More than 450 million years ago, long before dinosaurs appeared and before animals or plants had spread widely across dry land, crinoids were already thriving in some of Earth's earliest coral reefs. These ancient relatives of starfish looked somewhat like flowers growing on stalks beneath the sea. Crinoid fossils give paleontologists important clues about how early animals evolved and how complex life developed.
But fossils usually preserve only durable structures such as shells or skeletal plates. Delicate tissues tend to disappear quickly after death, leaving major gaps in scientists' understanding of how these animals actually lived. A remarkably rare fossil studied by University of Oklahoma paleontologists is now helping fill in part of that missing picture.
"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." The fossil belongs to Dendrocrinus simcoensis and preserves its tube feet, delicate structures that almost never survive fossilization. Cole and her colleagues describe the specimen in a new study. Only two known crinoid fossils have ever been found with preserved soft tissue.
This specimen is also the oldest example discovered so far. "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." The preserved tissues date back more than 450 million years, making them far older than the earliest dinosaurs.
"It's incredible these soft tissues have survived more than 450 million years," said Dr. David Wright, another OU paleontologist and assistant curator of invertebrate paleontology at the Sam Noble Oklahoma Museum of Natural History, who co-authored the study with Cole. "For reference, these soft tissues are more than 200 million years older than the oldest dinosaur." For crinoids, tube feet play an important role in feeding, responding to water currents and occupying different ecological niches.
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