Avicranium 2024: mistakes galore
Buffa et al 2024 hoped to convince readers
that their freehand drawings of the skull of Avicranium (Figs 1, 2) were superior data to the µCT scans of Pritchard and Nesbitt 2017. Buffa et al reported, “Contrary to previous interpretations, the entire rostrum and most of the palate are not preserved in this specimen.”
Freehand reconstructions are always biased due to artistic inaccuracy. Don’t freehand, if possible. Instead, borrow the scans from the earlier studies (Fig 2).
In 2018 Avicranium was reconstructed anew (Fig 2) with a premaxilla and maxilla based on the Bauplan of sister Vallesaurus. Buffa et al are mistaken in their assertion, identification and reconstruction of rostral elements.
To make matters worse
Buffa et al reported they reconstructed Avicranium based on the Bauplan of Megalancosaurus – even though they nested Avicranium with Vallesaurus, confirming the nesting in the LRT in 2018 (Fig 2).
Figure 1. The skull of Aviranium reconstructed by Buffa et al (left) and Pritchard and Nesbitt (right).
” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=296″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=584″ class=”size-full wp-image-85973″ src=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=584&h=592″ alt=”Figure 1. The skull of Aviranium reconstructed by Buffa et al (left) and Pritchard and Nesbitt (right). ” width=”584″ height=”592″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=584&h=592 584w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=148&h=150 148w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg?w=296&h=300 296w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. The freehand skull of Aviranium reconstructed by Buffa et al (left) and the µCT scanes Pritchard and Nesbitt (right). Buffa report they based their reconstruction on Megalancosaurus, but nested Avicranium with Vallesaurus. That not good science. See figure 2 frame 3 for a reconstruction based on µCT scans and Vallesaurus.
To make matters even worse,
Buffa et al had no idea that reptiles divided into Lepidosauromorpha and Archosauromorpha in the Viséan (Early Carboniferous). They reported, “The Late Permian Epoch witnessed the origin of both archosauromorphs and lepidosauromorphs, which together make up the clade Sauria, or crown-group reptiles.” ‘Sauria’ means Buffa et al wrongly assumed Synapsida split off earlier. Synapsida are members of the Archosauromorpha in the LRT.
On a similar note:
Buffa et al had no idea that the diapsid-type skull evolved twice by convergence. Colleagues, put the past behind you. It’s time to get up-to-date. Add taxa to find this out for yourself. The LRT has been online for 13 years as of today.
Taxon exclusion pervaded their cherry-picked cladogram.
Buffa et al reported, “However, much remains unknown of the early history of trilophosaurids and drepanosauromorphs, and of the evolution of arboreality in Triassic archosauromorph reptiles.”
There is a reason for their lack of understanding. In the LRT trilophosaurids and drepanosauromorphs are both lepidosaurs, not archosauromorphs. AND they are not related to one another in the LRT.
Contra Buffa et al much IS known of the early history of trilophosaurids and drepanosauromorphs all the way back to EarlyCambrian fish and earlier worms. Buffa et al omitted the basalmost drepanosauromorph in the LRT, Jesairosaurus. Add taxa to find this out for yourself.
Figure 1. Avicranium from Pritchard and Nesbitt 2017, in situ, original reconstruction and revised with rostral restoration.
” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=584″ class=”size-full wp-image-30136″ src=”https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=584&h=501″ alt=”Figure 1. Avicranium from Pritchard and Nesbitt 2017, in situ, original reconstruction and revised with rostral restoration.” width=”584″ height=”501″ srcset=”https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=584&h=501 584w, https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=150&h=129 150w, https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif?w=300&h=257 300w, https://pterosaurheresies.files.wordpress.com/2018/03/avicranium-skull588.gif 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 2. Avicranium from Pritchard and Nesbitt 2017, in situ, original reconstruction and revised with rostral restoration based on its sister, Vallesaurus.
An earlier look at Avicranium
in 2018 offered a new reconstruction (Fig 2 frame 3) in which the most gracile portions of the skull were restored based on an LRT sister, Vallesaurus (Fig 5).
Figure 3. Cherry-picked cladogram from Buffa et al 2024.
” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=127″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=432″ class=”size-full wp-image-85977″ src=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=584&h=1384″ alt=”Figure 3. Cherry-picked cladogram from Buffa et al 2024. ” width=”584″ height=”1384″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=584&h=1384 584w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=63&h=150 63w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif?w=127&h=300 127w, https://pterosaurheresies.files.wordpress.com/2024/05/avicranium2024-cladogram588.gif 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 3. Cherry-picked cladogram from Buffa et al 2024, modified to fit. Here aquatic Claudiosaurus is basal to the ‘rib’ gliders. Red flag. Rhynchosauru are basal to proterosuchids. Red flag. Tanystropheids are basal to azhendohsaurs. Red flag. Here, following academic traditions, Buffa et al shuffled lepidosauromorphs between archosauromophs. Note the absence of pterosaurs from this study that includes Ornithodira. Note the absence of pterosaurs despite the appearance here of Ornithodira. This list of problems here goes on and on.
Was surprised to see the absence
of Drepanosaurus (Fig 5) n the LRT. So it was added (finally!), nesting between Hypuronector and the more derived taxa, like Megalancosaurus. No surprise there.
Following academically approved traditions
Buffa et al shuffled lepidosauromorphs between archosauromophs. Unfortunately they did not check their results. In Buffa et al aquatic Claudiosaurus is basal to the ‘rib’ gliders. Red flag. Herbivorous yhynchosaurs are basal to piscivorous proterosuchids. Red flag. Long-necked tanystropheids are basal to bulky azhendohsaurs. Red flag. They also recover Parareptilia and other invalid clades.
Figure 3. Drepanosaurids to scale. Gray areas are not to scale.
” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=100″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=340″ class=”size-full wp-image-85984″ src=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=584&h=1760″ alt=”Figure 3. Drepanosaurids to scale. Gray areas are not to scale.” width=”584″ height=”1760″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=584&h=1760 584w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=50&h=150 50w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg?w=100&h=300 100w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosaurid-phyogeny588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 4. Drepanosaurids to scale. Gray areas are not to scale. The skull of Avicranium should be based on the Bauplan of Vallesaurus.
Add taxa
to your own homebuilt LRT. Don’t borrow untested cladograms based on trust, no matter how academically approved they are. Don’t make unforced phylogenetic errors based on taxon exclusion. If you have to use the LRT like an index to check for taxon exclusion.
Figure 4. Subset of the LRT focusing on drepanosaurids and their relatives.
” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=124″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=424″ class=”size-full wp-image-85982″ src=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=584&h=1410″ alt=”Figure 4. Subset of the LRT focusing on drepanosaurids and their relatives.” width=”584″ height=”1410″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=584&h=1410 584w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=62&h=150 62w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg?w=124&h=300 124w, https://pterosaurheresies.files.wordpress.com/2024/05/drepanosauromorpha_clade588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 5. Subset of the LRT focusing on drepanosaurids and their relatives. Buffa et al recovered Trilophosaurus alongside the drepanosaurs. Here the two are not related except distantly. Buffa et al omitted Jesairosaurus.
Check your results
to make sure sister taxa look like they could have evolved from one another. Swimmers don’t often evolve into ‘rib’ gliders. Rhynchosaurs, with their bizarre dentition, are terminal taxa, not transitional to proterosuchids. That role belongs to similar protorosaurs.
Try to choose the correct Bauplan
based on phylogenetic analysis. Don’t cherry-pick another Bauplan like Buffa et al did. Choose the sister taxon, especially if you know the sister taxon.
The problem with the invalid clade, ‘Avicephala’
(in the Buffa et al headline) was reviewed here in 2021.
References
Buffa V, Frey E, Steyer J-S and Laurin M 2024. ‘Birds’ of two feathers: Avicranium renestoi and the paraphyly of bird-headed reptiles (Diapsida: ‘Avicephala’). Zoological Journal of the Linnean Society 2024, XX:1–25.
Pritchard AC and Nesbitt SJ 2017. A bird-like skull in a Triassic diapsid reptile increases heterogeneity of the morphological and phylogenetic radiation of Diapsida. Royal Society Open Science DOI: 10.1098/rsos.170499.
wiki/Vallesaurus
wiki/Avicranium
Source: https://pterosaurheresies.wordpress.com/2024/05/14/avicranium-2024-mistakes-galore/
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