Marine biologists study the arrangement of ancient fish fossils to deduce the conditions under which these fish lived. A significant number of fish fossils are found in a curled position known as coiling, which researchers indicate is often seen in fish that experienced extreme stress or rapid changes in their environment. This leads to the conclusion that many of the fish whose fossils are found in coiling died due to environmental shocks, possibly from volcanic eruptions or drastic temperature changes.

Which of the following, if true, most weakens the reasoning above?