450-Million-Year-Old Crinoid Fossil Preserves Rare Soft Tissue
Paleontologists at the University of Oklahoma have identified a 450-million-year-old fossil that preserves soft tissue from an ancient crinoid, a marine animal related to modern starfish.
The specimen belongs to Dendrocrinus simcoensis, an extinct species of crinoid. Its preserved tube feet represent only the second known example of fossilized soft tissue in crinoids and the oldest such discovery ever documented.
"After an animal dies, soft tissues like skin, eyes, or internal organs are the first things to decay," said Dr. Lena Cole, OU paleontologist and assistant curator of invertebrate paleontology at the Sam Noble Oklahoma Museum of Natural History. "Most fossils are only made up of hard parts like bones, teeth, or shells. Soft tissues are only preserved when the environment acts almost like a natural refrigerator or vacuum‑sealer -- conditions that are incredibly rare."
"Preservation like this is truly one in a million," Cole added. "Crinoid fossils number in the millions, and this is only the second time soft tissues have ever been found."
Dr. David Wright, another OU paleontologist and assistant curator of invertebrate paleontology at the Sam Noble Oklahoma Museum of Natural History, co-authored the study with Cole. "It's incredible these soft tissues have survived more than 450 million years," Wright said. "For reference, these soft tissues are more than 200 million years older than the oldest dinosaur."
The fossil's preserved tube feet provide clues about how crinoids obtained food and interacted with their surroundings. Crinoids rely on specialized structures to capture food particles from seawater, and their tube feet play an important role in feeding and in how these animals interact with ocean currents.
"Since crinoid tube feet are used for feeding, you can think of them in a similar way to how we think about teeth in mammals," Wright explained. "Differences in their structure tell us about what kinds of environments a species lived in and how it fed."
Researchers compared the ancient fossil with crinoids living in today's oceans. Those comparisons revealed notable anatomical differences, suggesting that the feeding structures of these animals have undergone substantial evolutionary changes over hundreds of millions of years.
"Comparisons with living crinoids show that the anatomy of this ancient species was very different," Cole added. "This gives us new insight into how crinoids evolved and how their feeding strategies changed over hundreds of millions of years."
The fossil had been housed for years at Montréal's Musée de paléontologie et de l'évolution, a small museum that operates entirely with support from community donations. Its scientific value became apparent when Cole and Wright visited the museum and examined the specimen more closely.
"This discovery highlights the importance of museum collections and the community support that keeps them alive," Cole said. "Without the dedication of many people caring for these collections, this research would never have been possible."
At the Sam Noble Oklahoma Museum of Natural History, Cole and Wright oversee invertebrate paleontology collections containing more than one million specimens.
"This is why we work to make our collections accessible to researchers around the world," Wright said. "There are simply too many fossils to study over one person's career. There's more than a lifetime's worth of discoveries waiting to be found."