VMNH Dig Reveals Marine Fossils
Sunday, August 21, 2011
By ASHLEY JACKSON - Bulletin Staff Writer
Several intriguing marine fossils were uncovered during the Virginia Museum of Natural History's recent excavation, a museum official said.
During the excavation at the Carmel Church quarry near Richmond, a new pit was opened where fossils from marine wildlife such as whales, sharks, fish, seaturtles and marine crocodiles that date back 14 million years were extracted, according to Alton Dooley Jr., assistant curator of paleontology.
The group of about eight volunteers - college students and enthusiasts who paid to take part - joined Dooley in the excavation. The dig lasted from July 18-29 with each day consisting of about 10 hours of digging in hot weather, Dooley said.
One day during the trip, the thermometer in his truck, which was parked in the shade with the windows down, read 112 degrees, Dooley said.
To beat the heat, everyone would begin digging earlier in the morning, but it still was hot even at that time, Dooley said. "The heat made it tougher on us" to dig, he said.
The most intriguing findings at the quarry were three different lower jaw bones and a tiny fragment of a skull from "baleen," or great whales, and several dolphin bones, including a dolphin neck vertebrae and ear bone.
The quarry at Carmel Church is a rich site to excavate, according to Dooley. He said 17 different species of whales and dolphins have been identified at the site.
"I'm intrigued by these dolphin ear bones" because he does not know what kind of dolphin they are from, Dooley said.
Also intriguing was an upper arm bone from a sea turtle which was "the first complete specimen that we've found" there from a seaturtle, Dooley said. In the past, only shell fragments had been found at Carmel Church, he added.
This excavation was one of the about four that the museum participates in each year. The purpose of each excavation is to extract specimens and fossils to be used in exhibits at the Martinsville museum but also for marine wildlife studies.
Currently at the museum, there are two studies being conducted using marine fossils that the museum has in its collection, Dooley said.
One study is using the museum's 600 specimens of shark teeth to look at the way teeth break in different sharks in order to find out what each shark ate in its habitat.
The other study is looking at different whale specimens to find patterns in the preservation of certain parts of the whale. "With data like that, we see the environment in which they (the whales) lived in," Dooley said.
The Carmel Church findings also will be used in research to "try to understand how all of these fossils" ended up in such a small space, Dooley said. They have found thousands of fossils in an area that is only a few 100 yards long, he added.
The excavation process is not an easy one. To even reach the bonebed, excavators use picks and shovels to remove 20 years of sediment that has washed down over the surface. The sediment includes iron, sulfur and carbonate minerals, according to Dooley.
Once they reach the bone level, they dig a trench and cover the surface with plaster. Once that hardens, the block of plaster is flipped over to scoop up the fossils safely.
The fossils remain in the plaster to be transported back to the museum. There, the plaster is removed and the bones are cleaned under controlled conditions, he said.
Dooley and other excavators will return to the Carmel Church quarry in the fall to continue digging up fossils from the new pit that they opened. Martin Marietta Materials Inc. operates the quarry and allows the museum to excavate at the private site.
Each day's activities and findings during the trip were documented in Dooley's blog at www.paleolab.org.