Size Estimates of Extinct Eocene Aquatic Snakes from Central Georgia
Abstract
Eocene aged sediments of the Barnwell Group outcrop across central Georgia just south of the modern fall line. The Barnwell Group is described as a fossiliferous, quartz sand dominated unit with terrestrial and coastal facies. The coastal facies represents near-shore marine environments and contains occasional limestone beds. Across portions of central Georgia, extensive deposits of kaolin lie immediately beneath the sediments of the Barnwell Group, and mining operations to recover kaolin often expose these fossil bearing sediments. Here we describe Eocene snake fossils recovered from an active kaolin mine in Wilkinson County, Georgia. The material was recovered by surface collecting fossiliferous horizons exposed by mining operations. In addition to fossil snakes, fossils of many sharks, sawfish and rays, turtles, and some larger marine mammals were recovered. A comparison of the Wilkinson County mine fossils with the nearby Hardie Mine fauna suggests comparable ages. The Hardie Mine deposits come from the Riggins Mill Member of the Clinchfield Formation which date to the Late Eocene, 34.5-35.5 ma. Two genera of aquatic marine snakes (Palaeophis and Pterosphenus) are known to occur in Eocene marine sediments in Georgia. In an attempt to estimate the length of these ancient sea snakes, centrum length measurements were taken on the vertebrae of modern boids (Boa constrictor and Liasis boeleni) of known lengths using digital calipers. A regression analysis was performed on the measurements, and we found a strong relationship between centrum length and total body length. The regression equation was used to estimate the total body lengths of the fossil snakes based on the same centrum measurements. The estimated total body length of the ancient sea snakes ranged between 1.6 and 5.3 meters. Although not directly related to the modern sea snake, the ancient ones were up to 4 meters longer than the modern counterparts.
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Size Estimates of Extinct Eocene Aquatic Snakes from Central Georgia
Eocene aged sediments of the Barnwell Group outcrop across central Georgia just south of the modern fall line. The Barnwell Group is described as a fossiliferous, quartz sand dominated unit with terrestrial and coastal facies. The coastal facies represents near-shore marine environments and contains occasional limestone beds. Across portions of central Georgia, extensive deposits of kaolin lie immediately beneath the sediments of the Barnwell Group, and mining operations to recover kaolin often expose these fossil bearing sediments. Here we describe Eocene snake fossils recovered from an active kaolin mine in Wilkinson County, Georgia. The material was recovered by surface collecting fossiliferous horizons exposed by mining operations. In addition to fossil snakes, fossils of many sharks, sawfish and rays, turtles, and some larger marine mammals were recovered. A comparison of the Wilkinson County mine fossils with the nearby Hardie Mine fauna suggests comparable ages. The Hardie Mine deposits come from the Riggins Mill Member of the Clinchfield Formation which date to the Late Eocene, 34.5-35.5 ma. Two genera of aquatic marine snakes (Palaeophis and Pterosphenus) are known to occur in Eocene marine sediments in Georgia. In an attempt to estimate the length of these ancient sea snakes, centrum length measurements were taken on the vertebrae of modern boids (Boa constrictor and Liasis boeleni) of known lengths using digital calipers. A regression analysis was performed on the measurements, and we found a strong relationship between centrum length and total body length. The regression equation was used to estimate the total body lengths of the fossil snakes based on the same centrum measurements. The estimated total body length of the ancient sea snakes ranged between 1.6 and 5.3 meters. Although not directly related to the modern sea snake, the ancient ones were up to 4 meters longer than the modern counterparts.