fossilzz Posted December 22, 2019 Share Posted December 22, 2019 I was wondering if a complete or fairly complete placoderm skull/head has ever been found at Arkona? I am just curious as what this would look like, and because I have a few placoderm bits and pieces myself, pictures of such a fossil could possibly help me to figure out where these pieces came from. (This is mostly out of curiosity though because I know small placoderm bits are basically impossible to identify) Link to comment Share on other sites More sharing options...
fossil_sea_urchin Posted December 22, 2019 Share Posted December 22, 2019 I couldn't find anything but this that might resemble a placoderm from there Sorry about the photo quality. I found it by searching "Arkona placoderm skull" and hopefully the images on the web are better. 1 Link to comment Share on other sites More sharing options...
fossilzz Posted December 23, 2019 Author Share Posted December 23, 2019 Thanks! This appears to have traditional teeth though, so maybe not a placoderm? I guess its not impossible though because I have no other examples to compare to. Link to comment Share on other sites More sharing options...
Kane Posted December 23, 2019 Share Posted December 23, 2019 Generally, the most commonly encountered placoderm to be found at Arkona is the arthrodire, Protitanichthys sp. (cf. rockportensis). Of course, that assignment is a bit of a waste-basket for what may be a number of more distinct species, but there is current research activity to better describe these. That being said, the body plan should be fairly similar to this genus. Some images to get your footing. A jaw from Protitanichthys (image from FossiiliD) Head shield (image from Stack, J., and Sallan, L. (2018). An examination of the Devonian fishes of Michigan. PeerJ. 6. e5636.): A photo of the assembled posterior median dorsal plate I collected last year from the Arkona area: - 8 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
fossilzz Posted December 23, 2019 Author Share Posted December 23, 2019 2 hours ago, Kane said: Generally, the most commonly encountered placoderm to be found at Arkona is the arthrodire, Protitanichthys sp. (cf. rockportensis). Of course, that assignment is a bit of a waste-basket for what may be a number of more distinct species, but there is current research activity to better describe these. That being said, the body plan should be fairly similar to this genus. Some images to get your footing. A jaw from Protitanichthys (image from FossiiliD) Thanks, The jaw is also very interesting, I didn't realize they had those toothy projections. Also nice find, that plate looks nearly complete! Link to comment Share on other sites More sharing options...
Northern Sharks Posted December 23, 2019 Share Posted December 23, 2019 Isolated teeth from a different placoderm are also sometimes found 6 There's no limit to what you can accomplish when you're supposed to be doing something else Link to comment Share on other sites More sharing options...
fossilzz Posted December 23, 2019 Author Share Posted December 23, 2019 15 minutes ago, Northern Sharks said: Isolated teeth from a different placoderm are also sometimes found That's really cool, I did not know placoderms had teeth! Link to comment Share on other sites More sharing options...
minnbuckeye Posted December 23, 2019 Share Posted December 23, 2019 54 minutes ago, Northern Sharks said: 4 hours ago, Kane said: 54 minutes ago, Northern Sharks said: I have found a few placoderm teeth similar to @Northern Sharks. But mine as well as his do not seem to look like the teeth embedded in the jaw. Am I mistaken, or is there quite a bit of variation to the look of placoderm teeth. On northern Shark's example, I always thought the base/ root of the tooth would have been below and the chewing surface along the 23 mm line based solely on how my teeth prep out and an ignorant prepper. But the jaw example looks as if the root is left and the tip (broken) is right. Silly question!! Mike Link to comment Share on other sites More sharing options...
Northern Sharks Posted December 23, 2019 Share Posted December 23, 2019 On my tooth, I believe the chewing surface (not that they chewed) is exposed and the root is still mainly in the matrix. It is a long, flat crushing tooth similar to a hybodont shark. The teeth shown in the jaw are a different genus altogether. There's no limit to what you can accomplish when you're supposed to be doing something else Link to comment Share on other sites More sharing options...
minnbuckeye Posted December 24, 2019 Share Posted December 24, 2019 19 hours ago, Northern Sharks said: On my tooth, I believe the chewing surface (not that they chewed) is exposed and the root is still mainly in the matrix. It is a long, flat crushing tooth similar to a hybodont shark. The teeth shown in the jaw are a different genus altogether. @Northern Sharks, Thanks!!!!! Now I will return to my original line of thinking. Mike Link to comment Share on other sites More sharing options...
Ruger9a Posted December 24, 2019 Share Posted December 24, 2019 Great specimen....would love one for my collection. Gotta go, I need to write another letter to Santa. Link to comment Share on other sites More sharing options...
BenWorrell Posted April 19, 2020 Share Posted April 19, 2020 On 12/23/2019 at 4:43 AM, Kane said: Generally, the most commonly encountered placoderm to be found at Arkona is the arthrodire, Protitanichthys sp. (cf. rockportensis). Of course, that assignment is a bit of a waste-basket for what may be a number of more distinct species, but there is current research activity to better describe these. That being said, the body plan should be fairly similar to this genus. Kane, Who is researching the Protitanichthys? Is it Stack and Sallan that you cited above? I found a placoderm plate last year in Eastern Iowa that I believe is some type of Protitanichthys, and I'm always trying to get more specific ID's. Thanks, Ben Worrell Link to comment Share on other sites More sharing options...
Kane Posted April 19, 2020 Share Posted April 19, 2020 8 hours ago, BenWorrell said: Kane, Who is researching the Protitanichthys? Is it Stack and Sallan that you cited above? I found a placoderm plate last year in Eastern Iowa that I believe is some type of Protitanichthys, and I'm always trying to get more specific ID's. Thanks, Ben Worrell I only know of one person currently studying them, although I don't want to put the name out publicly without permission, and it is not Stack nor Sallan. It reminds me that I need to get back in touch with that person, though! ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
crinus Posted April 20, 2020 Share Posted April 20, 2020 FYI One complete skull of a placoderm has been found in the Arkona formation. It is not mine so I am not at liberty to post a picture of it. joe Link to comment Share on other sites More sharing options...
Blastoid Posted March 15, 2021 Share Posted March 15, 2021 Make that at least two. One resides in Michigan, collected long ago, one more recently. From the Arkona Shale. Link to comment Share on other sites More sharing options...
Phevo Posted March 15, 2021 Share Posted March 15, 2021 On 12/23/2019 at 9:11 AM, Northern Sharks said: Isolated teeth from a different placoderm are also sometimes found That's great, I have a few isolated pieces like that I was uncertain what were so this helped a lot Link to comment Share on other sites More sharing options...
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