Aviculopecten lautus variety ithacensis Kindle, 1896
Family Pectinidae (True Scallops)
Who knew that Ithaca, the site of the Paleontological Research Institution, has its own species of scallop! This is PRI 28298, Aviculopecten lautus variety ithacensis, described in the second volume of Bulletins of American Paleontology by Edward Kindle in 1896. It is from the Middle Devonian Period, about 375 million years ago, collected from the foot of Ithaca Falls. It is only 13 millimeters wide (about one-half inch) and has fine radially ribbed sculpture, as seen in the fossil and also in the drawing that accompanied the original description. This is a holotype specimen, one of the most valuable parts of PRI’s collection.
The Species: Scallops are very interesting animals. They are unusual bivalves in that they do not burrow beneath the sand like a typical clam. They rest on top of the sand, and can swim by clapping their two valves together using the strong, single adductor muscle (this is the part that you eat as “scallops”). Their swimming method is a kind of jet propulsion — when the shells snap shut, water jets out the tiny “ears” at the back of the shell. Scallops also have dozens of tiny eyes along the rim of their shells — these don’t form images, but can detect shadows and thus an approaching predator. Then it’s time to swim away!
Evolution on the Half Shell...
The Assembling the Tree of Life: Bivalvia project (BivAToL) is a part of the Assembling the Tree of Life initiative, a large research effort sponsored by the National Science Foundation. Its goal is to reconstruct the evolutionary origins of all living things.
Jetsam & Flotsam
Some of the BivATOL team met in early May at the Mote Marine Laboratory’s Tropical Research Station at Summerland Key, FL for a combined collecting trip and coding workshop. Both activities are essential to our project’s goal of determining the phylogenetic relationships among the bivalve families.
After collection, many of the species’ visible and molecular characteristics must be compared and “coded,” after which the phylogenetic computer analyses will be run to produce the final “tree” from which a hypothesis of relationships can be made. Below is an example of a portion of such a phylogenetic tree. Families that are on nearby branches are more closely related to each other than those further away.