Taxonomic problems? Go back to the holotype.

Sometimes taxa are mislabeled.
Such is the case with Pholidophorus? radians (Figs. 1–3), a ‘herring-like’ Jurassic (Solnhofen Fm.) fish with ganoid scales, tiny fins and a large forked tail. This specimen (Fig. 1) was identified as Pholidophorus in The Rise of Fishes (Long 1995) and at the Wikipedia entry for Pholidophorus.

Figure 3. Pholidophorus in situ and two skulls attributed to this genus. Compare the one on the left to figure 2. No tested fish in the LRT is closer to Robustichthys than Pholidophorus.

Figure 1. Pholidophorus in situ and two skulls attributed to this genus from Long 1995. Neither diagram matches this specimen, despite overall similarities.

The images in the diagrams above
(Fig. 1) are indeed variations on Pholidophorus (Fig. 4). However, the specimens in the photographs (Figs. 1–3) nest with Elops, the ladyfish (or tenpounder) in the large reptile tree (LRT, 1668+ taxa) on the other branch of bony fish.

Figure 2. Another specimen of Pholidophorus? radians

Figure 2. Another specimen attributed to Pholidophorus? radians

Figure 3. DGS tracing of Pholidophorus? radians along with a reconstruction moving the crushed bones to their invivo positions.

Figure 3. DGS tracing of Pholidophorus? radians along with a reconstruction moving the crushed bones to their invivo positions.

Yesterday
I found the Pholidophorus latiusculus holotype in the literature (Arratia 2013; Late Triassic; Fig. 4). The LRT recovered it apart from the Solnhofen (Late Jurassic) specimen identified as Pholidophorus in Long 1995 and Wikipedia.

The Late Triassic holotype of Pholidophorus
nests with Osteoglossum, the extant arrowana of South America and spiny-finned Bonnerichthys, from the Niobrara Sea of the Cretaceous. All likely had their genesis in the Late Silurian based on their close-to-the-base phylogenetic node.

Figure 4. Pholidophorus holotype from Arratia 2013, overlay drawing from Agassiz 1845.

Figure 4. Pholidophorus holotype from Arratia 2013, overlay drawing from Agassiz 1832.

It is easy to see how later specimens
were allied with the holotype, but this turns out to be yet another case of convergence. A wide gamut phylogenetic analysis that minimizes taxon exclusion minimizes phylogenetic errors like this one. Earlier I made the mistake of combining the data from the diagram (Fig. 1) and the photo (Fig. 2) creating a chimaera. Best to just find the holotype and work from that.


References
Agassiz L 1832. Untersuchungen über die fossilen Fische der Lias-Formation. Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde, 3, 139–149.
Arratia G 2013. Morphology, taxonomy, and phylogeny of Triassic pholidophorid fishes (Acinopterygii, Teleostei). Journal of Vertebrate Paleontology 33:sup1:1–138.
Sallan LC 2012. Tetrapod-like axial regionalization in an early ray-finned fish. Proceedings of the Royal Society B 279:3264–3271.

wiki/Pholidophorus

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