Mammals across K/Pg boundary in northeastern Montana

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

A new non-dino paper:


Gregory P. Wilson (2013)
Mammals across the K/Pg boundary in northeastern Montana, U.S.A.:
dental morphology and body-size patterns reveal extinction selectivity
and immigrant-fueled ecospace filling.
Paleobiology 39(3):429-469. 2013
doi: http://dx.doi.org/10.1666/12041
http://www.bioone.org/doi/abs/10.1666/12041

The Cretaceous/Tertiary (K/Pg) mass extinction has long been viewed as
a pivotal event in mammalian evolutionary history, in which the
extinction of non-avian dinosaurs allowed mammals to rapidly expand
from small-bodied, generalized insectivores to a wide array of body
sizes and ecological specializations. Many studies have used global-
or continental-scale taxonomic databases to analyze this event on
coarse temporal scales, but few studies have documented morphological
diversity of mammalian paleocommunities on fine spatiotemporal scales
in order to examine ecomorphological selectivity and ecospace filling
across this critical transition. Focusing on well-sampled and
temporally well-constrained mammalian faunas across the K/Pg boundary
in northeastern Montana, I quantified dental-shape disparity and
morphospace occupancy via landmark- and semilandmark-based geometric
morphometrics and mean body size, body-size disparity, and body-size
structure via body-mass estimates.

My results reveal several key findings: (1) latest Cretaceous mammals,
particularly metatherians and multituberculates, had a greater
ecomorphological diversity than is generally appreciated, occupying
regions of the morphospace that are interpreted as strict carnivory,
plant-dominated omnivory, and herbivory; (2) the decline in
dental-shape disparity and body-size disparity across the K/Pg
boundary shows a pattern of constructive extinction selectivity
against larger-bodied dietary specialists, particularly strict
carnivores and taxa with plant-based diets, that suggests the kill
mechanism was related to depressed primary productivity rather than a
globally instantaneous event; (3) the ecomorphological recovery in the
earliest Paleocene was fueled by immigrants, namely three
multituberculate families (taeniolabidids, microcosmodontids,
eucosmodontids) and to a lesser extent archaic ungulates; and (4)
despite immediate increases in the taxonomic richness of eutherians,
their much-celebrated post-K/Pg ecomorphological expansion had a
slower start than is generally perceived and most likely only began
400,000 to 1 million years after the extinction event.