DK - WOW! The Visual Encyclopedia of Everything

Mammoth tooth found

on the bed of the North

Sea shows the sea was

once dry land

173

CENOZOIC ERA (RECENT LIFE)

Non-bird dinosaur fossils do not appear in rock

formed less than 66 million years ago in the

Cenozoic era, showing that they had died out

by that time. Yet mammal fossils become more

varied, and include early relatives of humans,

which date back to 6–7 million years ago. The first

true humans appeared about a million years later.

PALAEONTOLOGY

The word “palaeontology” means the study of ancient

life, preserved as fossils. But palaeontologists also study

non-bony life forms such as molluscs, plants, and even

bacteria. Their work involves carefully removing,

cleaning, and preserving the fossils, as well as identifying

them and recording their features. Special tools ranging

from hammers to medical scanners help them prepare

and interpret their finds.

FOSSILIZATION

Normally only the hard parts of living things,

such as shells and bones, survive as fossils. Over

millions of years these become impregnated with

minerals, so they become stony. Often the original

shell or bone disappear, leaving a mould later filled

by another mineral. Rarely, soft body parts such

as feathers may leave detailed impressions in

fine-grained rock.

Reconstructed fossil

fragments form this

skull of Homo habilis,

an extinct cousin of

modern humans

Fossils from about

10 million years ago reveal

details of ancient corals

Large collections of

specimens help with

the identification and

dating of fossils

Hammer and chisel

used to remove rock

from around fossil

This footprint

of a three-toed

predatory dinosaur is

known as a “trace fossil”

This late Mesozoic clam

left a mould that has

become filled with opal

to create a cast fossil

Split rock reveals the

mineralized fossil of an

ammonite, and a cast

of its shell

Magnifying glass

Opalized

marine snail

Chisels

Geological

hammer

172_173_Fossils.indd 173 03/01/19 12:10 PM