The Late Jurassic sauropod dinosaur ‘<i>Morosaurus’ agilis</i>Marsh, 1889 reexamined and reinterpreted as a dicraeosaurid

Whitlock, John A.; Mantilla, Jeffrey A. Wilson

doi:10.1080/02724634.2020.1780600

Cited by 24 publications

(37 citation statements)

References 71 publications

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“…CPOLs appear to be largely reconstructed along their ventral portions, but extend mainly vertically, forming the lateral margins of the posterior neural canal opening. The CPOL is conjoined with the PCDL along this section, as is the case in nearly all diplodocoids, including both species of Haplocanthosaurus [ 5 , 7 , 74 ] ( figure 6 ). The dorsal portion of the CPOL projects posterodorsally in lateral view, although this might have been distorted, and connects to the anterior end of the ventral surface of the postzygapophysis.…”

Section: Description and Comparisons Of Amphicoelias Altusmentioning

confidence: 99%

“…No POSL is present ventral to this convergence. Unlike diplodocids [ 7 , 51 , 74 ] ( figure 6 ), there are no posteroventrally opening fossae (pockets) on the posterior surface of the neural spine, close to its apex.…”

Section: Description and Comparisons Of Amphicoelias Altusmentioning

confidence: 99%

“…

Figure 15 Phylogenetic position of A. altus showing strict consensus trees of diplodocoid interrelationships based on Mannion et al . [ 50 ] with ( a ) EQW and ( b ) EIW, Whitlock & Wilson Mantilla [ 7 ] with ( c ) EQW and ( d ) EIW, and Xu et al . [ 92 ] with ( e ) EQW and ( f ) EIW.…”

Section: Description and Affinities Of Materials Previously Referred To Amphicoeliasmentioning

confidence: 99%

“…Scores for Amphicoelias in this data matrix are unchanged following our revision herein. The second data matrix is that of Whitlock & Wilson Mantilla [ 7 ], which focused on diplodocoid relationships. Amphicoelias was excluded from that version of the data matrix, but was included in previous iterations (e.g.…”

Section: Phylogenetic Position Of Amphicoelias Altusmentioning

confidence: 99%

“…[ 49 , 51 ]), in which it was consistently recovered as a non-diplodocimorph diplodocoid. It is rescored for the dataset of Whitlock & Wilson Mantilla [ 7 ]. The third data matrix is that of Xu et al .…”

Section: Phylogenetic Position Of Amphicoelias Altusmentioning

confidence: 99%

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Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA

2021

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Sauropod dinosaurs were an abundant and diverse component of the Upper Jurassic Morrison Formation of the USA, with 24 currently recognized species. However, some authors consider this high diversity to have been ecologically unviable and the validity of some species has been questioned, with suggestions that they represent growth series (ontogimorphs) of other species. Under this scenario, high sauropod diversity in the Late Jurassic of North America is greatly overestimated. One putative ontogimorph is the enigmatic diplodocoid Amphicoelias altus , which has been suggested to be synonymous with Diplodocus . Given that Amphicoelias was named first, it has priority and thus Diplodocus would become its junior synonym. Here, we provide a detailed re-description of A. altus in which we restrict it to the holotype individual and support its validity, based on three autapomorphies. Constraint analyses demonstrate that its phylogenetic position within Diplodocoidea is labile, but it seems unlikely that Amphicoelias is synonymous with Diplodocus . As such, our re-evaluation also leads us to retain Diplodocus as a distinct genus. There is no evidence to support the view that any of the currently recognized Morrison sauropod species are ontogimorphs. Available data indicate that sauropod anatomy did not dramatically alter once individuals approached maturity. Furthermore, subadult sauropod individuals are not prone to stemward slippage in phylogenetic analyses, casting doubt on the possibility that their taxonomic affinities are substantially misinterpreted. An anatomical feature can have both an ontogenetic and phylogenetic signature, but the former does not outweigh the latter when other characters overwhelmingly support the affinities of a taxon. Many Morrison Formation sauropods were spatio-temporally and/or ecologically separated from one another. Combined with the biases that cloud our reading of the fossil record, we contend that the number of sauropod dinosaur species in the Morrison Formation is currently likely to be underestimated, not overestimated.

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Section: Description and Comparisons Of Amphicoelias Altusmentioning

confidence: 99%

Section: Description and Comparisons Of Amphicoelias Altusmentioning

confidence: 99%

“…

Section: Description and Affinities Of Materials Previously Referred To Amphicoeliasmentioning

confidence: 99%

Section: Phylogenetic Position Of Amphicoelias Altusmentioning

confidence: 99%

Section: Phylogenetic Position Of Amphicoelias Altusmentioning

confidence: 99%

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Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA

2021

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Description of a new specimen of Haplocanthosaurus from the Dry Mesa Dinosaur Quarry

Boisvert,

Curtice,

Wedel

et al. 2024

The Anatomical Record

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A new specimen of Haplocanthosaurus is described based on bones excavated from the Late Jurassic Dry Mesa Dinosaur Quarry near Delta, Colorado. The specimen consists of seven dorsal vertebrae and a right tibia and is identified as Haplocanthosaurus based on the dorsally angled transverse processes, tall neural arch peduncles, low parapophyses relative to the diapophyses in the posterior dorsal vertebrae, and the robustness of the tibia combined with a greatly expanded distal articular surface. The discovery adds to our understanding of the biostratigraphy of Haplocanthosaurus, showing this genus is definitively present in the Brushy Basin Member of the Morrison Formation, and making this individual the geologically youngest Haplocanthosaurus specimen on the Colorado Plateau. The identification of this genus adds to the known diversity of sauropods at Dry Mesa Dinosaur Quarry (DMDQ), which is at least six distinct genera, making DMDQ the most diverse single locality of sauropods in the Morrison Formation and the world.

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Highly Specialized Diplodocoids: The Rebbachisauridae

Salgado

Gallina

Lerzo

2022

Springer Earth System Sciences

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The Late Jurassic sauropod dinosaur ‘Morosaurus’ agilisMarsh, 1889 reexamined and reinterpreted as a dicraeosaurid

Cited by 24 publications

References 71 publications

Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA

Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA

Description of a new specimen of Haplocanthosaurus from the Dry Mesa Dinosaur Quarry

Highly Specialized Diplodocoids: The Rebbachisauridae

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