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Earthworms thrived after K/Pg extinction event



From: Ben Creisler
bcreisler@gmail.com

A new non-dino paper in PLoS ONE that may be interest:

Karen Chin, Dean Pearson & A. A. Ekdale (2013)
Fossil Worm Burrows Reveal Very Early Terrestrial Animal Activity and
Shed Light on Trophic Resources after the End-Cretaceous Mass
Extinction.
PLoS ONE 8(8): e70920.
doi:10.1371/journal.pone.0070920
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0070920


The widespread mass extinctions at the end of the Cretaceous caused
world-wide disruption of ecosystems, and faunal responses to the
one-two punch of severe environmental perturbation and ecosystem
collapse are still unclear. Here we report the discovery of in situ
terrestrial fossil burrows from just above the impact-defined
Cretaceous-Paleogene (K/Pg) boundary in southwestern North Dakota. The
crisscrossing networks of horizontal burrows occur at the interface of
a lignitic coal and silty sandstone, and reveal intense faunal
activity within centimeters of the boundary clay. Estimated rates of
sedimentation and coal formation suggest that the burrows were made
less than ten thousand years after the end-Cretaceous impact. The
burrow characteristics are most consistent with burrows of extant
earthworms. Moreover, the burrowing and detritivorous habits of these
annelids fit models that predict the trophic and sheltering lifestyles
of terrestrial animals that survived the K/Pg extinction event. In
turn, such detritus-eaters would have played a critical role in
supporting secondary consumers. Thus, some of the carnivorous
vertebrates that radiated after the K/Pg extinction may owe their
evolutionary success to thriving populations of earthworms.