Bajadasaurus (dicraeosaurid) head and eye musculature + dacentrurine stegosaurs in North America (free pdfs)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New papers:

Free pdf:

Juan Pablo Garderes, Néstor Toledo, John Andrew Whitlock, Mariano Militello & Pablo Ariel Gallina (2026)
Head, skull–neck and extrinsic eye musculature of the dicraeosaurid sauropod Bajadasaurus pronuspinax
Musculatura de la cabeza, cabeza-cuello y ocular extrínseca del saurópodo dicraeosáurido Bajadasaurus pronuspinax
Publicación Electrónica de la Asociación Paleontológica Argentina 26(1): 80–112
DOI: https://doi.org/10.5710/PEAPA.11.11.2025.553
https://peapaleontologica.org.ar/index.php/peapa/article/view/553

Free pdf:
https://peapaleontologica.org.ar/index.php/peapa/article/view/553/941


Cranial muscles perform important roles triggering diverse paleobiological faculties, such as feeding, communication, alert postures, etc. Within Sauropoda, a clade with high specializations in skull architectures, and several partially complete skulls recovered, detailed reconstructions of the cranial muscles are mainly limited to two of the most famous taxa of the clade: Diplodocus and Camarasaurus. The cranial musculature for Dicraeosauridae, a minor group within the clade, has been gingerly described, based on the few suitable specimens. Herein, the craniomandibular, extrinsic eye, and cervicocranial musculatures of Bajadasaurus pronuspinax are inferred, resulting in the first detailed reconstruction for Dicraeosauridae on these muscular groups, and these are compared with previous inferences in Dicraeosauridae and with other Sauropoda and non-avian dinosaurs. The musculature of Bajadasaurus shows a shift of angle in the temporal musculature when passing through the inferior temporal window (probably indicating the presence of a cartilage for support), an important role of the orbitotemporal muscles in a hypothetical cranial kinesis (which, if true, would allow pseudo-palinal movements in a rostral direction during the feeding process), an avian-like configuration of the eye muscles, and high lateroflexor moment arms for the skull-neck complex. Dicraeosauridae show clear osteological correlates for a high number of the craniomandibular and cervicocranial muscles, albeit some of these correlates might not be exclusively dedicated for musculature, and could be indicating the presence of alternative soft tissues.

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Free pdf:

Francisco Costa (2026)
Dacentrurine Stegosaurs in North America: New Occurrences from the Upper Jurassic of USA (Morrison Formation)
Diversity 18(3): 143
doi: https://doi.org/10.3390/d18030143
https://www.mdpi.com/1424-2818/18/3/143


Dacentrurinae is a subclade within the iconic dinosaur group Stegosauria, first discovered in the late 19th century and characteristic of Late Jurassic Europe. The taxon “Alcovasaurus” longispinus (Wyoming, USA) has been recombined as the dacentrurine Miragaia longispinus, after comparisons with Miragaia longicollum (Portugal) found it closer to the latter than to the cohabiting Stegosaurus. This demonstrated that dacentrurines were also present in Late Jurassic North America and opened the possibility of more occurrences being found. After first-hand examination of various paleontological collections from the USA and reviews of the literature, at least five more occurrences of dacentrurines were identified, including four in the genus Miragaia. The material reviewed comprises one cervical plate, one dorsal vertebra, and three caudal spines from the Upper Jurassic Morrison Formation of Wyoming or Utah. The existing holotype material of M. longispinus was also analyzed here. These findings further support the theorized dinosaur faunal interchange between Europe and North America during the Late Jurassic and suggest that the presence of dacentrurine stegosaurs in Late Jurassic North America was not a rare accidental occurrence; rather, they were an established part of that ecosystem, likely more diverse and widespread than can currently be determined.

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