Minmi paravertebra– an armoured dinosaur
(Queensland Museum Image)
An almost complete fossil of a small plant eating dinosaur - an ankylosaur - was discovered near Richmond in 1989. A local grazier spotted it while mustering cattle on his family property. It is Australia's best preserved dinosaur skeleton and one of the most important of its kind in the world. Most of the bones were found articulated - still joined together. This individual was found lying on its back.
Minmi lived about 100 million years ago. We know this because the rock formation that the fossil was preserved in has been placed in the chronological sequence with other older and younger formations. These have been dated by measuring the amount of certain radioactive elements contained within the rocks.
(Minmi skeleton reconstruction by Paul Stumkat)
At the time an inland sea flooded the low lying areas of what is now central and eastern Queensland. The climate was wetter than at present. Land bordering the sea was able to support forests. Tree trunks as well as dead animals were occasionally washed into the sea where they sometimes become preserved as fossils. This is what happened to Minmi.
Minmi probably did not die at sea. The carcass may have been carried from the land, perhaps by a river in flood. As the bones were preserved relatively complete and articulated, burial in the mud of the sea bed must have been fairly rapid. This had to occur before the bones and soft tissues could disintegrate or be scattered by the current or by scavengers.
Several partial skeletons of ankylosaurs have been found in other parts of the world during the last 70 years. Scientists studying them have been able to build up a picture - although incomplete - of what they might have looked like and how they might have behaved.
(Minmi head reconstruction by Paul Stumkat)
Even though many of the bones of Minmi are still embedded in rock, we can assemble the skelton on paper and put flesh on the bones to give a impression of the animal's appearance in life. Some large ankylosaurs from North America had a large bony tail club. The tail of Minmi was not preserved so we do not know if it had a club. Ossified tendons ran along the tail making it stiff and inflexible.
The ossicles and scutes imbedded in the skin of the living animal formed the armour charactistics of ankylosaurs. In the Richmond specimen they have been preserved in place.
