FACT
Cycads occur across
much of the
subtropical and
tropical parts of the
world including
here in South Africa
where their
evolutionary
importance has
made them a
’protected species’.Figure 11.8: Map of coal deposits in SA: often these deposits are the sites of plant and animal fossils
as they are created by the same process.
”Living fossils” in South Africa: Cycads have been in existence for over 280 million years.
There are several rare species of cycads found exclusively within South Africa. They grow
very slowly and live for up to a 1000 years. Because they are such a rare species, there
are several restrictions on what can be done to them. In South Africa, unless required for
conservation purposes, it is illegal to collect, pluck, destroy, export or possess cycads without
a special permit.
Figure 11.9: Cycads have been in existence for over 280 million years.Mesozoic(251-72 million years ago) DUMMY
TheMesozoic Era is often referred to as the ’age of reptiles’ because throughout the marine
and terrestrial habitats, reptiles (especially dinosaurs) were dominant. This era is divided into
three major periods: Triassic, Jurassic and Cretaceous.
The major events of this era included significant changes in theclimate,evolutionary activity
andland massof Earth.
- The climate of the Mesozoic fluctuated dramatically between cooling and warming
periods. - Until this point, the Earth existed as one giant land mass called Pangaea. During the
Mesozoic era, this land mass broke up, and by the end of the era, the continents as we
know them today drifted into their current positions. - The extinction of nearly all animal species in the former Paleozoic era led to rapid
evolution of many new life forms. - Dinosaurs appeared on land, becoming the major terrestrial vertebrates for nearly 135
million years. - Pterosaurs (flying reptiles) dominated the skies and aquatic reptiles such as ichthyosaurs
were found in the oceans.
Chapter 11. History of Life on Earth 327