10.5061/DRYAD.MF19Q
Anderson, Evan P.
University of Colorado Boulder
Smith, Dena M.
University of Colorado Boulder
Data from: The same picture through different lenses: quantifying the
effects of two preservation pathways on Green River Formation insects
Dryad
dataset
2016
Lacustrine Deposits
Early Diagenesis
Keroginization
mineralization
Preservation Quality Analysis
Eocene
Diptera
2016-07-06T13:40:12Z
2016-07-06T13:40:12Z
en
https://doi.org/10.1017/pab.2016.29
113243 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Insects in the fossil record are generally preserved in lacustrine shales
or in amber. For those in lacustrine shales, preservation is usually via
keroginization or mineralization. Given the extended period of microbial
decay required to generate ions for mineralization, there is a predicted
inherent bias toward lower preservation quality for this pathway by most
taphonomic indices compared with keroginization. This study tests this
hypothesis by comparing multiple measures of preservation quality between
sites with similar sedimentology in the Eocene Green River Formation of
Colorado. Here, insects are either mineralized in iron oxides (likely
after pyrite) at the Paleoburn site or keroginized at the Anvil Points
site. Generally, the prediction that keroginization preserves soft-bodied
fossils with higher preservational quality than mineralization is
affirmed, but with some caveats. Beetles, known for their robust cuticles,
are proportionately more abundant at the Paleoburn site, but eight of the
nine orders recorded are shared between sites. As predicted, insects show
lower preservation fidelity at the Paleoburn site, but they also show
higher degrees of disarticulation. This second bias should be acquired
primarily during the biostratinomy stage, and not early diagenesis.
Nonetheless, higher-energy biostratinomic conditions may be compatible
with taphonomic conditions that promote mineralization over
keroginization. Comparing the inherent taphonomic bias of different
preservation pathways is often difficult, since fossil deposits may be
preserved millions of years or thousands of kilometers apart. By studying
two different preservation pathways of insects within the same formation,
we can affirm that keroginization does indeed preserve recalcitrant
organic matter with higher quality than pyritization or iron-oxide
mineralization. Additionally, some guidelines can be proposed concerning
the body parts and taxa that can be compared, and for what purpose, when
contrasting mineralized and keroginized soft-bodied deposits.
Anderson, E. P., and Smith, D. M. Supplementary TableThis table contains
all the raw preservation quality data collected from the Paleoburn and
Anvil Points sites. Tallies of insect order abundance, preservation
fidelity scores, morphology quantity counts, individual morphological
component and insect body completeness articulation counts, and the
statistical tests analyzing these preservation quality measures are also
included. Finally, measurements of insect body areas are included, as well
as the statistical tests that analyze them.EPAaDSSupplementary_Table.xlsx
Colorado
Piceance Creek Basin