Non-avian dinosaur and bird fossils are frequently found in a characteristic posture consisting of head thrown back, tail extended, and mouth wide open.
Traditional explanations ranged from strong ligaments in the animal's neck desiccating and contracting to draw the body into the pose,[1] to water currents arranging the remains in the position.
[2] Faux and Padian suggested in 2007 that the live animal was suffering opisthotonus during its death throes, and that the pose is not the result of any post-mortem process at all.
A study conducted by Alicia Cutler, Brooks B. Britt, and colleagues from Brigham Young University suggests that the pose is a result of submersion in water after death.
According to the conclusions of this study, the so-called "opisthotonic posture" is not the result of a cerebral illness creating muscle spasms, and also not of a rapid burial.