• Serpentes;
  • snakes;
  • aggregation;
  • palaeoethology;
  • Ogmophis;
  • Calamagras;
  • Oligocene;
  • White River Formation;
  • Wyoming

Three virtually complete skeletons in east-central Wyoming of the Oligocene erycinine boid snakes Ogmophis and Calamagras represent the oldest known record of serpent aggregation. The skeletons are articulated and coiled loosely together in life-like positions in a horizontal plane within sediments of the White River Formation. The fossils represent an autochthonous, fluvial burial of snakes some 32 million years ago. Taphonomic considerations suggest the preservation of an aggregative event that occurred just prior to death. We suggest that serpent aggregation is a conservative, relatively unchanged form of behaviour, with a minimum age of 32 million years before present.