(I) In a rare instance of a vertebrate's behaviour being revealed by its fossil, a new species of dinosaur was found with its head tucked under a forelimb. (II) It represents the earliest known example of a dinosaur displaying the sleeping posture exhibited by modern-day birds. (III) As a result, though it is not known how the dinosaur died, it probably was killed instantly by a thick deposit of volcanic ash or by volcanic gas followed by a covering of ash and mud. (IV) The “tuck-in” pose would have preserved body heat, suggesting that, like birds, at least some dinosaurs were warmblooded. (V) Delighted palaeontologists named this pigeon-sized dinosaur “Mei long”, meaning “soundly sleeping dragon.”