The moray eel: close to the origin of all bony fish

Updated April 23, 2020
by adding taxa. This moved the moray eel, Gymnothorax (Fig. 2, 3), to nest with tiny Gregorius (Fig. 1), the outgroup taxon to all other bony fish.

Figure 1. Tiny Gregorius rexi nests basal to moray and gulper eels and also basal to all bony fish in the LRT.

Figure 1. Tiny Gregorius rexi nests basal to moray and gulper eels and also basal to all bony fish in the LRT.

Here
you can see the origin of the long straight tail of the moral eel evolving from the straight/diphycercal tail of Gregorius. The lateral fins are missing in the moray eel. Gregorius is a suitable predecessor despite its late appearance in the Early Carboniferous after a likely Late Silurian radiation.

Figure 1. Moray eel skeleton. Note the two gray dots represent absent fins.

Figure 2. Moray eel skeleton. Note the two gray dots represent absent fins. The apparent second set of jaws are gill bars able to jump forward to grab bitten prey and pull it back to the esophagus.

Many hundreds of millions of years have passed since the Devonian.
In the meantime one branch of lobefins gave rise to dinosaurs, bats, and blog readers. Another branch gave rise to most ray-fin fish. A third branch, a basal branch, gave rise to Gymnothorax, a newly recovered basalmost bony fish that lost several facial bones and four fins since the Devonian. What remains is a scale-less eel with a bad reputation.

Figure 2. The skull of the moray eel, Gymnothorax, in 3 views. Colors added as homologs to tetrapod skull bones. The nares exit is above the eyes.

Figure 3. The skull of the moray eel, Gymnothorax, in 3 views. Colors added as homologs to tetrapod skull bones. The nares exit is above the eyes.

Compare the snake-like skull of Gymnothorax
(Fig. 3) to Boa (Fig. 4). The convergence is remarkable.

Figure 6. Boa constrictor skull from 4 angles. Note the similarities, by convergence, to the Gymnothorax skull in figure 2.

Figure 4. Boa constrictor skull from 4 angles. Note the similarities, by convergence, to the Gymnothorax skull in figure 2.

Figure x. Subset of the LRT focusing on basal vertebrates. This represents the latest hypothesis of interrelationships and includes several changes from prior versions of this section.

Figure x. Subset of the LRT focusing on basal vertebrates. This represents the latest hypothesis of interrelationships and includes several changes from prior versions of this section.

Gymnothorax afer (Bloch 1795, type genus) Gymnothorax funebris (Ranzani 1839) is the extant green moray eel, which has no limbs or fins and traditionally nests within the Teleostei. Here this 2m eel nests with Gregorius, a much more primitive node than basal Teleostei. Several cheek bones are also reduced or missing. Note the elongate torso (Fig. 1), prior to the anterior chevrons. That is a primitive trait in vertebrates.

Figure 7. GIF animation showing the dual bite of the dual jaws in moray eels. Both are derived from gill bars.

Figure 6. GIF animation showing the dual bite of the dual jaws in moray eels. Both are derived from gill bars. Note: this makes Gymnothorax one of the few fish with a neck, prior to what would have been the pectoral girdle. Seahorses are another. The external naris exit is that little pipe above the orbit. This skull is an inaccurate cartoon. The naris does not perforate the skull at midline  nor is the skull split at midpoint in reality. Compare to figure 2.


References
Bloch ME 1795. Naturgeschichte der ausländischen Fische. Berlin. v. 9. i-ii + 1-192, Pls. 397-429.

wiki/moray eel

2 thoughts on “The moray eel: close to the origin of all bony fish

  1. Is it possible for you to make your supermatrix public? I’m interested in your methods. Perhaps a link to a google drive or dropbox file easily accessible from your sites?

    • Jake, a supermatrix is a collecion of previously published (and typically uncorrected) matrices. The LRT is just a big matrix. It has been updated daily lately. My methods are posted daily at the blogsite; tracing photos, making reconstructions, scoring traits. ReptileEvolution.com is the collection of taxa in phylogenetic order, now almost 8 years old. The .nex file is available by request here: http://www.reptileevolution.com/reptile-tree.htm top right hand corner. I didn’t see a request in the comment. Let me know through the above url and you’ll get a .nex file via email. Dave

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