Changes to the ray-fin clade of the LRT

A review of taxa, characters and scores
in this bedeviling corner of the large reptile tree (LRT, (1839+ taxa; subset Fig. 1) shifted several taxa to new nodes, resolving many phylogenetic problems and shedding new light on previous anatomical misinterpretations.

Figure 1. Subset of the LRT focusing on changes in the ray-fin subset.

Sauropsis longimanus
is a traditional pachycormiform, but here (Fig. 1) nests alongside Early Cretaceous Calamopleurus and the sea gurnard, Dactylopterus (Fig. 2).

Figure 2. Dactylopterus, the flying gurnard, looks like a sea robin (Prionotus) but nests with other bottom-dwelling, squarish cross-section basal ray fin fish in the LRT.

Dactylopterus volitans,
the flying gurnard (Fig. 2), is typically and traditionally allied with pipefish and seahorses. Earlier the LRT nested it with the similar sea robin, Prionotus, a scorpionfish. Now, after review, Dactylopterus nests with a more similar basal ray-fin fish from the Early Cretaceous, Calamoplerus, famous for its full arcade of long fangs. A peek inside the tail of Dactylopterus reveals a heterocercal tail, a primitive trait retained from shark ancestors.

Esox,
the freshwater muskellunge, now nests with a somewhat similar seawater predator, the needlefish, Tylosurus armed with a longer, tooth-filled rostrum. Transitional taxa remain unknown and untested at present. Traditionally Esox is the sole member of the clade Esociformes.

Satanichthys
was originally and traditionally considered the oldest characiform (= catfish, knifefish, carp). Earlier the LRT nested Santanichthys as a tiny hatchling of a much larger Santana Formation herring, Notelops. After review Satanichthys now nests as a tiny bonefish with the larger Albula and the deepsea barrel-eye, Opisthoproctus.

Figure 3. The threadfin, Polydactylus, also splits the pectoral fin to form threadlike feelers.
Figure 3. The threadfin, Polydactylus, splits the pectoral fin to form threadlike feelers, like unrelated flying gurnard (Fig. 2) and the sea robin.

Polydactylus,
the extant threadfin, has been a constant pain to understand given the present set of taxa. Until recently no others shared a shark-like nasal extending beyond the underslung jaws (Fig. 3). Threadfins are otherwise different from other taxa with pre-pectoral fin rays: sea robins and flying gurnards (Fig. 2). The recent addition of the extant deep sea rat tail (Coryphaenoides) solved that problem. Both are derived from Gadus, the cod. Traditionally threadfins are considered Perciformes (perch-like) fish.

Paleocene Massamorichthys
was originally nested close to similar tuna and mackerel relatives. After review it nests just one node down, basal to Danio, the tiny zebra fish, which is basal to sticklebacks, pipefish and sea horses in the LRT.

Apologies for the earlier mistakes.
I’m learning as I go, trying to be as transparent as possible while adding taxa one at a time in a haphazard (= random) fashion. Each new taxon sheds light on earlier interpretations. So these recent revisions represent progress, like chipping out a recognizable , complex and polished figure from a block of marble. There is no all-knowing paleo teacher to guide any of us. Rather traditional studies are shown to be riddled with errors after testing in the LRT, usually due to taxon exclusion. Research takes scientists into unexplored territories. There are few to no other people on this planet working on these problems in this fashion. Thank you for your readership and patience with the process and the struggle.

Never trust.
Always test.

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