Monday, 24 November 2025

Athenar bermani: A new species of Diplodocoid Sauropod from the Late Jurassic Morrison Formation of Dinosaur National Monument, Utah.

In 1913 prolific American fossil hunter Earl Douglass excavated a Sauropod braincase and partial skull roof from the Carnegie Quarry site at Dinosaur National Monument in Utah. This made its way to the collection of the Carnegie Museum in Pittsburgh, where it was given the specimen number CM 26552, and was largely forgotten for half a century (to give some context, Douglass excavated over 300 tonnes of material, including many complete skeletons of Jurassic Dinosaurs such as Diplodocus, Dryosaurus, Stegosaurus, Barosaurus, Camarasaurus, and Brontosaurus, which may have left museum staff a bit busy).

In 1978, palaeontologists David Berman and John McIntosh published a study in which they revised the genera Diplodocus and Camarasaurus, in which they assigned the specimen CM 26552 to Diplodocus. However, since that time our understanding of Sauropods as a group has developed significantly, notably in that proportional differences, which could change significantly as Sauropods grew, are no longer given the same emphasis, with modern palaeontologists instead placing more emphasis on character states (discrete features which can be present or absent).

In a paper published in the journal Palaeontologica Electronica in October 2025, John Whitlock of the Department of Science and Mathematics at Mount Aloysius College and the Section of Vertebrate Paleontology at the Carnegie Museum of Natural HistoryJuan Pablo Garderes and Pablo Gallina of the Consejo Nacional de Investigaciones Científicas y Técnicas, the Argentina and Fundación de Historia Natural Félix de Azara, and the Centro de Ciencias Naturales, Ambientales y Antropológicas at Universidad Maimónides, and Matthew Lamanna, also of the Section of Vertebrate Paleontology at the Carnegie Museum of Natural History, formally redescribe specimen CM 26552, assigning it to a new species and genus.

Based upon their inspection of CM 26552, Whitlock et al. conclude that it should be placed in the Dicraeosauria, a sub-group of the Diplodocidae, the skulls of which can be determined by (1) the presence of postparietal and frontoparietal fenestrae, (2) the exclusion of the basioccipital from the dorsal margin of the occipital condyle by the exoccipitals, (3) the presence of a distinct prong on the squamosal, (4) the contribution of the frontal to the margin of the supratemporal fenestra, (5) an expanded crista prootica, (6) a free dorsal margin of the antotic process, (7) the presence of a “shelf” overhanging the foramen for the trigeminal (V) nerve, and (8) the flat distal margin of the paroccipital process.

Braincase CM 26552 in anterior (A), (C) and posterior (B), (D) views. Abbreviations: BO, basioccipital; BS, basisphenoid; BT, basal tubera; CPR, crista prootica; EO-OP, exoccipitalopisthotic; F, frontal; LS, laterosphenoid; OS, orbitosphenoid; P, parietal; PO, postorbital; POP, paroccipital process; PR, prootic; S, shelf overhanging the opening for cranial nerve V; SOC, supraoccipital; SQ, squamosal; I, opening for cranial nerve I; II, opening for cranial nerve II; IV, opening for cranial nerve IV; V, opening for cranial nerve V. Whitlock et al. (2025).

Within that group, however, specimen CM 26552 shows a unique combination of features, not seen in any other genera, plus one unique character state,  the presence of a ‘tooth’ in the parietal/opisthotic suture, which has not previously been seen. For this reason, Whitlock et al. assign CM 26552 to a new species and genus, under the name Athenar bermani, where 'Athenar' honours the musician Athenar, 'for whom no better palaeontological comparison exists than a broken skull', and 'bermani' honours palaeontologist David Berman, who did so much of the fundamental modern work on Diplodocoid skulls at Carnegie Museum of Natural History and was responsible for the initial description of the specimen. 

Given the limited material available, no size estimate is made for Athenar bermani, although Whitlock et al. note that it appears to have been larger than the mature Diplodocus CM 11161, but shows incomplete fusion of many of the sutures of the braincase, suggesting that the specimen was a subadult at its time of death. 

See also...