How It Works-Book Of Dinosaurs

Quetzalcoatlus

Although not technically regarded as ‘dinosaurs’, pterosaurs were around at a

similar time and are often (somewhat incorrectly) referred to as ‘fl ying dinosaurs’,

much to the ire of some palaeontologists. Nevertheless they were impressive

creatures, and none more so than Quetzalcoatlus, the largest fl ying animal of all

time. Its huge 2.5m (8ft) skull housed an elongated mouth that was used to hunt land

animals including dinosaurs and other vertebrates. Despite its size Quetzalcoatlus

was comparatively light as its bones were comprised of a series of air sacs, a usef ul

feature for such a colossal creature aiming to take to the skies. While most other

pterosaurs fed on fi sh, Quetzalcoatlus was somewhat unique in its hunting of land

animals, no doubt usef ul nutrition to f uel its giant metabolic needs.

How It Works: Can you describe

your current role within the world

of palaeontology?

Mike Benton: I work in a 50:50

teaching and research position – I

teach undergraduates, both

geologists and keen palaeontologists,

and especially I teach Masters and

PhD students. Every year, some

20-25 new Masters students and

four-fi ve new PhD students come

from all parts of the world to work

with us, and I really enjoy working

with them to help them develop their

careers. In research, I work on several

topics by myself, on others with my

students, and on others with

collaborators around the world.

Could you briefl y summarise the

key methods

and techniques used in

the identifi cation of

prehistoric creatures?

Palaeontologists identify fossils

based on the existing knowledge of

living and extinct forms. The fossils

are often incomplete, and usually

show only the hard parts, such as

shells and bones. But, if there is a

living relative, these parts can be

identifi ed, and a fair attempt made to

identify what the fossil is. Usually,

palaeontologists have many fossils of

the same animal or plant to work

with, and they can compare these.

Can you describe some of the

challenges involved in identifying

a dinosaur?

Dinosaurs are all extinct, and their

closest living relatives, the birds, are

so different that it is hard to make

useful comparisons in many cases.

But, when complete skeletons are

known, all the bones can be identifi ed

from knowledge of living forms, and

the skeleton can be reconstructed.

This usually shows basic things, such

as whether the animal walked on all

fours or on its hind limbs only, what it

ate (are the teeth sharp or not?), and

whether it could have used its hands

for grasping things.

How are paleontologists able to

discern how large a dinosaur is,

and how can they estimate a

dinosaur’s diet?

The dinosaur skeleton will itself be

large or small. The best guide to body

weight for a fossil form is to measure

the leg bones. The femur (thigh bone)

is particularly useful – because

weight (= mass) is a

three-dimensional measure, we look

for something that increases and

decreases in proportion to mass, and

that is the diameter of the femur. So

you get a good relationship between

femur head diameter and body mass

from living birds, crocodiles and

mammals, and dinosaur body

weights can then be estimated from

this regular relationship. Diet is

determined from overall tooth

shape – curved and pointy for

meat-eating, and broader for

plant-eating. It’s hard to be more

precise, because we don’t have the

data set of comparative information

to tell exact plant food from wear

marks and scratches on the tooth

enamel (used for determining the

exact diet of mammals).

What, in your opinion, are the

most important discoveries made

in the past 50 years?

Well, fi rst, the realisation that

dinosaurs were active and dynamic

animals, dating from the work of John

Ostrom in 1969 on Deinonychus, and

Bob Bakker in the Seventies on

dinosaur warm-bloodedness. Second,

the paper by Luis Alvarez and

colleagues in 1980 that showed the

fi rst evidence that the Earth had been

hit by an asteroid 65 million years

ago. This has been much confi rmed

since then, and even the crater has

been identifi ed, all showing the key

role of this in causing the extinction

of the dinosaurs.

Dinosaur identifi cation

We spoke to Mike Benton,

Professor of Vertebrate

Palaeontology in the School of

Earth Science at the Universit y

of Bristol, UK, to find out how

palaeontologists can estimate

the size of a dinosaur from

fossils and more

60m

Amphicoelius Fragillimus

Bruhathkayosaurus Matleyi

Argentinosaurus Huinculensis

Supersaurus Vivianae

Diplodocus Hallorum

Sauroposeidon Proteles

Quetzalcoatlus

Weight: <250kg

Wingspan: 12m (39ft)

Date:

Late Cretaceous (99.6-65.6 Ma)

Group: Pterosaurs

Bigger than: A small plane

The statistics...