A new correlation of the Cretaceous formations of the Western Interior of the United States, I: Santonian-Maastrichtian formations and dinosaur biostratigraphy
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Paleontology
- Keywords
- Biostratigraphy, Stratigraphy, Dinosaur, Cretaceous, 40Ar/39Ar, Radiometric dating
- Copyright
- © 2016 Fowler
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. A new correlation of the Cretaceous formations of the Western Interior of the United States, I: Santonian-Maastrichtian formations and dinosaur biostratigraphy. PeerJ Preprints 4:e2554v1 https://doi.org/10.7287/peerj.preprints.2554v1
Abstract
Late Cretaceous deposits of the North American Western Interior represent the best, if not only, opportunity to construct a high-resolution chronostratigraphic framework within which to conduct continental-scale geological and paleontological analyses. This is due to the serendipitous combination of large areas of outcrop, interfingering marine units with biostratigraphically informative fossils, and a consistent scattering of radiometric dates due to synorogenic volcanic activity. Accurate correlation is essential for testing a large number of current geological and paleobiological hypotheses; however, despite the large amount of data available, many published correlations suffer from inaccuracies or are simply based on outdated information.
Here I present a comprehensive high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. For the first time, nearly two hundred 40Ar / 39Ar radiometric dates are recalibrated to both current standard and decay constant pairings, correcting errors in previous recalibrations. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina Formations, Texas, and miscalculations in recently published analyses are corrected which in particular affects the relative age positions of the Belly River Group, Alberta; Judith River Group, Montana, Kaiparowits Formation, Utah, and Fruitland and Kirtland Formations, New Mexico.
This work represents the most extensive and accurate interbasinal correlation currently available for the North American Western Interior and should replace all previously published similar works and diagrams.
The stratigraphic ranges of selected dinosaur clades are plotted on the chronostratigraphic framework, typically forming stacks of short-duration species which do not overlap stratigraphically with preceding or succeeding forms. This is the expected pattern which is produced by an anagenetic mode of evolution, suggesting that true branching (speciation) events were rare and may have geographic significance. Purported north-south provinciality of dinosaurs is shown to be mostly an artifact of stratigraphic miscorrelation. Rapid stepwise acquisition of display characters in many dinosaur clades, in particular chasmosaurine ceratopsids, suggests that they may represent the highest resolution biostratigraphic markers to be used where radiometric dates are not available.
Author Comment
This preprint is being issued in order to solicit feedback and review of the extensive notes featured in the stratigraphic chart itself (supplemetary Table S1). The article itself has been simultaneously sent for formal publication, however the broad subject matter and large amount of data makes it challenging to find reviewers with expertise and time to cover the entire article. Thank you for your input, I look forward to your comments.
Supplemental Information
Stratigraphic Chart
Stratigraphic correlation of Upper Cretaceous terrestrial strata of the North American Western Interior from the Santonian through to the K-Pg boundary. Dinosaur taxon ranges plotted on to correlated geological units.
Recalibration Sheet
This sheet shows recalibration calculations for over 200 published Ar / Ar radiometric dates. These are recalibrated to the two current standards (Kuiper et al., 2008; Renne et al., 2011), shown on separate tabs. References are given within pop up notes for the respective recalibrated date(s).
References for Stratigraphic Chart
This text file lists all the references used in construction of the stratigraphic chart (Table S1).
