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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.
Hey y'all, hope you're all having a good time! This recently published report by Hodnett & Elliott (2018) describes two fairly diverse chondrichthyan faunas from the late Mississippian/early Pennsylvanian of western Grand Canyon (Arizona). The assemblages, from 2 separate formations, are described on the basis of quite many tooth specimens, and other material (i.e. denticles). Differences between those faunas and other similar-aged Euro-American faunas indicate paleogeographical implications relating to the formation of Pangaea. Hodnett, J. P. M., & Elliott, D. K. (2018). Carboniferous chondrichthyan assemblages from the Surprise Canyon and Watahomigi formations (latest Mississippian–Early Pennsylvanian) of the western Grand Canyon, Northern Arizona. Journal of Paleontology, 92(S77), 1-33. Abstract: Two chondrichthyan assemblages of Late Mississippian/Early Pennsylvanian age are now recognized from the western Grand Canyon of northern Arizona. The latest Serpukhovian Surprise Canyon Formation has yielded thirty one taxa from teeth and dermal elements, which include members of the Phoebodontiformes, Symmoriiformes, Bransonelliformes, Ctenacanthiformes, Protacrodontoidea, Hybodontiformes, Neoselachii (Anachronistidae), Paraselachii (Gregoriidae, Deeberiidae, Orodontiformes, and Eugeneodontiformes), Petalodontiformes, and Holocephali. The euselachian grade taxa are remarkably diverse with four new taxa recognized here; the Protacrodontidae: Microklomax carrieae new genus new species and Novaculodus billingsleyi new genus new species, and the Anchronistidae: Cooleyella platera new species and Amaradontus santucii new genus new species. The Surprise Canyon assemblage also has the youngest occurrence of the elasmobranch Clairina, previously only known from the Upper Devonian. The Surprise Canyon Formation represents a nearshore fluvial infilling of karstic channels, followed by a shallow marine bioherm reef, and finally deeper open water deposition. The early Bashkirian Watahomigi Formation represents open marine deposition and contains only two taxa: a new xenacanthiform, Hokomata parva new genus new species, and the holocephalan Deltodus. The relationship between the Surprise Canyon and Watahomigi chondrichthyan assemblages and other significant coeval chondrichthyan assemblages suggests that there may have been eastern and western distinctions among the Euamerican assemblages during the Serpukhovian due to geographic separation by the formation of Pangea. Here's the paper Hodnett & Elliott 2018 Grand Canyon chondr. fauna.pdf Happy New Year to you all!! -Christian