Wood and plants

When strange conifers and ferns covered the earth

Fossilised wood

Fossilised wood is often found along the Jurassic Coast, usually having been washed into the sea from the land. We also have entire fossil forests at Lulworth and the Isle of Portland, dating back 140 million years. The wood has been so well preserved that you can even count the growth rings on the trunks.

Types of trees

Cycad fossil
Cycad fossil

The main trees that grew here in the Triassic, Jurassic and early Cretaceous periods were conifers, like the cypress and monkey puzzle tree. One group, the podocarps, can still be found growing in the ancient forests of New Zealand, Australia and South America. They date back 140 million years, to the time when most of the landmasses in today’s Southern Hemisphere, including Antarctica, South America, Africa, Madagascar and Australia, formed a supercontinent called Gondwana.

Also abundant back then were exotic fern-like plants called cycads and tree ferns, although both looked different to today’s ferns and palm trees. A cycad fossil is shown on the right.

Dinosaur diet

Plant life in the time of the dinosaurs was very different from today. Almost all of our trees are flowering plants, whether producing catkins or full blooms. Ancient species produced spores or cones such as ferns, mosses and conifers. So, even if we could re-create dinosaurs as in the Jurassic Park films, they would hardly recognise any modern plants, even grass – making it extremely difficult to feed them!

How wood is fossilised

Wood can be fossilised in a number of ways:

Concrete roots!

Rhizoconcretions
Rhizoconcretions

RhizoconcretionsIn East Devon, you can see upright pillars in the rocks. These are fossilised roots known as rhizoconcretions (shown right). The roots would have drawn water out of the ground in baking desert conditions, and the calcium and salt in the water gradually formed a cast around the roots.

Impossible preservation

In very fine muds and silts even leaves can be preserved. The best are from the Bournemouth Plant Beds which at just 55 million years in age, lie well within the age of flowering plants which is why the leaves look so familiar to us.

Fossilised leaf