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

Vertebrate 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.