The research objective is the development and use of an accurate predictor of limb sophistication in fossil reptiles using gross spinal anatomy. Such a tool will allow augmentation of functional inferences based on limb osteology alone and allow predictions of limb use when appendicular data is inadequate or absent. A method of quantifying and standardizing variations in segmental spinal cord area in living reptiles and birds has been accomplished with a spinal index. Predictions of cord size based on neural canal size are presently based on size relationships in subadult Alligator specimens. Improved ability to predict cord size in extinct reptiles will be accomplished by dissection and measurement of both cord and canal in additional ontogenetic stages and taxa. Preliminary correlation of size of spinal index and sophistication of limb use suggests that the index may be a sensitive indicator of limb function. Measurement of a much larger number of taxa displaying a greater spectrum of limb adaptations will allow finer calibration of the spinal index. Application of data from living genera to the fossil record will be obtained from museum collections. Although applications of the technique are wide and varied, only three specific questions of limb function in fossil reptiles are covered by this proposal. These involve forelimb use in theropods, role of torso and limb as propulsive organs in aquatic tetrapods, and hindlimb/tail use in armored dinosaurs.
