Taphonomy of Freshwater Turtles: Decay and Disarticulation in Controlled Experiments

We conducted an experimental study of the timing and nature of taphonomic processes in turtles that allowed a comparison among different environments. We documented decay and disarticulation of freshly-killed aquatic turtles in controlled settings, including freshwater and seawater aquaria, and outdoor terrestrial settings protected from scavengers. The study area was in hot and dry southern California, with scattered winter rains. We transferred some specimens after 53 days from the terrestrial environment to one of two other environments freshwater, or an outdoor terrestrial cage simulating increased rainfall. In water, turtle flesh decayed by bacterial action in three and a half to five months, but insect larvae removed the flesh from terrestrial carcasses within two weeks, leaving dry, desiccated carcasses. Turtles disarticulated most rapidly in water, followed by the high rainfall treatment, then dry terrestrial. The sequence of disarticulation of different bones from the body varied considerably, especially in the terrestrial treatment, but there were some consistent trends. Heads and necks, tails, and limbs tended to disarticulate early in the process. Next the carapace, and lastly, the plastron, disarticulated. Minor weathering occurred on the inside surface of some shell bones in the terrestrial environment. These data provide a basis for estimating maximum length of exposure of fossil turtles before burial and for comparison of turtle taphonomy with taphonomy of other small vertebrates.