Rhamphorhynchus skeletal allometry and flight capacity + Panzhousaurus (pachypleurosaur) osteology and phylogeny (free pdfs)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New papers:

Free pdf:

Gabriela Menezes Cerqueira, João Lucas Da Silva, Ingmar Werneburg, Mario Bronzati, Alex Sandro Schiller Aires, Felipe L. Pinheiro & Rodrigo Temp Müller (2026)
Allometric patterns in Rhamphorhynchus muensteri and their role in the paleoecology, life habits, and taxonomic framework of pterosaurs
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.70146
https://onlinelibrary.wiley.com/doi/10.1111/joa.70146

Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1111/joa.70146


Pterosaurs were the first vertebrates to achieve powered flight, a result of various unique anatomical adaptations, and significant morphological diversity throughout their evolutionary history. Although the pterosaurs body structure was specialized for powered flight, the clade exhibited great disparity from its origins, with later evolution giving rise to multiple phylogenetic lineages and a wide range of body sizes, from small forms such as Anurognathus ammoni to truly giant species like Quetzalcoatlus northropi. This variation led to distinct flight strategies within the group. Here, we assess allometry in the skeletal elements of Rhamphorhynchus muensteri in comparison with Eupterodactyloidea and Euctenochasmatia, examining their implications for paleoecology and flight capacity. The analysis included 127 specimens and assessed 13 skeletal variables using statistical methods, principal components analysis (PCA), and standardized major analysis (SMA). The results reveal differences in size–shape trajectories and functional adaptations related to activity flight. R. muensteri exhibits a trend of negative allometry (PCRW/body, humerus, radius/ulna, metacarpal IV, and femur), indicating distinct allometric scaling patterns and flight style. These patterns suggest behavior and ecological differences, as well differing flight capabilities between R. muensteri likely relied on active flapping flight interspersed with gliding, whereas other taxa may have exhibited greater migratory adaptations within Eupterodactyloidea, and a greater dependence on flapping flight in Euctenochasmatia. The negative allometry in R. muensteri suggests a flight style characterized by early flight capability (precocial flight), whereas Eupterodactyloidea showed positive allometry and Euctenochasmatia isometry. Additionally, the study highlights how allometric patterns influence pterosaur phylogeny, underscoring the importance of incorporating them into future analysis.

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Free pdf:

Feng-Ting Tan, Guang-Hui Xu & Qing-Hua Shang (2026)
Osteology and phylogeny of Panzhousaurus rotundirostris from the Middle Triassic (Anisian) of Guizhou Province, China, and implications for the origin of Keichousauridae (Pachypleurosauroidea, Eosauropterygia)
PeerJ 14: e21267
doi: https://doi.org/10.7717/peerj.21267
https://peerj.com/articles/21267/


Sauropterygia (including Placodontia and Eosauropterygia) is the most species-rich group of marine reptiles in the Mesozoic. Panzhousaurus rotundirostris is a rare eosauropterygian from the early Middle Triassic (Anisian) marine deposits of Panzhou, Guizhou Province, China. Until recently, P. rotundirostris has been known only by two specimens, and its phylogenetic position within Eosauropterygia remains much controversial. A taxonomic revision of P. rotundirostrisis is provided here based on a comparative study of the type material and a new, juvenile specimen from the same locality and horizon as the holotype. The revised description accommodates significant changes to the reconstruction of P. rotundirostris, including the skull roof, circumorbital bones, and jaws. The juvenile status of the new specimen is well confirmed by a series of features (e.g., smaller body size, relatively larger orbit, unfused neural arches, and fewer carpal ossifications and caudal ribs). The wealth of new anatomical data for this species has facilitated a phylogenetic analysis, the results of which recover Panzhousaurus as a keichousaurid and favour the sister group relationships between Keichousauridae and Pachypleurosauridae. The topology provides new insights into the origin and evolution of Keichousauridae, a major clade of eosauropterygian marine reptiles endemic in the Middle Triassic of China.

[Mickey Mortimer]

Er... can someone explain what Cerqueira et al.'s Figure 12 is trying to show? The orange bifurcating tree can't be a phylogram since Rhamphorhynchus and euctenochasmatians group to the exclusion of eupterodactyloids. Does lagerpetids' position on the far left and red color indicate very positive allometry? Does the unlabeled anurognathid silhouette in the upper left indicate anurognathids were also very positively allometric, or was it just added to fill an empty corner in the image since it's black and thus not a color they use to label allometry? Neither lagerpetids nor anurognathids are mentioned in the text.

For those curious, Yang et al. (2022) found anurognathids had negatively allometric skulls (unlike the three groups tested by Cerqueira et al.) and femora (like Rhamph), isometric radius/ulna (nega in Rhamph and Eucten), metacarpal IV, phalanx IV-1, IV-2 (all like Eucten) and tibia (like Rhamph), and positively allometric (like Rhamph and Eupter).

Mickey Mortimer

[Mickey Mortimer]

Oops, the last sentence should have read "...  and positively allometric phalanx IV-3 (like Rhamph and Eupter)."

Mickey Mortimer