Wednesday, February 7, 2024

[PaleoIchthyology • 2024] Troglocladodus trimblei & Glikmanius careforum • New ctenacanth Sharks (Chondrichthyes: Elasmobranchii: Ctenacanthiformes) from the Middle to Late Mississippian of Kentucky and Alabama, USA


  Troglocladodus trimblei 
 Glikmanius careforum 

Hodnett, Toomey, Egli, Ward, Wood, Olson, Tolleson, Tweet & Santucci, 2024
 Artwork by Benji Paynose.

Two new ctenacanthiform sharks representing two families, Ctenacanthidae and Heslerodidae, have been identified from the Middle to Late Mississippian marine sediments from Mammoth Cave National Park, Kentucky, and two Late Mississippian marine horizons in northern Alabama. The ctenacanthid, Troglocladodus trimblei, gen. et sp. nov., is known from isolated teeth from the Middle Mississippian St. Louis Formation and Ste. Genevieve Formation of Mammoth Cave and the Late Mississippian Bangor Limestone of northern Alabama. Troglocladodus gen. nov. is characterized by broad median cusps, pronounced longitudinal cristae, multiple intermediate cusps, and labiolingually shortened tooth bases. The heslerodid, Glikmanius careforum sp. nov., is known from isolated teeth and visceral arches from the Middle Mississippian St. Louis Formation and Ste. Genevieve Formation and the Late Mississippian Haney Formation, a Hartselle Sandstone-equivalent shale interval, and Bangor Limestone. Glikmanius careforum sp. nov. has proportionately distinct teeth among species of Glikmanius, with more robust and shorter cusps. The palatoquadrate of G. careforum has a short palatine ramus, otic process that is dorsoventrally deep and less expanded antero-posteriorly similar to Heslerodus and Dracopristis, and an elongated quadrate process like Heslerodus. The Meckel’s cartilage is less dorsoventrally deep than Dracopristis. These two new ctenacanth taxa add important information on the diversity of Ctenacanthiformes suggesting three major lineages within the order. Ctenacanths have a rich fossil history from the Late Devonian to the Middle Permian evolving a variety of tooth types and small to large body sizes.

Troglocladodus trimblei gen. et sp. nov.
Glikmanius careforum sp. nov.

An illustration of three large sharks swimming in blue waters above a coral reef. A reconstruction of the new Middle to Late Mississippian ctenacanth sharks from Mammoth Cave National Park and northern Alabama. Glikmanius careforum is seen swimming in the foreground with two Troglocladodus trimblei swimming above. Artwork by Benji Paynose.

John-Paul M. Hodnett, Rickard Toomey, H. Chase Egli, Gabe Ward, John R. Wood, Rickard Olson, Kelli Tolleson, Justin S. Tweet and Vincent L. Santucci. 2024. New ctenacanth Sharks (Chondrichthyes; Elasmobranchii; Ctenacanthiformes) from the Middle to Late Mississippian of Kentucky and Alabama. Journal of Vertebrate Paleontology.  e2292599 | DOI: 10.1080/02724634.2023.2292599  

Two new species of ancient sharks identified through research at Mammoth Cave National Park

Reconstruction of the shallow marine environment and its fauna of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky. 
Art by Julius Csotonyi.

A focused search for ancient Mississippian Subperiod marine vertebrates during a paleontological resource inventory of Mammoth Cave National Park, Kentucky, has yielded a wealth of new fossil data, previously unrecognized at this park. To date, we have identified marine vertebrate fossils from four primary horizons at the park, two of which are the first records of marine vertebrate fossils occurring in those horizons. Mammoth Cave sites have produced more than 70 species of ancient fish, about 90% representing cartilaginous fishes (sharks and kin), including several new species. The paleontological resource inventory of Mammoth Cave demonstrates that this park is an important resource for providing data on how fish assemblages changed during the formation of the super-continent Pangea. The inventory data also can help correct antiquated information on fossil sharks found in the region (in some cases not updated since their publication in the late 19th century).

Hodnett, John-Paul M.; Toomey, Rickard; Olson, Rickard; Tolleson, Kelli; Boldon, Richard; Wood, Jack; Tweet, Justin S. and Santucci, Vincent L. 2024. Sharks in the Dark: Paleontological resource inventory reveals multiple successive Mississippian Subperiod cartilaginous fish (Chondrichthyes) assemblages within Mammoth Cave National Park, Kentucky. Parks Stewardship Forum. 40(1). DOI: 10.5070/P540162921