SVP 2025 abstracts of interest 3
More SVP 2025 abstracts here.
This is part 3 of 10.
How many characters are needed to reconstruct a phylogeny?
Capobianco A (p159)
“Despite increased recent attention towards Bayesian phylogenetics and its applications in understanding macroevolutionary processes, it remains unclear how many discrete characters are needed to accurately estimate tree topologies in a Bayesian framework.”
Somewhere between 200 and 250 works for the large reptile tree (LRT, 238 multistate characters).
“This could be particularly relevant for morphological datasets used in phylogenetics, including the ones assembled to reconstruct the relationships of extinct organisms, as they usually consist of few dozens to few hundreds of characters—orders of magnitude smaller than most molecular datasets.”
And yet... doggone it… molecules deliver false positives – and cannot include fossils.
The key is, and always has been, having a wide gamut inclusion set of taxa. Academics need to focus on adding taxa. Not sure why they tend to avoid that. After all, we’re all trying to lump and separate taxa – not characters here.
“I designed a simulation study”
There’s a >REAL the LRT and the large pterosaur tree (LPT, 266 taxa, 183 characters). Why waste time with simulations when real phylogenetic problems are out there waiting to be confirmed, refuted and/or modified? While you’re at it, ask the paleontologists you know why they still don’t add enough taxa? Match the LRT and LPT taxon lists and report results. That’s the scientific method.
Figure 1. Mesopoma might be Mesopoma planti. (a) NHM P11656,
Chondrostean signal within the early actinopterygian record
Canon and Coates (p161)
“The early diversification of ray-finned fishes (Actinopterygii) remains largely unresolved;”
In the LRT the ray-finned fishes are strongly resolved = not perfectly, but nearly. So the authors’ opening statement has been falsified. If they refuse to add pertinent taxa and show they way they interpret each taxon (DGS colors), that’s a problem in academic elitism or lack of curiosity. Neither is part of the scientific method. The LRT has set the bar higher than academics have dealt with at present. It’s time for them to step up to the plate and add taxa.
“morphology-based phylogenies conflict with molecular results and fail to reliably place Paleozoic taxa.”
No problem in the LRT. Where ray-finned fishes had at least three convergent origins. The academically-trained authors seem to not know this. Adding taxa is simple. It just takes time.
“This phylogenetic underperformance may stem from incomplete anatomical descriptions, character definitions that fail to accommodate the full range of early morphological diversity, and overreliance on external features (e.g. scales, dermal bones) that are prone to homoplasy.”
Or taxon exclusion. Adding taxa helps. Too many taxa are better than too few.
“Here we sample four Carboniferous actinopterygians of varying size and body shape (Trawdenia planti, Nematoptychius greenocki, Elonichthys robisoni, and Chirodus granulosum) using high-resolution μCT to test for endoskeletal signal.”
Trawdenia is a close relative or synonym for Mesopoma (Fig 1) and they are close to Engraulis, the extant anchovy.
Nematoptychius has not yet been tested in the LRT. A UK museum blog reported, “Given that it’s fairly impossible to identify this specimen from the mould alone, I’m going to controversially trust the label information*.
Elonichthys robisoni has not been tested in the LRT, but two other Elonichthys species Fig 2 shows one of the two) have been tested. Online E robisoni seems to be represented by vague patches of scales equivalent to terrestrial roadkill in quality.
Chirodus = Cheirodus = Amphicentrum is a derived placoderm in the LRT.
The authors don’t seem to know this.
Figure 1. Two species of Elongichthys in ontogenetic series
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg?w=584″ class=”size-full wp-image-61530″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg” alt=”Figure 1. Two species of Elongichthys in ontogenetic series” width=”584″ height=”433″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg?w=584&h=433 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg?w=150&h=111 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg?w=300&h=222 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/elonichthys-peltigerus588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 2. Two species of Elongichthys in ontogenetic series
“Exploratory phylogenetic analyses recover Trawdenia planti as a stem-chondrostean.
The LRT does not recover a monophyletic clade Chondrostei. Traditional members are scattered around the the LRT.
Source: https://pterosaurheresies.wordpress.com/2025/11/17/svp-2025-abstracts-of-interest-3/
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