UNIVERSITY PARK, Pa. — Kayla Irizarry, doctoral candidate in geosciences at Penn State, is using her Ford Foundation Predoctoral Fellowship to better understand what controlled diversity in Earth’s earliest complex ecosystems. Her research focuses on the Cambrian period, about 485 million to 541 million years ago, which was a prolific time of change in the history of life known as the "Cambrian Explosion."
“The Cambrian Explosion was a dramatic transition when simple, soft bodied animals gave way to animals with limbs, heads, hard skeletal parts and complex sensory organs like eyes,” Irizarry said.
However, in the middle and late Cambrian, species diversity tended to flatten out with high background extinction rates and frequent large extinction events. Irizarry’s research seeks to answer the question: Did fluctuating oxygen conditions control extinction and diversification during this diversity plateau in the latter half of the Cambrian?
“Nearly all animal phyla evolved during the Cambrian Explosion, but in the middle-to-late Cambrian, marine invertebrates experienced high extinction rates hypothesized to have been triggered by persistently low oxygen conditions in the ocean,” Irizarry said.
Irizarry said she wants to look at this question through both a geochemist lens and a paleontologist lens.
“Geochemists will look at the fluctuating oxygen conditions in the ocean, which have been identified by geochemistry, and say it probably affected the animals; and paleontologists will say that the fossil assemblages look like this so maybe this has something to do with the oxygen levels. Not enough researchers are playing both roles,” Irizarry said. “Few studies have combined geochemical and quantitative paleontological data to understand the mechanism by which low oxygen conditions affected marine invertebrate communities.”