2021 Paliguana paper suffers from taxon exclusion

Ford et al (4 co-authors) 2021
looked at the ‘enigmatic diapsid Paliguana whitei (Broom 1903, AM 3585, skull length 3cm, Fig 1) and the early history of Lepidosauromorpha.

Figure 1. Taxa at the base of the Lepidosauria include Paliguana, Tridentinosaurus, Lanthanolania, Lacertulus, Gephyrosaurus, Megachirella, Lacertulus and Palaegama. ” data-image-caption=”

Figure 1. Taxa at the base of the Lepidosauria include Paliguana, Tridentinosaurus, Lanthanolania, Lacertulus, Gephyrosaurus, Megachirella, Lacertulus and Palaegama.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=102″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=347″ class=”size-full wp-image-50425″ src=”https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=584&h=1721″ alt=”Figure 1. Taxa at the base of the Lepidosauria include Paliguana, Tridentinosaurus, Lanthanolania, Lacertulus, Gephyrosaurus, Megachirella, Lacertulus and Palaegama.” width=”584″ height=”1721″ srcset=”https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=584&h=1721 584w, https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=51&h=150 51w, https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg?w=102&h=300 102w, https://pterosaurheresies.files.wordpress.com/2020/10/basal_lepidosaurs588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. From 2020: Taxa at the base of the Lepidosauria include Paliguana, Tridentinosaurus, Lanthanolania, Lacertulus, Gephyrosaurus, Megachirella, Lacertulus and Palaegama.

Here
in the large reptile tree (LRT, 2314 taxa) Early Triassic Paliguana nests at the base of the Lepidosauriformes. The origin of the Lepidosauromorpha extends back to the Viséan (Early Carboniferous. Adding taxa recovered this hypothesis of interrelationships in 2011.

From the abstract
“Lepidosaurs include lizards, snakes, amphisbaenians and the tuatara, comprising a highly speciose evolutionary radiation with widely varying anatomical traits.”

In the LRT lepidosaurs also include Tridentinosaurus and the so-called ‘rib’ gliders, drepanosaurs, Huehuecuetzpalli, macrocnemids, tanystropheids and pterosaurs on one traditionally omitted lineage, trilophosaurs, azhendosaurs and rhynchosaurs on the other traditionally omitted lineage. It is unfortunate that universities continue to use out-dated textbooks that do not test these taxa, but continue to borrow cladograms from the past that cherry-picked their taxon lists to get academic approval = don’t rock the boat.

“Their stem-lineage originated by the late middle Permian 259 million years ago, but its early fossil record is poorly documented, obscuring the origins of key anatomical and functional traits of the group”

Since these authors were using cherry-picked cladograms that omitted taxa it is no wonder that they sincerely considered prior records as ‘poor’. But that’s what paleontologists often do to make their paper seem more important. That’s the game they have to play. According to the LRT the Ford et al taxon list is incomplete.

“Paliguana whitei, from the Early Triassic of South Africa, is an enigmatic fossil species with the potential to provide information on this.”

The skull of Paliguana (Figs 2,3) is actually well preserved and well documented. Sister taxa (Fig 1) provide post-cranial clues.

“However, its anatomy and phylogenetic affinities remain highly uncertain, and have been debated since its discovery more than 100 years ago.”

Figure 2. From Ford et al 2021, the skull of Paliguana in white light and after µCT scanning. ” data-image-caption=”

Figure 2. From Ford et al 2021, the skull of Paliguana in white light and after µCT scanning.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=584″ class=”size-full wp-image-84744″ src=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=584&h=404″ alt=”Figure 2. From Ford et al 2021, the skull of Paliguana in white light and after µCT scanning.” width=”584″ height=”404″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=584&h=404 584w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=150&h=104 150w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg?w=300&h=208 300w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana.skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 2. From Ford et al 2021, the skull of Paliguana in white light and after µCT scanning. Note how the ≤CT scan appears to be ‘over exposed’ omitting the rims of bones and teeth visible in white light.

Figure 3. Skull of Paliguana used to score it for the LRT in 2016. ” data-image-caption=”

Figure 3. Skull of Paliguana used to score it for the LRT in 2016.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=584″ class=”size-full wp-image-84745″ src=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=584&h=276″ alt=”Figure 3. Skull of Paliguana used to score it for the LRT in 2016.” width=”584″ height=”276″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=584&h=276 584w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=150&h=71 150w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg?w=300&h=142 300w, https://pterosaurheresies.files.wordpress.com/2024/03/paliguana588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 3. Skull of Paliguana used to score it for the LRT in 2016.

Ford et al set up a straw man argument,
“an intentionally misrepresented proposition that is set up because it is easier to defeat than an opponent’s real argument.” If this was not intentional, but accidental, Ford et al fare no better in a sin of omission rather than commission.

Adding taxa resolves this problem/oversight in the LRT.

“We present microtomographic three-dimensional imaging of the cranial anatomy of P. whitei that clarifies these uncertainties, providing strong evidence for lepidosauromorph affinities based on the structure of the temporal region and the implantation of marginal dentition.”

When Paliguana was entered into the LRT there was no need for µCT scans. The original studies were sufficient. 3D scans cannot solve taxon exclusion problems. Moreover, the presented µCT scans overexpose and thus omit several areas, edges and rims of teeth and bone that are visible in white light. That means some µCT scans introduce new problems as they resolve old ones.

Adding taxa resolves this problem/oversight in the LRT.

“Phylogenetic analysis including these new data recovers Paliguana as the earliest known stem-lepidosaur, within a long-lived group of early diverging lepidosauromorphs that persisted to at least the Middle Jurassic.”

Taxon exclusion (= cherry-picking taxa) hobbles this analysis.
Adding taxa resolves all phylogenetic problems.

“Our results provide insights into cranial evolution on the lepidosaur stem-lineage, confirming that characteristics of pleurodont dental implantation evolved early on the lepidosaur stem-lineage. By contrast, key functional traits related to hearing (quadrate conch) and feeding (streptostyly) evolved later in the lepidosaur crown-group.”

The Early Triassic of Paliguana is several tens of millions of years too late.
This clade had much earlier origins.

From ReptileEvolution.com/Paliguana.htm
from 2016, “Paliguana and Saurosternon nest at the base of the Lepidosauriformes, defined by Gauthier, deQuieroz and Estes (1988) as Sphenodon and squamates and all organisms sharing a more recent common ancestor than they do with younginiforms. They intended this to include Paliguana, Saurosternon, Kuehneosauridae, Rhynchocephalia and Squamates, but in the context of the present study their Lepidosauriformes would be redundant with the current Lepidosauromorpha. Redefined, the Lepidosauriformes now includes Paliguana, Sphenodon, their most recent common ancestor and all of its descendants. That now includes rhynchosaurs, trilophosaurs and pterosaurs which were formerly excluded. “

The Ford et al outgroups for Archosauromorpha + Lepidosauromorpha
include only Petrolacosaurus, Acerosodontosaurus (but which one?), Youngina (but which one) and Claudiosaurus. All of these are members of the Archosauromorpha not related to Paliguana and Lepidosauriformes. So what are they doing there? These are cherry-picked taxa and represent a misunderstanding of the actual phylogeny of reptiles. The LRT outgroup for Archosauromorpha + Lepidosauromorpha is Silvanerpeton from the Viséan (Early Carboniferous) recovered during the testing of 2315 taxa.

Cherry-picking taxa has been minimized in the LRT by sheer volume.

References
Broom R 1903. On the Skull of a True Lizard (Paliguana whitei) from the Triassic of South Africa. The Journal of Geology 11(5): 516-516.
Ford DP, Evans SE, Choiniere J, Fernandez V and Benson RBJ 2021. A reassessment of the enigmatic diapsid Paliguana whitei and the early history of Lepidosauromorpha. Proceedings of the Royal Society B 288(1957):20211084

wiki/Paliguana