Paper No. 16-11
Presentation Time: 10:45 AM-11:00 AM
SIZE-FREQUENCY DISTRIBUTION OF LEOPARD FROGS (RANA PIPIENS COMPLEX) FROM THE LATE TERTIARY PIPE CREEK SINKHOLE, GRANT COUNTY, INDIANA
SHEETS, Hope A. and FARLOW, James O., Department of Geosciences, Indiana-Purdue Univ, Fort Wayne, IN 46805, hasheets@msn.com

The Pipe Creek Sinkhole (PCS) preserves a continental vertebrate fauna of late Tertiary (latest Hemphillian Land Mammal Age, c. 5 million years BP) age. The fauna is dominated by aquatic species, particularly leopard frogs. Unconsolidated sediments from the deposit were wet-sieved, yielding a large collection of leopard frog ilia (hip bones--the most diagnostic skeletal element for frogs). We digitally scanned 202 left ilia from the fossil assemblage, as well as ilia from modern leopard frogs of known size (snout-vent length [SVL]). From the digitized images we measured the vertical diameter (AD) across the acetabulum (hip socket). AD is positively correlated with SVL, indicating that AD is a suitable proxy for frog size. The size-frequency distribution of AD for the PCS leopard frogs suggests three possible modes. If the PCS leopard frogs represent a single species, these modes probably reflect a mixture of age classes and sexual dimorphism (females larger than males). The effects of sex and age might be disentangled by a skeletochronological study of the PCS frog ilia.

North-Central Section - 37th Annual Meeting (March 2425, 2003)
General Information for this Meeting
Session No. 16
Paleontology and Paleobotany
Kansas City Airport Hilton: Kansa E
8:00 AM-12:00 PM, Tuesday, March 25, 2003
 

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