June 12, 2025
Contact: Eric Stann, StannE@missouri.edu
Photos courtesy Sarah Jacquet

More than 514 million years ago, long before dinosaurs roamed the Earth, sponge-like creatures called archaeocyathids were already busy building some of the planet’s earliest reefs — just north of Death Valley in present-day Nevada.

In a recent study, University of Missouri researchers looked at how these ancient reef-building organisms shaped their environment. They also studied tiny, fossilized sea creatures called “small shelly fauna” — some of the earliest animals with hard shells ever found on Earth.

Modern coral reefs are known as biodiversity hotspots, teeming with marine life and supporting entire ecosystems. But this study found that early reefs did not appear to boost biodiversity in the same way, Casey Bennett, a graduate student in the Department of Geological Sciences and lead author on the study, said.

“With modern reefs, biodiversity is expected to decrease as you move away from the reef structure due to reduced shelter and food access,” she said. “However, we didn’t find a consistent pattern with these ancient reefs — instead, it was pretty inconsistent and was largely dependent on localized conditions.”

This discovery offers a glimpse into how life evolved in early oceans and challenges assumptions about how ecosystems develop around reef structures. It’s a reminder that not all reefs are created equal, and understanding their ancient forms could offer insight into how modern marine systems might change.