Updated February 11, 2021
with new data some taxa are reordered.
Every day there are changes
in the ray-fin fish subset of the large reptile tree (LRT, 1796+ taxa). This constant involvement, day-after-day has been as rewarding as frustrating. Earlier we looked at some of the more interesting and unexpected pairings. Here (Fig. 1) is the latest iteration:
This, then, is a step back to look at the clade in toto,
to see if any taxa or clades don’t belong together. I don’t profess that this cladogram is finished or perfect. Rather, it is presented to expose its frailties in order to repair them.
Some takeaways (at present):
- Basalmost taxa are derived from Gregorius and the moray eel clade
- Basalmost taxa retain teeth on the maxilla and the parietals are not separated medially
- Basalmost taxa are related to spiny sharks on the other bony fish clade, the one that leads to placoderms, catfish, lobefins and tetrapods
- Basalmost taxa skew toward a deep sea niche today, perhaps not in the past
- Basalmost taxa radiated in the Late Silurian to Early Devonian
- Xiphactinus represents the largest size attained by tested clade members
- Sea horses, like Hippocampus, are among the smallest and least similar to ancestral taxa
- The loosening of the maxilla occurred by convergence several times
- The appearance of the palatine as a cheek bone occurred several times
- Basalmost taxa are generally small and slow. Transitional taxa are speedy, open-sea predators. Derived taxa return to bottom-dwelling sit-and-wait predation
- Some basal taxa (e.g. Amia) can breathe air. Lepidogalaxias estivates.
- Only the mudskipper, Periophthlamus (Fig. 2), crawls out above the surface, keeping its gills bathed with cheekfulls of water. No other ray-fin taxa develop anything like a crawling, lobe-like fin.