Fluvial processes and vertebrate taphonomy: the upper cretaceous Judith River formation, South-Central dinosaur Provincial Park, Alberta, Canada

AbstractThe Careless Creek Quarry (CCQ) is a multitaxic bonebed in the Campanian Judith River Formation of south-central Montana (USA) that produced a diverse assemblage of vertebrates, including several dinosaurian clades. We describe the morphology of the CCQ hadrosaurid material and reevaluate its taxonomic affinities. Our osteological comparative observations, coupled with maximum parsimony phylogenetic analyses, indicate that the majority of the hadrosaurid material is referable to kritosaurin saurolophines. Only an ischium is unambiguously referable to Lambeosaurinae. Most of the kritosaurin specimens likely represent a taxon that forms a polytomy with species of Gryposaurus and Rhinorex condrupus Gates and Sheetz, 2015. This form may represent individuals of either G. latidens Horner, 1992 or G. notabilis Lambe, 1914, or a new species cogeneric or not with Gryposaurus. The juvenile material exemplifies several patterns of mandibular and appendicular osteological variation previously observed in other hadrosaurids. However, it also shows some departures from the common trends, supporting the fact that not all skeletal growth changes can be generalized to all hadrosaurids.

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The smallest ceratopsid skull–Judith River Formation of Alberta

Canadian Journal of Earth Sciences ◽

10.1139/e88-090 ◽

1988 ◽

Vol 25 (6) ◽

pp. 926-930 ◽

Cited By ~ 19

Author(s):

Peter Dodson ◽

Philip J. Currie

Keyword(s):

Upper Cretaceous ◽

Adult Size ◽

Allometric Growth ◽

Judith River Formation ◽

Provincial Park

A partial skull found at Dinosaur Provincial Park, Alberta, in Upper Cretaceous (Campanian) sediments is the smallest specimen of a ceratopsid ever found, belonging to an animal about 1.1 m long. It represents an animal probably less than 2 years old, one fifth of its adult size. The shape of the squamosal and the thinness of the parietal suggest a tentative referral to Monoclonius. Strong positive allometric growth of the parietal fenestra is inferred.

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The significance of vertebrate microfossil size and shape distributions for faunal abundance reconstructions: a Late Cretaceous example

Paleobiology ◽

10.1017/s0094837300016377 ◽

1996 ◽

Vol 22 (3) ◽

pp. 422-435 ◽

Cited By ~ 28

Author(s):

Richard W. Blob ◽

Anthony R. Fiorillo

Keyword(s):

Late Cretaceous ◽

Upper Cretaceous ◽

Sedimentary Facies ◽

Size And Shape ◽

South Central ◽

Faunal Abundance ◽

Central Montana ◽

Judith River Formation ◽

Shape Data

Faunal abundance and fossil size and shape data from microvertebrate localities in the Upper Cretaceous Judith River Formation of south-central Montana illustrate that even when located in similar sedimentary facies, concentrations of vertebrate microfossils may exhibit strikingly different taphonomic profiles. Degrees of microfossil size and shape sorting may vary even among sites from the same sedimentary facies. In some instances, such variations may make it impossible to disregard taphonomic causes for differences sites exhibit in paleofaunal abundances. To limit the possibility that taphonomically generated faunal differences might be mistaken for true differences in paleoecology, comparisons of paleofaunal abundances should be restricted to microvertebrate sites both from similar sedimentary facies and with similar profiles of fossil sizes and shapes.

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CAPTURING A LATE CRETACEOUS PALEOFAUNA: A NEW VERTEBRATE MICROFOSSIL BONEBED IN THE UPPER CRETACEOUS (CAMPANIAN) JUDITH RIVER FORMATION, MONTANA

10.1130/abs/2019am-335766 ◽

2019 ◽

Author(s):

Gabriela E. Roat ◽

◽

Sedalia P. Gomez ◽

Sun M. Tun ◽

Katherine I. Irving ◽

...

Keyword(s):

Late Cretaceous ◽

Upper Cretaceous ◽

Judith River Formation

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Sierraceratops turneri, a new chasmosaurine ceratopsid from the Hall Lake Formation (Upper Cretaceous) of south-central New Mexico

Cretaceous Research ◽

10.1016/j.cretres.2021.105034 ◽

2021 ◽

pp. 105034

Author(s):

Sebastian G. Dalman ◽

Spencer G. Lucas ◽

Steven E. Jasinski ◽

Nicholas R. Longrich

Keyword(s):

New Mexico ◽

Upper Cretaceous ◽

South Central ◽

Lake Formation

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Isotaphonomy in concept and practice: an exploration of vertebrate microfossil bonebeds in the Upper Cretaceous (Campanian) Judith River Formation, north-central Montana

Paleobiology ◽

10.1017/pab.2016.37 ◽

2017 ◽

Vol 43 (2) ◽

pp. 248-273 ◽

Cited By ~ 7

Author(s):

Raymond R. Rogers ◽

Matthew T. Carrano ◽

Kristina A. Curry Rogers ◽

Magaly Perez ◽

Anik K. Regan

Keyword(s):

Upper Cretaceous ◽

Statistical Tests ◽

Sampling Strategies ◽

North Central ◽

Wetland Ecosystems ◽

Future Studies ◽

Size And Shape ◽

Definition Of ◽

Central Montana ◽

Judith River Formation

AbstractVertebrate microfossil bonebeds (VMBs)—localized concentrations of small resilient vertebrate hard parts—are commonly studied to recover otherwise rarely found small-bodied taxa, and to document relative taxonomic abundance and species richness in ancient vertebrate communities. Analyses of taphonomic comparability among VMBs have often found significant differences in size and shape distributions, and thus considered them to be non-isotaphonomic. Such outcomes of “strict” statistical tests of isotaphonomy suggest discouraging limits on the potential for broad, comparative paleoecological reconstruction using VMBs. Yet it is not surprising that sensitive statistical tests highlight variations among VMB sites, especially given the general lack of clarity with regard to the definition of “strict” isotaphonomic comparability. We rigorously sampled and compared six VMB localities representing two distinct paleoenvironments (channel and pond/lake) of the Upper Cretaceous Judith River Formation to evaluate biases related to sampling strategies and depositional context. Few defining distinctions in bioclast size and shape are evident in surface collections, and most site-to-site comparisons of sieved collections are indistinguishable (p≤0.003). These results provide a strong case for taphonomic equivalence among the majority of Judith River VMBs, and bode well for future studies of paleoecology, particularly in relation to investigations of faunal membership and community structure in Late Cretaceous wetland ecosystems. The taphonomic comparability of pond/lake and channel-hosted VMBs in the Judith River Formation is also consistent with a formative model that contends that channel-hosted VMBs were reworked from pre-existing pond/lake assemblages, and thus share taphonomic history.

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