The dentition of the enigmatic pycnodont fish,Athrodon wittei(Fricke, 1876) (Neopterygii, Pycnodontiformes; Late Jurassic; NW Germany)

Abstract

Most pycnodontiform fishes are represented by their distinctive dentition alone, whereas articulated skeletons are very rare and the systematic position of most taxa based upon isolated teeth and the association of upper and lower dentitions to a specific taxon is still somewhat ambiguous in most cases. The vomerine dentition of the Late Jurassic pycnodontiform Athrodon wittei (Fricke, 1876), which is described here for the first time, is characterised by a high number of lateral tooth rows and the distinct morphology of the teeth. The dentition of Athrodon differs from most other pycnodont dentitions in the peculiar arrangement of the teeth into irregular rows and not well‐differentiated principal row. The absence of regular tooth rows is not considered plesiomorphic here but most probably was achieved independently in different pycnodont lineages. The high number of lateral tooth rows (> four) is considered to be autapomorphic for Athrodon. The pycnodont fish Nonaphalagodus from the Albian of Texas, which also is known by isolated dentitions only, resembles Athrodon in the high number of vomerine tooth rows but differs in that this taxon displays the more derived feature of the teeth being arranged more regularly and individualized rows. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Reassessment of Cosmodus Sauvage, 1879, a poorly known genus of large pycnodont fish (Actinopterygii, Pycnodontiformes) from the Cenomanian (Upper Cretaceous) of Western Europe

“…Our results confirm the important contribution of diagnostic isolated dentitions to our knowledge of the palaeodiversity, palaeobiogeography and palaeoecology of pycnodontiform fishes (e.g., Kriwet and Schmitz, 2005;Kriwet, 2008;Szabó et al, 2016;Stumpf et al, 2017). (Coquand, 1859) in the type area (Charentes region, northern Aquitaine Basin).…”

Early Jurassic diversification of pycnodontiform fishes (Actinopterygii, Neopterygii) after the end-Triassic extinction event: evidence from a new genus and species,Grimmenodon aureum

“…Pycnodontiform remains of Callovian age have been rarely reported in the literature. For instance, Kriwet ( 2008 ) figured an isolated left prearticular of an indeterminate species of Athrodon Sauvage, 1880b , recovered from the Callovian of Falaises des Vaches Noires near Dives-sur-Mer, Calvados, France. Unlike in Grimmenodon , gen. et sp.…”

“…(e.g., Agassiz, 1844 ; Bassani, 1885 ; Sauvage, 1867 , 1880a , 1880b ; Woodward, 1890 , 1892 , 1895 ; Kriwet et al, 1997 ); and Callovian: Mesturus leedsi , Gyrodus sp., and Athrodon sp. (Woodward, 1895 , 1896 ; Galton et al, 1980 ; Rioult and Mourdon, 1982 ; Kriwet, 2008 ). Cavin et al ( 2009 ) described a single right prearticular from the Middle–Late Jurassic of Mab Ching in the Khlong Min Formation, Thailand, which these authors tentatively referred to Gyrodus sp.…”

“…The validity of many taxa consequently remains ambiguous. Nevertheless, Longbottom ( 1984 ), Kriwet ( 1999 , 2005 , 2008 ), Poyato-Ariza and Bermúdez-Rochas ( 2009 ), and Shimada et al ( 2010 ), among others, demonstrated that the morphology and arrangement of teeth on the vomer and prearticulars in pycnodontiform fishes provide unique combinations of characters and even allow identifying autapomorphic traits for taxon assignment and establishing reliable diagnoses. The importance of recognized autapomorphic characters in phylogenetic analyses, however, needs to be tested.…”

New pycnodontiform fishes (Actinopterygii, Neopterygii) from the Early Cretaceous of the Argentinian Patagonia

“…Pycnodontiforms inhabited mostly coastal and also pelagic marine waters as well as brackish, freshwater-influenced and freshwater environments (Nursall, 1996a; Poyato-Ariza et al, 1998; Poyato-Ariza, 2005; Martín-Abad and Poyato-Ariza, 2013). Although most taxa only are known by their isolated dentitions or even teeth (e.g., Poyato-Ariza and Wenz, 2002; Kriwet, 2008; Stumpf et al, 2017), complete and well-preserved specimens occur in Mesozoic and Early Cenozoic Konservat-Lager-stätten deposits of the Tethys area (Lambers, 1991; Forey et al, 2003; Kriwet, 2005; Kriwet and Schmitz, 2005; Poyato-Ariza and Wenz, 2005; Ebert, 2013, 2018; Vullo et al, 2017). Moreover, some taxa previously assumed to be invalid such as the large pycnodontiform Cosmodus , which is based on isolated dentitions recently was redescribed and recognized as a valid distinct genus (Vullo et al, 2018).…”