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[dinosaur] Late Cretaceous stratigraphy: please review and comment
Posting message for Denver Fowler. Please direct responses directly to him at firstname.lastname@example.org
Hi Everyone,I have recently uploaded the first version of my strat chart project to PeerJ preprints.Denver W. Fowler (2016) A new correlation of the Cretaceous formations of the Western Interior of the United States, I: Santonian-Maastrichtian formations and dinosaur biostratigraphy.(see abstract at bottom)https://peerj.com/preprints/2554v1/The strat chart project correlates the major terrestrial geological formations of the US Western Interior (most notably, those that contain dinosaur fossils), and includes over 200 recalibrated radiometric dates. The chart corrects errors in previous correlations and recalibrations and should be the most accurate and up to date correlation available. This is a considerable amount of work and should replace all other currently available correlations and recalibrations.DINOSAURS: The chart also includes consequent plots of the known stratigraphic ranges of dinosaur taxa. This initial version of the chart includes most ornithischian clades, but I have data on pretty much all other clades ready for inclusion in subsequent versions (along with mammals, birds, crocs etc; I intend to add everything eventually).The manuscript has been simultaneously submitted for publication at an open-access journal, but given the huge scope of the document I am hoping to assist the "official" reviews by inviting knowledgeable people to comment directly at the PeerJ Preprint site. Perhaps you are an expert on a given clade or formation and you notice that I am missing a reference etc. Please leave a comment if so!Please note that the chart itself takes the form of an excel sheet which is provided as Supplementary table S1. This has hundreds of pop-up notes embedded in the excel sheet which give justification for the correlation or plot. More information on the formatting etc is given in the main manuscript, which has some methods and discussion, but the S1 chart is the main meat of the project.Please feel free to share this email with any interested individuals, or repost to an appropriate server / email list.Thank you all!Denver Fowler----------------------------------
Denver Fowler, Ph.D
Curator, Dinosaur Museum @ Dickinson Museums Center
& Fowler Paleontology & Geology Consulting
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.