Morphometric materials for analyzing Eulipotyphlans across the Paleocene-Eocene-Thermal Maximum

Interpreting the impact of climate change on vertebrates in the fossil
record can be complicated by the effects of potential biotic drivers on
morphological patterns observed in taxa. One promising area where this
impact can be assessed is a high-resolution terrestrial record from the
Bighorn Basin, Wyoming, that corresponds to the Paleocene-Eocene Thermal
Maximum (PETM), a geologically rapid (~170 ky) interval of sustained
temperature and aridity shifts about 56 million years ago. The PETM has
been extensively studied, but different lines of research have not yet
been brought together to compare the timing of shifts in abiotic drivers
that include temperature and aridity proxies, and those of biotic drivers,
measured through changes in floral and faunal assemblages, to the timing
of morphological change within mammalian species lineages. We used a suite
of morphometric tools to document morphological changes in molar-crown
morphology of three lineages of stem erinaceid eulipotyphlans. We then
compared the timing of morphological change to that of both abiotic and
other biotic records through the PETM. In all three species lineages, we
failed to recover any significant changes in tooth crown shape or size
within the PETM. These results contrast with those documented previously
for lineages of medium-sized mammals, which show significant dwarfing
within the PETM. Our results suggest that biotic drivers such as shifts in
community composition may have also played an important role in shaping
species-level patterns during this dynamic interval in earth history.