New carcharhiniform sharks (Chondrichthyes, Elasmobranchii) from the early to middle Eocene of Seymour Island, Antarctic Peninsula

Abstract

Seymour Island, Antarctic Peninsula, is known for its wealth of fossil remains. This island provides one of the richest fossiliferous Paleogene sequences in the world. Chondrichthyans seemingly dominate this Eocene marine fauna and offer a rare insight into high-latitude faunas during the Palaeogene. So far, only a few isolated teeth of carcharhinid sharks have been reported from Seymour Island. Bulk sampling in the well-exposed La Meseta and Submeseta formations yielded new and abundant chondrichthyan material, including numerous teeth of carcharhinid and triakid sharks. Here, we present a reevaluation of the previously described carcharhinid remains and a description of new taxa: Meridiogaleus cristatus, gen. et sp. nov., Kallodentis rythistemma, gen. et sp. nov., Abdounia richteri, sp. nov., and Abdounia mesetae, sp. nov. The carcharhiniforms Mustelus sp. and Galeorhinus sp. are reported based on rare material, whereas teeth previously assigned to Scoliodon represent a nomen dubium.

First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia

“…1c,d), and informally referred to as the 'Natica horizon' 8,13 . It has produced shark, ray and skate teeth, remains of marine bony fishes, as well as teeth of terrestrial mammals, worm (clitellate) cocoons, and seeds of water lilies 8,[12][13][14][15][16][17][18][19][20][21][22] . Based on dinocyst occurrences, the age of this deposit is considered to be about 40 Ma (Bartonian, Eocene) 23,24 .…”

Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota

“…The UCMP and PRI specimens were collected during Seymour Island Antarctic expeditions in 1986–1987 and 1989 sponsored by the National Science Foundation. Anterior tooth crown measurements for † S. macrota were supplemented by additional teeth from the Paleozoological Collections at the Swedish Museum of Natural History (NRM; Stockholm, Sweden), which are partially described in Kriwet et al (2016), Engelbrecht et al (2017a, 2017b, 2017c, 2017d, 2019), and Marramá et al (2018). NRM specimens were collected by an Argentinian‐Swedish field party as a joint project of the Instituto Antártico Argentino (DNA‐IAA) and the Swedish Polar Research Secretary (SPFS) during the summer campaigns from 2011–2013 on Seymour Island.…”

“…Paleoecological insight to sand tiger sharks from the La Meseta Fm. compliment and expand on the extensive systematic work to date on chondrichthyan fossils (i.e., Engelbrecht et al, 2017aEngelbrecht et al, , 2017bEngelbrecht et al, , 2017cEngelbrecht et al, , 2017dEngelbrecht et al, , 2019Kriwet, 2005;Kriwet et al, 2016;Long, 1992;Long & Stilwell, 2000) and geochemical analyses elucidate paleoceanographic conditions.…”

“…In addition, the La Meseta Fm. includes a fossil record rich with shark teeth; to date, there are 35 species from 22 families of Chondrichthyes, the class including chimeroids, batoids, skates, rays, and sharks identified and described from studies over the past 40 years (see, e.g., Engelbrecht et al, 2017aEngelbrecht et al, , 2017bEngelbrecht et al, , 2017cEngelbrecht et al, , 2017dEngelbrecht et al, , 2019Grande & Eastman, 1991;Kriwet, 2005;Kriwet et al, 2016;Long, 1992;Long & Stilwell, 2000;Marramá et al, 2018;Welton & Zinsmeister, 1980). Here, we delve into the paleoecology of the ancient sand tiger shark, †Striatolamia macrota (Agassiz), an extinct (denoted with †), cosmopolitan species found in Eocene nearshore deposits that span from the Arctic (Padilla et al, 2014) to Antarctica (Welton & Zinsmeister, 1980), including midlatitude sites in both hemispheres (Cappetta, 2012).…”

A new genus and species of extinct ground shark, †Diprosopovenator hilperti, gen. et sp. nov. (Carcharhiniformes, †Pseudoscyliorhinidae, fam. nov.), from the Upper Cretaceous of Germany

“…The oldest known fossil occurrences attributable to Carcharhiniformes date back to the Middle Jurassic (Underwood and Ward, 2004;Cappetta, 2012), and these sharks seemingly became more abundant and diverse during the Cretaceous (e.g., Ward, 2008a, 2008b;Guinot et al, 2013Guinot et al, , 2014 onward to the Cenozoic, when most of the more modern forms had their first appearances (see Cappetta, 2012, andMaisey, 2012, for summaries). The fossil record of carcharhiniforms (and elasmobranchs in general) is greatly dominated by isolated teeth, which occur frequently in a wide range of marine depositional settings, providing discrete taxonomic features (e.g., Ward, 2004, 2008a;Adnet, 2006;Underwood et al, 2011;Guinot et al, 2013Guinot et al, , 2014Carrillo-Briceño et al, 2016;Engelbrecht et al, 2017;Fuchs et al, 2018). Conversely, carcharhiniform skeletal material remains extremely scarce in the fossil record, particularly because their poorly mineralized cartilaginous endoskeletons are subject to specific taphonomic constraints and are, therefore, restricted to a few localities only (e.g., von der Marck, 1863; Cappetta, 1980;Klug, 2004, 2015;Marramà et al, 2018).…”