Page 459 - The Secret Museum

information about feeding in a huge animal that has to eat a lot. Not having the skull is

a big missing piece.’

Except it’s not that big. It’s really rather small, for the head of a vast dinosaur.
The volume of the head is about one two-hundredth of that of the whole animal.
Imagine if our heads were on that same scale to our bodies. How strange we would
look with heads the size of tennis balls.

The skull still has a fair bit of rock on it, which is gradually being removed in the
lab at the museum with a microscope and a tiny pneumatic drill. But what do we
know so far about this individual dinosaur? Well, we know that 120 million years
ago it was walking around in what is now Brazil. On the basis of skeletal anatomy, it

seems to be a young adult, a teenager: it still has soft spots in its skull, and the joints
between its backbones are really obvious. Vertebrae fuse when a creature becomes
an adult. So we know that this dinosaur would have grown bigger if it lived for
longer.

It had 64 teeth – 32 on each jaw. The teeth are thin and look as if they’d break
easily. Their size can be explained by the necessity to pack them all into the
dinosaur’s small jaw. There are several generations of teeth inside this dinosaur
mouth, waiting inside the gums, and this set of teeth is unlikely to be the dinosaur’s

first. Mammals are unusual in that they only have two sets of teeth – like sharks,
dinosaurs continually replace their teeth. Sauropods, this teenager included, got a
new set of pencil-like gnashers every few months.

We don’t know what sex it was. With some species of dinosaur the sex can be
determined from the remains, but not with sauropods. Maybe sex was evident in other
ways – colours, ornamentation – it’s not yet clear.

When it was born, it was alone. Some species of dinosaur – like some birds, the
descendants of dinosaurs that are still living – laid eggs and left them; others cared
for their young. Jeff explained, ‘We’ve found huge nesting areas with lots of eggs and
no adults. We have even found snakes inside dinosaur nests, waiting, ready to eat the

emerging hatchlings.’ When this dinosaur hatched, it was half a metre long and
fended for itself immediately. Then it managed to survive into its teens, before dying
and resting in what became Brazil for millions of years until, one day, it became a
national treasure.

It is an especially precious fossil because it allows scientists to make new
discoveries about dinosaur evolution. When dinosaurs first lived on Earth, in the
Triassic period, all the continents were gathered into one landmass, so we see
genealogical continuity among the dinosaurs. Meat-eaters from South Africa look like

meat-eaters from Arizona. Across a couple of generations, a dinosaur species could
populate the whole Earth and so preserve its genetic continuity.

But then, over these millions of years, the continents began to break up. Whereas
before, the sauropods roamed across one large landmass, as the continents moved