Phytosaur post-dentary jaw region systematic utility (free pdf)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Free pdf:

Víctor López-Rojas, Miguel Moreno-Azanza & Eduardo Puértolas-Pascual (2025)
Systematic utility of the phytosaur post-dentary mandibular region
Papers in Palaeontology 11(6): e70045
doi: https://doi.org/10.1002/spp2.70045
https://onlinelibrary.wiley.com/doi/10.1002/spp2.70045

Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.70045


Phytosaurs, crocodile-like archosaurs from the Late Triassic, are known for their unique skull shape, whereas their mandibles are poorly studied. Two-dimensional (2D) geometric morphometric (GM) analysis is commonly used on dinosaurs and mammals. We applied this technique for the first time to the study of phytosaur mandibles to identify and quantify morphological differences outside the skull for use in phylogenetic analysis. The 2D GM analysis showed that the dorsal shape of the surangular had significant phylogenetic utility. This led to the reformulation of two characters (shape of the dorsal margin of the surangular, and shape of the retroarticular process) and the creation of four more new characters: shape of the ventral margin of the angular, dorsoventral height of the external mandibular fenestra, suture between the dentary and surangular, and the dorsal margin transition angle between the dentary and the surangular. Furthermore, three of these were identified as synapomorphies for the clade Leptosuchomorpha. To test the hypothesis that the mandible is taxonomically relevant, we ran a second analysis including two problematic, mandible specimens: NOVA-FCT-DCT 5396 (Silves Group, Portugal); and NMMNHS P-4256 (Bull Canyon Formation, New Mexico; which has been referred to Machaeroprosopus and Redondasaurus in previous studies). The analysis provided better resolution for these indeterminate specimens, suggesting that NOVA-FCT-DCT 5396 is Angistorhinus cf. talainti, and NMMNHS P-4256 is cf. Machaeroprosopus (Mystriosuchini).

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