Adding basal snake taxa unites snakes in one clade

Earlier, with fewer taxa in the large reptile tree, small blind burrowing snakes, like Uropeltis,  nested with Heloderma and Lanthanotus, while more more terrestrial sighted snakes nested with gecko sisters, including Eichstaettisaurus, Adriosaurus and Dolichosaurus.

Figure 1. A subset of the large reptile tree focusing on squamates. Note snake ancestors are still sisters to basal geckos.

Figure 1. A subset of the large reptile tree focusing on squamates. Note snake ancestors are still sisters to basal geckos.

With the addition of several basal snakes (Fig. 1), like Xenopeltis and Loxocemus (which are found both above and below ground), the burrowing snakes join the terrestrial snakes in a single clade, still derived from gekko sisters like Tchingisaurus.

I’m glad to see this happen. I’m always happy to make repairs when needed whether to my own work or elsewhere. Making repairs is always a good thing in Science. Adding taxa, which is what I continue to do with the large reptile tree (now 498 taxa), is often the key to understanding reptile relationships.

I would have liked to have done this much sooner, but no one suggested adding more basal snake taxa to make this correction. There’s no time limit here, so corrections will be made as they arise.

If you take all the burrowing snakes that used to nest with Lanthanotus and Heloderma, and force them back onto that node, the most parsimonious tree adds just 13 steps. The typical jump in steps between most adjoining  sister taxa is 3 to 8. So 13 for an entire clade bump is not a big number. Convergence is rampant within the Reptilia, and quite rampant within the Squamata, a notoriously difficult clade to work with, as many have experienced, as shown here with several competing tree topologies by professional paleontologists over the past few decades. Figure 1 is the latest such entry, prone to modify as new data comes in.

 

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