More than 450 million years ago, long before dinosaurs dominated the Earth and when plants and animals were just beginning to spread on land, crinoids were already thriving in some of the planet's earliest coral reefs. These ancient relatives of starfish resembled flowers growing on stalks on the ocean floor.
Crinoid fossils often provide valuable clues about the evolution of early animals and the development of complex life. However, in most cases, only hard structures, such as skeletal plates or shells, are preserved. Delicate tissues quickly disappear after the organism's death, leaving significant gaps in scientific knowledge about how these animals actually lived.
An exceptionally rare fossil, studied by paleontologists at the University of Oklahoma, is helping to fill in part of that incomplete picture. “After an animal dies, soft tissues like skin, eyes, or internal organs are the first to decompose,” explained Dr. Lena Cole, a paleontologist at OU and assistant curator of invertebrate paleontology at the Sam Noble Oklahoma Museum of Natural History.
“Most fossils are 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 a vacuum seal: conditions that are incredibly rare,” she added.
The specimen belongs to the species Dendrocrinus simcoensis and retains its tubular feet, delicate structures that almost never survive fossilization. Cole and her colleagues describe the specimen in a new study. Only two crinoid fossils with preserved soft tissue are known, and this is the oldest discovered so far.
The oldest known crinoid soft tissue
“A preservation like this is truly one in a million,” Cole added. “Crinoid fossils are counted in the millions, and this is only the second time soft tissues have been found.” The preserved tissues date back over 450 million years, making them much older than the first dinosaurs. “It’s incredible that these soft tissues have survived for more than 450 million years,” noted Dr. David Wright, another OU paleontologist and co-author of the study. “For reference, these soft tissues are over 200 million years older than the oldest dinosaur.”
In crinoids, tubular feet play a central role in feeding, responding to water currents, and occupying different ecological niches. Their size, spacing, and overall shape can vary depending on the environment and the animal's feeding method. In that sense, they reveal information about lifestyle in a similar way to how mammal teeth inform about diet.
“Since the tubular feet of crinoids are used for feeding, they can be thought of similarly to how we think about teeth in mammals,” explained Wright. “Differences in their structure tell us about what types of environments a species inhabited and how it fed.” By comparing the fossil with current crinoids, researchers found notable differences in anatomy.
“Comparisons with living crinoids show that the anatomy of this ancient species was very different,” Cole added. “This gives us a new insight into how crinoids evolved and how their feeding strategies changed over hundreds of millions of years.”
The finding not only expands knowledge of crinoid anatomy. It also helps reconstruct the ecology of early Paleozoic oceans, when these organisms were among the many groups of early animals thriving in reef ecosystems.
New clues about ancient oceans
“Fossilized remains of long-extinct species can show traits far outside the range of variation we see in living species,” Wright indicated. “By comparing the ecological life forms of extinct and modern species, we can understand how patterns of adaptive evolution changed over time and what factors shaped the current biosphere.”
Soft tissue is exceptionally rare in early echinoderm fossils, the broader group that includes crinoids and starfish. Since so little of it survives, each new specimen discovered can significantly increase what researchers know about ancient ecosystems, feeding behavior, and evolutionary change.
Many people imagine that great paleontological discoveries occur during expeditions in remote landscapes. While fieldwork produces new fossils, important findings can also arise from specimens that have been stored, cataloged, and protected in museums for years. The Dendrocrinus simcoensis fossil with preserved soft tissue had remained for years at the Musée de paléontologie et de l’évolution de Montreal, a small museum that operates entirely on community donations. Its unusual scientific importance became evident when crinoid specialists Cole and Wright examined it closely during a research visit.
“This discovery highlights the importance of museum collections and the community support that keeps them alive,” Cole stated. “Without the dedication of many people who care for these collections, this research would never have been possible.” The invertebrate paleontology collections managed by Cole and Wright at the Oklahoma Museum of Natural History contain over a million specimens, and additional fossils are added each year. Collections of that scale can harbor discoveries that go unrecognized until years or even decades after the specimens were first collected.
