Revisting Protosphyraena (Late Cretaceous)

Revised May 16, 2020
with the addition of Early Jurassic Ohmdenia, a new taxon that attracts enigmatic Protosphyraena to the osteoglossiformes. They all share a spine-like pectoral fin along with matching dorsal and anal fins.

New data on the Late Cretaceous ‘swordfish with teeth’
Protosphyraena nitida (Leidy 1857; Late Cretaceous; 3m; Figs. 1) brings it up for review and reconsideration. It was originally considered a basal baraccuda and traditionally is now considered a member of the Pachycormiformes, but here nests nearby as a sister to coeval Niobrara Ohmdenia, related to the extant arowana, Osteoglossum.

Distinct from Ohmdenia
Protosphyraena had a swordfish-like body, head and tail (Fig. 1).

Figure 1. Skull of Protosphyraena. Colors added to march tetrapod homologies and updated here from previous guesstimates. Comapare to figures 3 and 4.

Figure 1. Skull of Protosphyraena. Colors added to march tetrapod homologies and updated here from previous guesstimates. Comapare to figures 3 and 4.

Like Hybodus,
and most bony fish, the lacrimal + premaxilla + maxilla are essentially fused to the cranium. That added to the confusion.

Figure x. Newly revised fish subset of the LRT

Figure x. Newly revised fish subset of the LRT

The new nesting of Protosphyraena
as a highly derived taxon makes sense. This is a unique taxon leaving no descendants.


References
Leidy J 1857. Remarks on Saurocephalus and its allies. Transactions of the American Philosophical Society. 11: 91–95.

http://reptileevolution.com/polyodon.htm

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