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.