The mammal subset of the LRT is at a stopping point

The synapsid/mammal subset
of the large reptile tree (LRT, 2340 taxa) has arrived at a stopping point = it’s done. At least, for now, it’s as finished as it can be.

That means the interrelationships recovered by the LRT seem to make sense.

That means sister taxa throughout appear to be the result of microevolution.

That means they look like each other, and look like they could have evolved one from another, without any odd disjointed pairings.

Unfortunately,
this subset of the LRT is also more fragile than any other similar subset of the LRT with 600+ taxa. Practically that means deletion of one mammal taxon can add many instances of ‘loss of resolution’ at several nodes in a wide spectrum up and down the taxon list while ironically reducing the number of MPTs overall. That is disheartening.

(Don’t ask me how or why that happens. It’s a puzzlement.)

So, that’s what we’re dealing with: a fragile conclusion.
Mammals are different than other chordate subsets. Mammals converge here and there. Some substitute a first premolar for a reduced and lost canine. Males differ from females. Juveniles have fewer teeth than adults. Placental reproduction appeared by convergence 5x at present.

It took 600+ 12-hour days of housekeeping
to fine tune 600+ mammals to the present fragile state of interrelationships. Every day I learned something new. Mistakes were made along the way, as the number of corrections rose to six then seven figures employing data that ranged from µCT scans in several views to century-old engravings without a dorsal or palatal view.

Thank you for your patience as I slogged through this quagmire.

So, it’s been a journey of frustration and elation
= discovery in a stepwise fashion. The LRT started in late 2010, so here at the start of 2026 the LRT has been a 16-year-long thesis project without an advisor and without hope or goal of achieving a degree. No $$. No fame. Just an interest in finding out.

This journey was made possible
by a quick access digital library of color-coded skulls and skeletons. The work could not have been started or finished without the many workers who posted data in library journals and on the web over the decades.

I was driven by
a vacuum (or several vacuums) that needed to be filled in this topic. While others focused on finding taxa, digging out fossils and studying a few skeletons in their lifetime, it was my task to take 2500 skeletons and arrange them in order and in vivo poses. Several times I discovered interrelationships that others overlooked. It was my task to sweep up the litter after others had published on various taxa.

I discovered no new taxa. My job was to join them together.

Other workers must have also experienced similar frustrations.
Perhaps that’s why academic workers stopped testing traits and passed this task over to genomic testing.

Unfortunately too often genomics did not recover similar interrelationships.
(Again, it’s a puzzlement.)

Unfortunately genomic interrelationships became widely accepted despite the obvious dicontinuities and its avoidance of fossil taxa.

The interrelationships recovered by the LRT
represent a hypothesis = stab at understanding how extinct and extant taxa are interrelated. The first stab was by Linneaus. Others have followed. All hypotheses require others to confirm, refute or modify their findings. The LRT is a contribution. It can be ignored or it can serve as a guide, a list of taxa that probably should be tested in future, smaller, more focused studies. I can’t imagine anyone else spending 16 years trying to figure out if badgers are small bears or bears are large badgers, etc. etc. etc.

All data = matrices for the LRT
are available online at FigShare.com. Look for ‘The ReptileEvolution.com project” in your keyword search.

Web pages now need to be repaired and updated at ReptileEvolution.com.

Ed note: I see six comments in the queue now. I will get to them over the next few days. Thank you for your comments, your patience and your interest in paleontology and systematics.

Source: https://pterosaurheresies.wordpress.com/2026/01/06/the-mammal-subset-of-the-lrt-is-at-a-stopping-point/