SVP 2025 abstracts of interest 1

Figure 1. Dimorphodon macronyx and D. weintraubi, an anurognathid larger than its namesake. ” data-image-caption=”

Figure 1. Dimorphodon macronyx and D. weintraubi, an anurognathid larger than its namesake.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg?w=223″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg?w=584″ class=”wp-image-2727 size-full” src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg” alt=”Figure 1. Dimorphodon macronyx and D. weintraubi, an anurognathid larger than its namesake.” width=”588″ height=”791″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg 588w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg?w=112&h=150 112w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/11/two-dimorphodons.jpg?w=223&h=300 223w” sizes=”(max-width: 588px) 100vw, 588px” />

Figure 1. Large anurognathids and their typical-sized sisters. Here the IVPP embryo enlarged to adult size is larger than D. weintraubi and both are much larger than more typical basal anurognathids, Mesadactylus and MCSNB 8950.

The second species of Dimorphodon
Andres et al (p80) took another look at Dimorphodon weintraubi (Figs 1, 2). “The holoytpe is well preserved, and includes the posterior portion of the skull (including endocast), four cervical vertebrae, pectoral girdles, partial left and nearly complete right wing, and the right ankle and foot. Unusual for pterosaurs, it is three-dimensionally preserved with robust sturdy bones.”

“Dimorphodon weintraubi has been proposed to be a dimorphodontid, sister group to the Anurognathidae, or sister group to all pterosaurs but the Dimorphodontia. Phylogenetic analysis confirms that D. weintraubi is a later-branching member of an expanded Dimorphodontia with six Late Triassic to Middle Jurassic species: Parapsicephalus purdoni, D. macronyx and weintraubi, Rhamphinion jenkinsi, Allkaruen koi, and Caelestiventus hanseni.”

In the large pterosaur tree (LPT, 268 taxa) Parapsicephalus = Dorygnathus purdoni is transitional between dorygnathids and ctenochasmatids (Peters 2007), Alkaruen is close to the ctenochasmatid, Pterodaustro and anurognathids are small derived dimorphodontids, with one exception: the IVPP V13758 embryo is as large as a series of adult anurognathids and thus would have been a giant 8x larger as an adult. Dimorphodon weintraubi is the second largest anurognathid. In 1998 the foot of D weintraubi made the cover of Naure (Clark et al 1998) when they mistakenly decided that this taxon was flat-footed because the metatarsophalangeal joints were flat, not round. Details here.

Ironically authors who include scrappy fossils, like Rhamphinion = (the back of a braincase), don’t include more complete fossils (see the LPT). Not sure their reason for that.

‘Difficult’ nodes in placental mammal phylogeny and the timescale of mammal evolution
Beck (p108) trusts genomic studies form 20 years ago, but finds supraordinal nodes “remarkably difficult to resolve, even with very large ‘phylogenomic’ datasets.”

Resolution comes from omitting genomic data and allowing placentals to develop by convergence three times, according to the LRT, which tests traits only.

“Analysis of a large (130 taxa, 422 characters) morphological matrix of eutherians
using improved phylogenetic methods (including character ordering, molecularinformed
homoplasy partitioning, and Bayesian skyline tip-dating) confirms that no Cretaceous
eutherian is supported as a member of crowngroup Placentalia.”

The LRT employs 620 synapsid taxa and half as many characters. More taxa and fewer genes will likely help this study resolve itself.

Figure 1. Toothless Early Cretaceous Archaeorhynchus is the last common ancestor of all extant birds in the LRT. ” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg?w=275″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg?w=584″ class=”size-full wp-image-64004″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg” alt=”Figure 1. Toothless Early Cretaceous Archaeorhynchus is the last common ancestor of all extant birds in the LRT.” width=”584″ height=”637″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg?w=584&h=637 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg?w=138&h=150 138w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg?w=275&h=300 275w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2022/01/archaeorhynchus-juvenile-graphic588-1.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 2. Toothless Early Cretaceous Archaeorhynchus is the last common ancestor of all extant birds in the LRT.

A phylogenetic plesiomorphy zone obscures
the early evolutionary history of crown birds.
Benito et al (p112) reported, “Neornithes (the bird crown group) originated during the Late Cretaceous, yet their fossil record predating the end-Cretaceous mass extinction is extremely scarce.”

By contrast, in the LRT Early Cretaceous Archaeorhynchus (Fig 2) is the last common ancestor of all crown birds.

The authors mistakenly accept the genomic clade “Galloanserae”.

“Recent insights on the ancestral crown bird palate suggest that a galloanseran-like palate may be ancestral for Neornithes.”

By contrast, in the LRT the first dichotomy splits palaeognathids from neognathids, as was once taught.

References
SVP 2025 Program Guide.