Fossils from the dawn of life

‘We are about to time travel back to other worlds,’ says broadcaster and author Gaia Vince as she introduces a selection of stunning fossils offered in our Science and Natural History sale in London on 10 July. In fact, we’re going all the way back to when ‘the flourishing of life began’.

The first piece Vince looks at is a beautiful specimen of tiger iron, one of the earliest fossilised forms of life from a time, more than two billion years ago, when the newly formed continents were barren and life was confined to the seas.

Tiger iron gets its name from its distinctive stripes of gold and deep red, which scientists have suggested were caused by a banded iron formation (layered sediments caused by photosynthetic cyanobacteria) or a Stromatolite (layers of algae), or even both. Simple photosynthesising life forms such as these dominated the first two billion years of life on Earth, and were probably the first source of the oxygen in the atmosphere.

‘It looks like a work of art,’ says Vince of this sea lily, or feather star, which is not actually a plant but a filter feeder from the same family as sea urchins and starfish.

With crowns of pinnules that trapped the microscopic particles it fed on, sea lilies swayed back and forth on the ocean floor. Their fossil remains are found all over the world, but the most beautiful and best preserved examples are those from the Posidonia shale beds of Holzmaden in southern Germany.

Crocodiles, explains Vince, are ‘one of the success stories of the Jurassic’. Whereas dinosaurs died out in a mass extinction, crocodiles survived, although how they did so is still a topic of debate. One theory is that, unlike dinosaurs, they were cold-blooded, and therefore were able to survive on less food after the great asteroid impact and the climate change that followed it.

Since 1825, at least 12 species have been found in sites across Europe and Morocco. The long snout with sharp teeth on this example suggests a diet of predominantly  small fish, while the preservation of armoured scutes to the body hint at a combative lifestyle in the coastal waters of the Tethys Ocean some 180 million years ago.

‘This is the real Jurassic Park,’ enthuses James Hyslop, Head of the Science & Natural History department at Christie’s, as he admires two 150 million-year-old pterosaur skeletons from the Jurassic — both offered in the sale.

‘Most fossils that you find are fragmentary but this is about 98 per cent complete,’ he explains of the first. A lightweight body with hollow bones made Rhamphorhyncus muensteri  perfectly adapted to life in the air above the Jurassic coast. On very rare occasions they fell into lagoons below where they were preserved by the mud and, over millions of years, ultimately turned to stone.

Hylsop describes the fossil of the Germanodactylus, above, as ‘incredibly rare’. Only four are known to exist, all of which are in museums. This example has the largest recorded wingspan of them all, estimated at 55 inches.

Originally classified as a new species of pterodactyl when first discovered in 1901, these winged lizards were subsequently renamed. The specialist explains that he immediately knew what this skeleton was from its distinctive head crest. 

Although it looks like a dolphin, the ichthyosaur above is actually a reptile — ‘a fast swimmer and top predator’, according to Hyslop. The preservation of stomach contents, which can be seen in this example, is very rare in the fossil record. ‘It's a very visual, very beautiful piece,’ says the specialist.

The first complete ichthyosaur skeleton was found at Lyme Regis, England, in 1811, and today about 80 species are recognised. They take their name from the Greek for ‘fish lizards’.