Celebrating 300 Taxa in the Large Reptile Tree

Science is all about constants.  
The evolution of reptiles has been set in stone (literally). What we’re looking for now is a constant model that reconstructs that family tree with clues provided by the fossils we know …and how well we know them. We want to remove all the former mystery from this pursuit. After all, it is 2012. Everything else has been figured out by now…why not the reptile?

So when the taxon list in the large reptile tree rises to 300, as it just did, its worth a look to see what changes have occurred. (It’s a milestone, after all).

First of all, nothing earth-shattering.
In fact, none of the new taxa have changed the tree topology (= original order (going back several tree generations)). This tree continues to grow in good health, becoming fuller as more leaves and nodes are added. All sisters continue to look alike, which is the key after all. That’s how evolution works. Descendants look like ancestors. Sisters look like sisters. In the large reptile tree former enigmas have been nested. Mistaken nestings created by smaller earlier and concurrent studies have been rectified. Additional taxa have been added without changing the tree topology. No other study on reptile relations can claim the same certainty and consistency.

I believe we have a very good tree here.
And I’m looking forward to the next milestones at 350 and 400 taxa (so far not counting the pterosaurs nor the therapsids). The present tree provides several tests of relationships, of bone identities and of sutures vs. cracks. Errors have been acknowledged and repaired. Oversights have been reexamined. Hopefully we all will never rest on our laurels, traditions or paradigms. I look forward to making changes, but only if it gets us closer to modeling more accurately the actual reptile family tree.

Keep those discoveries coming! 
And as I mentioned earlier, if ANYONE finds two taxa in the large reptile tree that should not be sisters, please bring these to my attention. So far no one has despite some earlier comments. If there are any mismatches, please let me know.

We’ll talk about it.

3 thoughts on “Celebrating 300 Taxa in the Large Reptile Tree

  1. Haha. Just among the dinosaurs- Scelidosaurus should move up to be sister to Scutellosaurus, Daemonosaurus should be a saurischian, Saturnalia should be basal to Thecodontosaurus+Massospondylus, Sauropodomorpha should be sister to Theropoda, poposaurs including Lotosaurus should be pseudosuchians, silesaurids should be outside Dinosauria, Pisanosaurus should be an ornithischian, Panphagia and Pampadromaeus should be sauropodomorphs, Marasuchus should be outside Dinosauria+Silesauridae, Trialestes should be a pseudosuchian…

    But no, I’m sure absolutely no one has ever brought any of these to your attention….

  2. Once again, where is your competing tree? Where are the bad characters? Which are the new generic sister taxa for those taxa you listed? Please be specific. As you know, it’s very bad practice to use suprageneric taxa in phylogenetic analysis, especially if they prove to be invalid (para/diphyletic). Thanks for stopping by.

  3. Competing trees- Butler et al. 92007) and derivitives for Ornithischia, Nesbitt (2011) for archosaurs, Nesbitt et al. (2009) and derivitives for Dinosauromorpha, etc., you know them all. For bad characters, I don’t have your reptile dataset. Do I have permission to post characters and critiques from your 2006 pterosaur analysis? For new sister taxa, sometimes suprageneric taxa are the sister taxon of a genus, which can be due to incomplete knowledge, but could be real too (e.g. a barrier forms, causing speciation of the separated populations, but one dies out before diversifying into what we would subjectively call more than one genus, while the other keeps speciating and turns out to be the basal population of some new large and diverse clade). You know all of the consensus ideas there too- Scutellosaurus is sister to Emausaurus+Scelidosaurus+Eurypoda, or to just Scelidosaurus in your tree; Daemonosaurus MAY be sister to Tawa+Aveopoda, but since good trees differ in basal saurischian relationships, I wouldn’t commit to any particular arrangement yet, etc..

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