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

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 422-435 ◽  
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.

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

Paleobiology ◽  
2017 ◽  
Vol 43 (2) ◽  
pp. 248-273 ◽  
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.

The ‘duck-billed’ dinosaurs of Careless Creek (Upper Cretaceous of Montana, USA), with comments on hadrosaurid ontogeny

2016 ◽  
Vol 90 (1) ◽  
pp. 133-146 ◽  
Author(s):  
Albert Prieto-Márquez ◽  
Susana Gutarra
Keyword(s):  
New Species ◽  
Upper Cretaceous ◽  
Phylogenetic Analyses ◽  
Skeletal Growth ◽  
South Central ◽  
The Common ◽  
Growth Changes ◽  
Central Montana ◽  
Judith River Formation ◽  
A New Species

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.

scholarly journals A new hesperornithiform (Aves) specimen from the Late Cretaceous Canadian High Arctic with comments on high-latitude hesperornithiform diet

2016 ◽  
Vol 53 (12) ◽  
pp. 1476-1483 ◽  
Author(s):  
Laura E. Wilson ◽  
Karen Chin ◽  
Stephen L. Cumbaa
Keyword(s):  
Late Cretaceous ◽  
High Latitude ◽  
Upper Cretaceous ◽  
Current Knowledge ◽  
High Arctic ◽  
Time Of Death ◽  
Canadian High Arctic ◽  
Size And Shape ◽  
Devon Island ◽  
Paleoecological Reconstructions

Here we describe a new hesperornithiform specimen from the Upper Cretaceous Kanguk Formation of Devon Island, Nunavut, Canada. This specimen (NUVF 286) is referred to cf. Hesperornis sp. based on size and shape of femora and teeth preserved with other skeletal elements. Previous osteohistologic analyses indicate a subadult ontogenetic stage at the time of death. This new cf. Hesperornis specimen includes the first teeth associated with a high-latitude hesperornithiform, allowing for comments on the trophic behavior of these birds. Paleoecological reconstructions based on current knowledge of polar assemblages and comparisons to modern birds suggest that high-latitude hesperornithiform birds may have had more varied diets than previously assumed.

scholarly journals Crinoid diversity in the Upper Cretaceous Yezo Supergroup, Hokkaido, northern Japan*

Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 71-80
Author(s):  
AARON W. HUNTER
Keyword(s):  
Late Cretaceous ◽  
Deep Water ◽  
Upper Cretaceous ◽  
Outer Shelf ◽  
South Central ◽  
Sandstone Facies ◽  
Sandy Mudstone ◽  
Water Facies ◽  
Northern Japan ◽  
Mudstone Facies

New data, principally from ‘local’ encrinites in the Yezo Supergroup of Hokkaido, northern Japan, suggest that many relict ‘Jurassic-type faunas’ identified in Europe and central Japan might have persisted in the Late Cretaceous deep-water (> 100 m) muddy sandstone facies found throughout the island of Hokkaido. For example, Isocrinus and Balanocrinus occur in the outer shelf sandy mudstone facies of the Turonian-Coniacian Saku Formation and the Coniacian- Campanian Haborogawa Formation, of the Mikasa area (central Hokkaido), respectively. Isocrinus is also found in the Turonian-Coniacian deep-water siltstones and sandy siltstones of the Nishi-chirashinai Formation of the Nakagawa area (northern Hokkaido). In contrast, Isselicrinus, which belongs to ‘Late Cretaceous type-faunas’, occurs in the uppermost Creta­ceous (Campanian) outer shelf mudstone facies of the Upper Yezo Supergroup around Hobetsu (south-central Hokkaido). Although collections of crinoids from the chalks of northern Europe are themselves largely free from sampling biases, Cretaceous crinoid diversity data have been markedly influenced by fossils preserved in the relatively homogeneous chalk facies where the faunal differences between the deep-water Danish, English and north German chalks (> 250 m) and the shallow-water facies found around Maastricht, the Netherlands (< 50 m) are slight. The results of this preliminary report on the crinoid faunas of Hokkaido suggest that global crinoid diversity reported from the Upper Cretaceous might be influenced by sampling and facies biases.

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