Supplemental Materials: Early Miocene land mammals and chronology of the Belgrade Formation, eastern North Carolina
Data files
Oct 13, 2025 version files 257.26 KB
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Belgrade_R_Script.R
1.32 KB
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Belgrade_Raw_Sr_Data_Final_10.12.2025.csv
10.42 KB
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Belgrade_Supplementary_Materials_Updated_10.10.2025.pdf
242.74 KB
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README.md
2.78 KB
Abstract
Early Miocene land mammals from eastern North America are exceedingly rare. Over the past several decades, a small but significant vertebrate fauna has been recovered by paleontologists and citizen scientists from the Belgrade Formation at the Martin Marietta Belgrade Quarry in eastern North Carolina. This assemblage has 12 land mammal taxa, including beaver (Castoridae), stem lagomorph, carnivorans (Mustelidae, Ailuridae), horses (Equidae), rhinoceros (Rhinocerotidae), tapir (Tapiridae), peccary (Tayassuidae), anthracothere (Anthracotheriidae), entelodont (Entelodontidae), and protoceratid (Protoceratidae). Taken together, the biochronology of this Maysville Local Fauna indicates a late Arikareean (Ar3/Ar4) to early Hemingfordian (He1) North American Land Mammal Age (NALMA). This interval, which includes the Runningwater Chronofauna, documents numerous important Holarctic immigrants, including Amphictis, Craterogale, and cf. Menoceras found at this locality. Strontium isotope stratigraphy (SIS) of shark teeth collected in situ from the Belgrade Formation yields an age of 21.4 + 0.13 Ma, which validates the age of interbedded land mammals within this unit. It is also consistent with the late Arikareean (Ar3/Ar4) biochronology and Aquitanian Neogene marine stage. New SIS analyses of oysters (Striostrea gigantissima) and clams (Chione) from this mine, previously assigned to late Oligocene or late Miocene, are significantly older (28.0 + 0.22 Ma and 27.6 + 0.26 Ma, respectively) than the land mammals. Depending upon stratigraphic interpretations, these may confirm an older marine facies within the Belgrade Formation. This locality is thus important because of its marine and terrestrial tie-ins that facilitate intercalibration of both NALMAs and Cenozoic marine stages.
https://doi.org/10.5061/dryad.7h44j103k
Description of the data and file structure
These files contain the original data and analyses used for the interpretation of the strontium-ratio age determinations of Oligocene oysters and Miocene land mammals collected from the Martin Marietta Mine in Eastern North Carolina. These interpretations were based on previous references (cited in the main article) that developed a Neogene age curve based on unique variations in strontium ratios in the oceans at different times in the geological past.
This folder contains three files pertaining to the above-referenced paper:
1. Belgrade_Supplementary_Materials_Updated_10.10.2025.pdf
Statistical analyses used for the interpretation of the strontium-ratio age determinations.
2. Belgrade_R_Script.R
R code used for the statistical analyses presented in file 1 above.
3. Belgrade_Raw_Sr_Data_Final_10.12.2025.csv
Raw data Sr-isotope data produced on the mass spectrometer used for the statistical analyses presented in file 1 above.
Information about the analytical laboratory where these analyses were conducted can be found at:
These interpretations were based on previous references (cited in the main article) that developed a Neogene age curve based on unique variations in strontium ratios in the oceans at different times in the geological past.
Abbreviations
87/86, 86/88, 84/86, 84/86 are Sr (strontium) isotope ratios
corr, corrected for interference (87/86 Rb corr)
ANOVA, Analysis of Variance statistical test
Diff, difference
Exp., experimental
HSD, Honestly Significant Difference, Tukey statistical test
ID, internal laboratory sample identifier
Ma, megaannum, or millions of years ago on the geological time scale.
Max, Maximum
Min, minimum
NA, not applicable
NBS; National Bureau of Standards
P or p, probability
R; statistical computing software package
Rb; rubidium
SE, standard error
(sigma) σ error, standard deviation
Sr, strontium
(V), voltage
Code/software
Anything that can open CSV files, R scripts, and PDFs. The R code and scripts were developed here for the statistical analyses.
Access information
Other publicly accessible locations of the data:
- Not applicable
Data was derived from the following sources:
- As indicated above, based on independent laboratory analyses conducted during this study.
This dataset contains the individual analyses for the strontium-ratio age determinations using treated sample powders taken from Oligocene oysters and Miocene shark teeth collected from the Martin Marietta Belgrade Quarry in eastern North Carolina. It also includes the statistical tests and relevant R code that were used for the statistics.