Labocania aguillonae, new tyrannosaur species from Mexico + Allosaurus forelimb range

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New theropod papers:

Free pdf:

Labocania aguillonae sp. nov.

Héctor E. Rivera-Sylva and Nicholas R. Longrich (2024)
A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs
Fossil Studies 2(4): 245-272
doi: https://doi.org/10.3390/fossils2040012
https://www.mdpi.com/2813-6284/2/4/12

Zoobank urn:lsid:zoobank.org:pub:9A054D75-9B78-4B74-A6EC-7CE4E2CDB0DE.


The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (~72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated.

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Qingqing Liang, Lida Xing, Peter Lewis Falkingham, Chunlei Du, Kexiang Wen & Jin Lin (2024)
Forearm range of motion in Allosaurus fragilis (Dinosauria: Theropoda)
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2024.2403599
https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2403599



Forelimb bones of the Early Jurassic theropod Allosaurus fragilis were digitally manipulated based on three-dimensional (3D) digital models. Bony articular surface margins were used as limits to determine the range of motion (ROM) for each forelimb joint, and to test functional hypotheses of forelimb usage. We discuss the effects of palaeopathology at the right shoulder joint on inferring ROM in the forelimb of Allosaurus. It is considered that the glenoid aberration of this sub-adult specimen occurred in early ontogeny and lasted for a long period of time, affecting to varying degrees the development of the whole right arm (but not the manus). The relatively large ranges of extension and flexion of manual joints indicate well grasping ability consistent with early-diverging theropods. The limited ROM of the shoulder joints of Allosaurus suggests that the forelimbs were predominantly prey-acquiring but could go no further forward, indicating that the first contact with prey was made by the mouth. The manus could assist in grasping prey on the chest or below the neck or hooking objects.

[Ben Creisler]

A new video:

Labocania aguillonae, a new tyrannosaur from Coahuila, Mexico
Nick Longrich (video)
22 min.

https://www.youtube.com/watch?v=wF89nCpQPwU