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| Strigilodus tollesonae Hodnett, Toomey, Olson, Tweet & Santucci, 2023 Illustration by Benji Paysnoe nps.gov/MACA |
ABSTRACT
Isolated teeth of two janassid petalodonts collected from cave passages within the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky represents the first record of this group of chondrichthyans from this formation. A new janassid, Strigilodus tollesonae, gen et sp. nov., is recognised from isolated teeth, representing all tooth families, and are characterised by their rounded spoonlike cusps and V- to U-shaped lingual cristae. Janassa sp. is also present within the Joppa Member of the Ste. Genevieve Formation. Dental reconstructions are proposed for Strigilodus tollesonae and Cypripediodens cristatus, modelled after previous observations for Janassa dentitions. Strigilodus had a dental arrangement more similar to Janassa, while Cypripediodens was uniquely adapted for a possible extreme form of durophage feeding. We propose that within Janassidae, there were two unnamed subfamilies with Janassa and Strigilodus forming the Janassinae, while Cholodus, Cypripediodens, and Cavusodus forming Cholodinae subfam. nov.
KEYWORDS: Ste. Genevieve Formation, Mammoth Cave National Park, Mississippian, Carboniferous, petalodont, Janassidae, Chondrichthyes, Strigilodus, Janassa
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| The geographic and palaeogeographic position of Mammoth Cave National Park, Kentucky. (A) The geographic position of Mammoth Cave National Park, Kentucky. (B) The Middle Mississippian palaeogeographic position of the Mammoth Cave National Park within the Illinois Basin. |
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| Stratigraphic position of the Joppa Member (star) of the Ste. Genevieve Formation and the chondrichthyan assemblages of the Mississippian sequence at Mammoth Cave National Park, Kentucky. Major orders of chondrichthyans are colour coded: Symmoriiformes, lime green; Phoebodontiformes, yellow; Ctenacanthiformes, Orange, Euselachii, red; Paraselachii, green; Eugenodontiformes and Orodontiformes, light blue; Petalodontiformes, blue; Holocephali, purple. |
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| The proposed dental reconstruction of Strigilodus tollesonae gen et sp. nov. Abbreviations: SY/sy, symphyseal tooth; AL/al, anterolateral tooth; ML/ml, mediolateral tooth; DL/dl, distolateral tooth. |
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| Comparison of dental reconstructions of janassid (A-D) and petalorhynchid (E-F) petalodonts in lingual view. (A) Strigilodus tollesonae, this report. (B) Janassa linguaeformis, redrawn and modified from Hancock and Atthey (1869). (C) Janassa bituminosa, redrawn and modified from Hancock and Howse (1870). (D) Cypripediodens cristatus (Duffin and Ward 2017). (E) Petalorhynchus beargulchensis, redrawn and modified from Lund et al. (2014). (F) 'Janassa' ('Ctenoptychius') korni, redrawn and modified from Brandt (1996). Dentitions not drawn to scale. |
John-Paul M. Hodnett, Rickard Toomey, Rickard Olson, Justin S. Tweet and Vincent L. Santucci. 2023. Janassid petalodonts (Chondrichthyes, Petalodontiformes, Janassidae) from the middle Mississippian (Viséan) Ste. Genevieve Formation, Mammoth Cave National Park, Kentucky, USA. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2023.2231955
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