Page 54 - Dinosaur (DK Eyewitness Books)

Ancient footprints

A ȥȪȯȰȴȢȶȳ ȸȢȭȬȪȯȨ by a river, lake, or sea
sometimes left its footprints in soft mud that quickly
dried and hardened. Buried by successive layers
of mud, this slowly turned to rock, preserving the
footprints inside it as fossils. The shapes and sizes
of such prints and the gaps between them can help
scientists to identify different types of track-makers,
and also work out the sizes of the dinosaurs and
how fast they walked or ran. Scientists can even
tell where a dinosaur hunted, or where a herd
trekked together. People find fossil dinosaur
tracks all over the world. They give us glimpses
of dinosaurs’ lives that we could never get by
just studying their bones.

THUNDER FOOT
This fossil sauropod footprint
dwarfs a human hand. Parallel
rows of washtub-sized depressions
like this one pockmark rocks at
Purgatoire in Colorado. They
tell us that a herd of diplodocid
dinosaurs (huge sauropods with
a long neck and long tail) passed
by some time late in the Jurassic
Period. Scientists were not sure
precisely which dinosaur made the
gigantic Purgatoire prints, so they
gave it a special name—Brontopodus,
meaning “thunder foot.”

Ilium
(hip bone)

Inner toe print

Small dinosaur’s
Wet surface
hindfeet leave lighter
layer of mud
impressions on mud
Hip height Mudflat
Length
FOSSIL TRACKS
Iguanodon of foot Dinosaurs left behind more fossil footprints
skeleton
than fossil bones. Scientists have identified
Large dinosaur’s
150,000 tracks in a square patch of land, half
hindfoot makes
CALCULATING SIZE a mile (1 km) across, at a site in Wyoming.
deep impression
An Iguanodon might have measured anything Dinosaurs churned up the ground so heavily
from 26 to 40 ft (8–12 m) in length. Scientists can that tracing individual footprints can be MAKING FOOTPRINTS
estimate a dinosaur’s size from just its footprints, impossible. Even where prints show up clearly, 1A small two-legged dinosaur and large
without even seeing its fossil bones. Multiplying some can be misleading. As shown here, four-legged dinosaur are seen crossing a mudflat.
the size of a footprint by four gives an idea of the the survival of only the hindfeet prints of a Both leave footprints on the surface, but only the
dinosaur’s hip height. Scientists can then work four-legged dinosaur might incorrectly suggest large dinosaur’s hindfeet are heavy enough to make
out the likely length of the whole animal. that they came from a two-legged dinosaur. dents in the firmer layer of mud lying beneath.
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