Researchers used Bayesian analysis to study the brachiopods’ decline and bivalves’ rise post-end-Permian extinction, finding bivalves better adapted to changing conditions. Left, Devonian brachiopod fossils from Ohio, USA. Right, recent bivalve shells from Shell Beach, Western Australia. Credit: (Wikimedia Commons; Creative Commons CC0 1.0 Universal Public Domain Dedication) for image on the left. Image on right by Zhong-Qiang Chen.
SciTechDaily has a piece about the rise of the mollusks over the brachiopods after the Permian Mass Extinction. Scientists have long wondered why bivalve species like clams and oysters replaced the brachiopods about 250 million years ago. During the Paleozoic, brachiopods dominated the sea floor, but they are now just a small part of the ecosystem. What happened? New research conducted by paleontologists in Bristol, UK and Wuhan, China used Bayesian analysis to understand why. The details can be found in a new paper in the journal Nature Communications.
“We wanted to explore the interactions between brachiopods and bivalves through their long history and especially around the Permian-Triassic handover period,” said Joe Flannery-Sutherland, a collaborator. “So we decided to use a computational method called Bayesian analysis to calculate rates of origination, extinction, and fossil preservation, as well as testing whether the brachiopods and bivalves interacted with each other. For example, did the rise of bivalves cause the decline of brachiopods?”
“We found that in fact, both groups shared similar trends in diversification dynamics right through the crisis time,” said Professor Michael Benton from Bristol’s School of Earth Sciences. “This means that they weren’t really competing or preying on each other, but more probably both responding to similar external drivers such as sea temperature and short-lived crises. But the bivalves eventually prevailed and the brachiopods retreated to deeper waters, where they still occur, but in reduced numbers.”
