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Rising mountains, cooling oceans prompted spread of invasive species 450 million years ago

Posted on August 22, 2013
Rising mountains, cooling oceans prompted spread of invasive species 450 million years ago

Rising mountains, cooling oceans prompted spread of invasive species 450 million years ago
This slab of rock contains fossils of invasive species that populated the continent of Laurentia 450 million years ago after a major ecological shift occurred. Ohio University geologists found that rising mountains and cooling oceans prompted the spread of these invasive species. Credit: Alycia Stigall

New Ohio University research suggests that the rise of an early phase of the Appalachian Mountains and cooling oceans allowed invasive species to upset the North American ecosystem 450 million years ago.

The study, published recently in the journal PLOS ONE, took a closer look at a dramatic ecological shift captured in the fossil record during the Ordovician period. Ohio University scientists argue that major geological developments triggered evolutionary changes in the ancient seas, which were dominated by organisms such as brachiopods, corals, trilobites and crinoids.

During this period, North America was part of an ancient continent called Laurentia that sat near the equator and had a tropical climate. Shifting of the Earth’s tectonic plates gave rise to the Taconic Mountains, which were forerunners of the Appalachian Mountains. The geological shift left a depression behind the mountain range, flooding the area with cool water from the surrounding deep ocean.

Scientists knew that there was a massive influx of invasive species into this ocean basin during this time period, but didn’t know where the invaders came from or how they got a foothold in the ecosystem, said Alycia Stigall, an Ohio University associate professor of geological sciences who co-authored the paper with former Ohio University graduate student David Wright, now a doctoral student at Ohio State University.

“The rocks of this time record a major oceanographic shift, pulse of mountain building and a change in evolutionary dynamics coincident with each other,” Stigall said. “We are interested in examining the interactions between these factors.”

Read more at: Phys.org

   
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