Fossilised copulating turtles

Palaeontologists are at a loss to come up with the mechanism of death in fossilised copulating turtles. The paired turtles had been known for some time and, while mating had been hypothesised, the confirmation that each of the pairs were male and female, as well as some specific positioning, has strengthened the theory.

Male turtles of this species, like many of their modern relatives, have longer tails than females, said Joyce. Also, males were typically smaller than females, a trend clearly seen in the fossils. Finally, in seven of the nine pairs, the turtles are in direct contact along the edge of their shells just above their tails - and in two of those pairs, the male's tail wraps below the female's shell in mating position.

What mechanism would cause the death of 9 (!) pairs during mating? Toxic algal blooms; carbon dioxide in the water; other toxic substances. The proposal is oxygenated upper lake water and saturation of the lower lake water with carbon dioxide or other toxins. They claim this causes death during the act followed by preservation in the oxygen poor water. This seems a bit of a stretch, and so many pairs. It would be interesting to know if turtles stop mating during forced suffocation.

I prefer the creationist proposal for fossilisation: burial in sediments such as mud and lava flows during flooding and volcanic activity. Rapid death and conditions for fossil formation occur together. This explains the mechanism of fossilisation which does not usually occur when animals die; fossil graveyards; and why animals are found in situations such as eating, or giving birth.