Cincinnati -- It isn't the lifestyles of the rich and famous that University of Cincinnati geologist David Meyer is concerned about, but Meyer's efforts to understand the lifestyles of the ten-armed fossil crinoid Uintacrinus did send him globe-trotting this year. His work took him to several locations in Germany, to the badlands of Kansas, and to the sagebrush country of Colorado.
One of his collaborators, Clare Milsom of Liverpool John Moores University will present the latest findings from their field work at the British Paleontological Association meeting in Portsmouth, England, Thursday, Dec. 17.
Meyer and Milsom are searching for evidence that will support or refute the hypothesis that Uintacrinus could float a rather staggering feat considering its size and the fact that there simply never has been a crinoid known that could float. Crinoids are invertebrates related to sea stars and sea urchins.
"You've got a very strange case here," said Meyer. "They're basically a plated, shelly creature that's heavier than water. It has no known flotation devices, so the burden of proof is on someone who says they did float."
Alternately, some have argued that Uintacrinus stayed afloat by treading water with its long, spaghetti-like arms. Meyer can't accept that explanation. "In truth, the crinoid animal doesn't have the energy resources to keep treading water indefinitely. I've studied them. My knowledge of living crinoids has been very helpful here. Living crinoids that are able to swim don't swim constantly. They only do it in short bursts."
Uintacrinus lived in dense mats in the shallow seas during the Cretaceous about 85 million years ago. Classic fossil finds include several table-sized slabs with hundreds of organisms intertwined in an odd spoke-like pattern. Typically, marine fossils are preserved lined up in parallel rows when a storm or currents smother them in sediment. The spoke-like pattern is unique to Uintacrinus and a real puzzle to Meyer.
"It's like you take a bunch of 'Pick-Up Sticks.' You let them fall from a group and they fall out in a pattern. You see these round crinoid bodies with their arms lying in toward the center."
The pattern has been recognized for over 100 years, because Uintacrinus was one of the "trophy" fossils heavily prized by collectors. The best slabs were collected in North America, but many were sent overseas to Europe which prompted Meyer's trip to Germany. There, he visited several museums and field sites to get detailed records of the exact alignment of the Uintacrinus fossils. The spoke pattern was evident on some, but not all of the slabs.
Meyer then returned to the United States in search of new fossil evidence in Kansas and Colorado. Unfortunately, the early trophy hunters left few clues as to where there treasures were found, and the fossils were collected for their beauty with little regard to the scientific information they could also provide.
"The real advance has been going back to the field areas and finding new material in the field which has not been done for decades by any scientific effort," said Meyer. Working with UC graduate student Andrew Webber and Milsom, the researcher found samples from both Kansas and Colorado. "We've obtained material 'in place' that demonstrates where the fossils are found in the rock and their relationship to the rock in which they're buried which is going to help us understand how they were preserved and hopefully answer how this very strange crinoid lived."
In addition to the field work, Meyer hopes to develop a physical or computer model of Uintacrinus to test different theories on how it might have survived and been preserved. In the floating model, the extended arms might have provided enough surface tension to keep the large mats on the surface of the shallow oceans. Then, the arms might have twisted together in a clump as storms or other natural disasters sent the mats plunging toward the sea floor.
Meanwhile, Webber is using a geochemical approach to determine whether the crinoid sat on the sea floor with its arms extended upward to catch food or floated instead. Webber is looking at different isotope ratios for carbon and oxygen which can indicate whether an organism was a bottom-dweller or not.
The project is supported by the National Geographic Society.
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