Enigmatic Niobrara tuna-mimic, Pentanogmius, enters the LRT with extant Amia, the bowfin

Another enigma taxon resolved by the LRT!
Pentanogmius evolutus (originally Bananogmius evolutus Cope 1877; Taverne 2004; Late Cretaceous; 1.7m long; DMNS 57159) is a tuna-mimic with a high dorsal fin traditionally considered a member of the Tselfatiiformes. Paleo fish workers are not still sure where Tselfatiiformes nest within the Actionopterygii (bony fish). This one lived in the Western Interior Sea over what is now the plains of Kansas, home of giant pterosaurs, elasmosaurs and mosasaurs.

Figure 1. Pentanogmius in situ and reconstructed by Traverne 2004. Note the long dorsal fin, pelvic fins close to the anal fin and the 31+ precaudal vertebrate, as in Amia. The tail is evolved to the diphycercal shape.

in the large reptile tree (LRT, 1977+ taxa), Pentanogmius nests readily with Amia, the extant bowfin (Fig. 3). Amia is traditionally considered a member of the invalid clade, Holostei, so it was not considered a possible sister candidate in prior studies.

Figure 2. Skull of Pentanogmius traced and reconstructed using DGS.

Compared to Amia
(Fig. 3), Pentanogmius is taller and narrower overall with a longer premaxilla and smaller teeth. This genus represents yet another case of a convergent diphycercal tail shape.

Figure 2. Skeleton of the extant bowfin (Amia).
Figure 3. Skeleton of the extant bowfin (Amia).

According to Wikipedia,
“The tselfatiiforms could not initially be assigned to a larger kinship group within the Teleostei.” Taverne and Gayet 2005 considered clade members to be clade members of the Clupeocephala (= piranha, salmon, herring, and others). Amia was not considered. In the LRT these taxa are also descendants of Amia, the bowfin.

This appears to be a novel hypothesis of interrelationships.
If not, please provide a prior citation and I will promote it here. For all such enigma taxa, add taxa to find out where they nest. I have not seen the fossil firsthand. I simply let the software do the work on a larger list of taxa, as the LRT did earlier with pterosaurs, turtles, whales, snakes, dinosaurs, reptiles, etc. etc. over the last twenty years.

Cope ED 1877. On some new or little known reptiles and fishes of the Cretaceous of Kansas. Proceedings of the American Philosophical Society 17: 176-181.
Taverne L 2001. Révision du genre Bananogmius (Teleostei, Tselfatiiformes), poisson marin du Crétecé supérior d’Amérique du Nord et d’Europe. Geodiversitas 23(1):17-40. (Revision of the genus Bananogmius (Teleostei, Tselfatiiformes), marine fish from the Upper Cretaceous of North America and Europe).
Taverne L 2004. Ostéologie de Pentanogmius evolutus (Cope, 1877) n. comb. (Teleostei, Tselfatiiformes) du Crétacé supérieur marin des États-Unis. Remarques sur la systématique du genre Pentanogmius Taverne, 2000.
Taverne L and Gayet M 2005. Phylogenetical relationships and palaeozoogeography of the marine Cretaceous Tselfatiiformes (Teleostei, Clupeocephala). Cybium 2005, 29 (1)

wiki/Pentanogmius – not yet listed


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.