extinction 252 Million Years ago - Fadenia and Caseodus! http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34456 http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34451 But by the Olenekian stage of the Triassic, the group disappeared. I can understand why the more specialized members of the group like Helicoprion went extinct (ecological specialists and top predators don't do well in events like the Permian-Traissic Extinction event), but what caused the extinction of Fadenia and Caseodus? What occurred in the Triassic that ended the reign of the Eugeneodontids? -
Hi! Me and @Tales From the Shale are actively thinking of going on a fossil hunting trip in Alton Illinois (right by St. Louis, Missouri) this week to analyze the Mississippian period St. Louis limestone and I'm wondering if anyone else has gone down there? https://www.mindat.org/feature-4232679.html We're specifically looking for fossils of the Meramac group and though we have a quarry or two, we're thinking of also checking out any road cuts in the area. I'm wondering before we go on the fossil hunt (likely this Saturday), could anyone offer some info on any good road cuts in the Alton area as well as quarries and if there are also a descent amount of fossils in the Spergen limestone too?
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On Saturday I went fossil hunting with @Tales From the Shale in Utica, LaSalle County, Illinois! We drove for some time looking for roadcuts when we discovered an abandoned clay pit not too far away from the town itself. I learned later its rocks date to the Pennsylvanian period of the Carboniferous era. There were also a bunch of nodules there too, but mostly it was stark shale and Excello shale. We opened the shale rocks up and we found a massive amount of small fossil imprints. But we also found some likely Chondrichthyan spines which I was wondering if anyone could ID the genera? This first specimen I found after breaking open a large piece of Stark Shale. I asked @Tales From the Shale for an ID and he said it very likely a Listracanthus spine. Here is the specimen under a dissecting scope!!! The striations typically seen on chondrichthyans like Listracanthus or Cladodus are more visible here, but I'm a bit unsure if these could be matched to either of these genera?
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A few days ago, I went with @Tales From the Shale and another friend on a fossil hunting trip to a Bond Formation Roadcut in Oglesby, Illinois with rocks dating around 307-303 Million years ago, to the Pennsylvanian section of the Carboniferous era. We worked for at least 5 to 6 hours, but it was worth it! This was one of the best fossil hauls I've had in a long time at that location! The true gem of that trip was this Cladodont tooth I discovered by sheer accident!!! The specimen may come from the Shark Gilkmanius, but I'm not too sure? The top part of the tooth might still be inside the rock. I found some of the largest crinoid stems I've ever recovered from this locality. Again, I'm not sure their genus identity?
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- bond formation
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Recently I went on a fossil hunting trip with a few friends to a roadcut in Oglesby Illinois from the Pennsylvanian Bond Formation. This was around July and I found a lot of cool Brachiopod fossils, but I decided a few days ago I wanted to get a closer look at some of the larger matrixes I collected to see if I missed something! At the very edge of one the matrixes, I discovered a small pretty exposed cladodont tooth that I couldn't find a specific ID of? The specimen is about 1/2 inch in length (5.0 mm.). But I wanted to see it a bit closer, so I put it under a microscope one of my college professors let me borrow. The specimen has a pretty slender shape overall and the top of the medial cusp appears to be broken off. I compared the specimen to other ctenacanthiformes from the Bond like Heslerodus and Gilkmanius. It does resemble Gilkmanius a bit, but I looked further and have drawn a slightly different conclusion - this could be a specimen of a juvenile Saviodus striatus. https://www.uky.edu/KGS/fossils/fossil-of-the-month_2022-07_Saivodus.php Like Saivodus, the Medial cusp is incredible slender for what's left of it. The Laterial cusps and cusplets on Saivodus teeth are much smaller compared to the Medial cusp than those of Heslerodus and Gilkmanius. On the microscope image, you can just barley make out a small cusplet next to the Medial cusp and a small Lateral cusp on the left side of the image (since under a microscope, it's actually on the right side of the tooth). Still, I'm not 100% sure my ID is correct. I was wondering if anyone is able properly ID this specimen? I'm also wondering if this cladodont tooth is indeed a specimen of Saivodus striatus or another member of the genus (which I would be awesome) or a a member of different Ctenacanthiform genus (which also would be awesome)?
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Fish got their jaws millions of years earlier than previously thought Meet the spiny, ancient Fanjingshania renovatais—likely the oldest discovered fish ancestor with jaws. Laura Baias, Live Science Ancient 'shark' from China is humans’ oldest jawed ancestor Palaeontologists discover a 439-million-year-old 'shark' that forces us to rethink the timeline of vertebrate evolution Chinese Academy of Sciences, Eureka Alert, October 3, 2022 The paper is: Andreev, P.S., Sansom, I.J., Li, Q., Zhao, W., Wang, J., Wang, C.C., Peng, L., Jia, L., Qiao, T. and Zhu, M., 2022. Spiny chondrichthyan from the lower Silurian of South China. Nature, 609(7929), pp.969-974. Yours, Paul H.
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- cartilaginous fishes
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I am in the process of identifying the Chondrichthyan teeth that I have been extracting from Burlington Limestone collected this summer. Here are my most confusing teeth that hopefully can receive identification from our forum experts. 1. 2. 3. Possibly a dermal denticle instead of a tooth? 4. 5 .
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- burlington formation
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From the album: Harding Sandstone
Chondrichthyan? denticles Tezakia hardingensis Harding Sandstone, Canyon City, CO, USA These are possible Ordovician Chrondrichthyan (class of cartilaginous fish including sharks) denticles, if true, these would be the earliest known. Described by Andreev et al. (2015) and Sansom et al. (1996) ^Andreev et al. (2015) -
I was working through some Burlington Limestone, Mississippian looking for the Chondrichthyan fossils found within. Most primitive shark teeth in this matrix are fairly small, which is why this unknown surprised me when discovered. My suspicion is Deltodus except for the massive size. I welcome all thoughts on this ID. Unfortunately the missing pieces were not found. @Elasmohunter, this one's for you!!!!!!!!!!
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- burlington
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Here are a few holocephalian teeth from the Pennsylvanian LaSalle Limestone from Illinois that I have been unable to ID. I find these teeth hard to ID since the tooth plates of a single species are often so varied in morphology, and I can rarely tell if I'm looking at a fragment or whole plate. Hopefully someone more experienced than I can tell. For the first tooth, I tooth a picture in situ before trying to split the boulder as I was afraid it would crack. Well it did unfortunately and I was only able to save a few pieces. This second tooth looks like Psammodus but I'd love a second opinion (or even a species identification if possible). And this third tooth looks like a fragment, but I really don't know. @Archie @deutscheben Let me know if you have any thoughts. Thanks.
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- chondrichthyan
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