Dinosaurs: a Museum guide
At the rear of the upper gallery are some good original specimens of dinosaurs, displayed with replicas of other material.
The British Isles produced the first dinosaur remains ever to be identified, and has also yielded some quality material in recent years, especially from the Isle of Wight. Most of the spectacular dinosaur material is uncovered in the United States and China, and museums can only display replicas of this. This exhibit has been arranged to highlight the diversity of material in our collections, and to demonstrate families of dinosaurs represented there.
Dinosaurs fall into two main groups, the lizard-hipped forms – saurischians – and the bird hipped forms – ornithischians – which are further divided as:
|sauropods||mainly herbivorous||four legs|
Replicas of several theropod skulls are displayed, the largest being that of the Allosaurus, a relative of the tyrannosaur. The Allosaur was much smaller than a Tyrannosaurus Rex, though just as viscious, and they lived earlier in time. The skull of Velociraptor can also be seen – note that it is much smaller than suggested in the film, ‘Jurassic Park’. This animal was probably not much bigger than a large dog such as an alsatian. Coelophysis, also represented in the display by a replica skull, was one of the earliest and most primitive of therapods, and was found in the Triassic rocks of the western United States.
Sauropods, with their long necks and tails, are represented by one of their elongate eggs. The genuine egg in the display is from China. Sometimes, unbroken dinosaur eggs can be dissected to show the embryo inside, allowing scientists to obtain information about what kind of dinosaur laid the eggs and something about how they grew.
The prosauropods, such as Plateosaurus, were smaller, two-legged relatives of the sauropods. Their lifestyle is not clearly known. They may have been partly carnivorous. In the display, we have replicas of a prosauropod skull and one of the hind feet.
All dinosaurs in this family were herbivorous and had skulls and teeth adapted for dealing with plant material. One of the earliest ornithiscians was Hypsilophodon, whose skeleton was found on the Isle of Wight. This replica skeleton shows its two-legged posture, where the tail balances its forequarters. A partial pelvic girdle of Iguanodon, also from the Isle of Wight and a later relative, gives an idea of how much larger it was than Hypsilophodon. The skull of Heterodontosaurus shows how this particular dinosaur got its name – the teeth (‘dont’) are of different (‘hetero’) shapes, some for crushing and some for piercing. It is not clear whether this animal was entirely herbivorous or not.
The only representative specimen of the ceratopians in this exhibit is a replica of the brain cavity from a specimen of Triceratops. You can see where the different components of the brain were lodged, and where some of the main cranial nerves came out of it.
Other dinosaur specimens
At the bottom of the case in front of the skeleton of Hypsilophodon is a dinosaur footprint found on the coast of Dorset. The rock layers where it came from, known as the Purbeck Beds, extend quite widely around Swanage, and have yielded many kinds of dinosaur tracks. This one is from the foot of a three-toed dinosaur, possibly a medium-sized theropod, though it is impossible to say for certain.
A section through a piece of dinosaur leg bone has been polished to show its structure. You can see the outer layer of laminated bone and the inner, more spongy bone. By studying such material under the microscope it has been possible to show that many dinosaurs, especially theropods, grew very quickly when they were young. This information has been used to suggest that they were warm-blooded like birds, and certainly they seem to have had high metabolic rates to produce rapid growth. It seems that theropod dinosaurs and birds are each other’s closest relatives, so similarities between the two in growth and metabolism are likely.