Oldest lepidosaur? Part 2
Yesterday we looked at
Middle Triassic Agriodontosaurus (Figs 1, 2, Marke et al 2025), mistakenly promoted as the oldest lepidosaur.
Older lepidosaurs are known from the Permian. Those were listed yesterday
and were either overlooked or omitted or misunderstood in the taxon list of Marke et al 2025. That means their study suffered from the most common problem in paleontology: taxon exclusion. That is minimized as a problem in the LRT by size alone.
Figure 1. Agriodontosaurus compared to Gephyrosaurus. You’ll note Marke et al employed the original reconstruction of Gephyrosaurus in their reconstruction of Agriodontosaurus.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg?w=584″ class=”size-full wp-image-94449″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg” alt=”Figure 1. Agriodontosaurus compared to Gephyrosaurus. You’ll note Marke et al employed the original reconstruction of Gephyrosaurus in their reconstruction of Agriodontosaurus.” width=”584″ height=”358″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg?w=584&h=358 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg?w=150&h=92 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg?w=300&h=184 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus-graphic588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. Agriodontosaurus compared to Gephyrosaurus. You’ll note Marke et al employed the original reconstruction of Gephyrosaurus (Evans 1981) in their reconstruction of Agriodontosaurus.
Today, after phylogenetic analysis
in the large reptile tree (LRT, 2337 taxa) Middle Triassic Agriodontosaurus nests with Early Jurassic Gephyrosaurus (Figs 1, 2, Evans 1980, 1981) close to the base of the Rhynchocephalia – DESPITE those fewer and much larger teeth in Agriodontosaurus, which are unlike those of any related lepidosaurs.
This nesting in the LRT confirms the nesting published by Marke et al 2025. Both hypotheses of interrelationships point to a much older last common ancestor for the clade that eventually produced these two similar, but different taxa (Fig 2).
Figure 2. Agriodontosaurus µCT scans and diagrams from Marke et al 2025 here compared to Gephyrosaurus. DGS colors added or modified here.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg?w=584″ class=”size-full wp-image-94451″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg” alt=”Figure 2. Agriodontosaurus µCT scans and diagrams from Marke et al 2025 here compared to Gephyrosaurus. DGS colors added or modified here. ” width=”584″ height=”481″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg?w=584&h=481 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg?w=150&h=123 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg?w=300&h=247 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/09/agriodontosaurus.skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 2. Agriodontosaurus µCT scans and diagrams from Marke et al 2025 here compared to Gephyrosaurus. DGS colors added or modified here. In the Agriodontosaurus diagram the mandible does not contact the quadrate when the jaws are closed and the teeth overlap. Arrows indicate shifting of the elements between the three views. Don’t let this happen to your reconstruction. Put the elements together to check for fit.
When authors start to standardize DGS colors
then comparisons will be more readily made between taxa, between publications. Arrows on the Marke et al diagram of the skull of Agriodontosaurus indicate several shifts of points in their freehand graphic. Ideally all lines should be parallel, not diverging and converging.
Marke et al attempted to create standard and strict dorsal, lateral and palatal views from scans that were not strictly dorsal, lateral and palatal views, but angled off to the side somewhat in each case.
References
Evans SE 1980. The skull of a new eosuchian reptile from the Lower Jurassic of South Wales. Zoological Journal of the Linnean Society 70: 203–264.
Evans SE 1981. The postcranial skeleton of the Lower Jurassic eosuchian Gephyrosaurus bridensis. Zoological Journal of the Linnean Society 73:81–116.
Marke D et al (7 co-authors including MJ Benton) 2025. The oldest known lepidosaur and origins of lepidosaur feeding adaptations. Nature. https://doi.org/10.1038/s41586-025-09496-9
wiki/Gephyrosaurus
wiki/Lepidosauria
Publicity
science.org/content/article/incredible-fossil-reveals-earliest-relative-lizards-and-their-kin
phys.org/news/2025-09-lizards-ancient-fossil-ancestral-traits.html
bristol.ac.uk/news/2025/september/lizards.htm
Source: https://pterosaurheresies.wordpress.com/2025/09/11/oldest-lepidosaur-part-2/
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