Author: More than a Dodo

What’s on the van? – Stromatolite

This week’s What’s on the van? comes from Dr Tracy Aze, Museum of Natural History Research Fellow.

This rock called a stromatolite (from the Greek strōma, meaning mattress or bed and lithos meaning rock) is from a very old suite of rocks called the Porsanger Dolomite Formation in Norway, and is at least 542 million years old.

Stromatolites are produced by the activity of ancient blue-green algae, otherwise known as cyanobacteria. The algae are photosynthetic and need good light conditions to allow them to photosynthesise, consequently they live in shallow waters where sunlight can penetrate. They grow in thin mats on the sea floor, which helps them maximise the amount of light they receive. Over time these mats are covered by sediment grains, which block the sunlight and the algae move up through the sediment layer as they migrate back towards the light. This process happens time and time again over many years and the layering that can be seen in this rock is built up as a result.

The algae that produce stromatolites represent some of the earliest life forms on Earth and some deposits have been dated at 3.5 billion years old! Although they are some of our most primitive life forms, communities of these types of algae can still be found living today in shallow warm waters in places such as Western Australia and The Bahamas and visiting these places is thought to be bit like looking through a window to our distant geological past.

What’s on the van? – Oxford Dodo

It’s time for one of the stars of the Museum’s collection! One of our most famous specimens, the dodo even features on our logo.

This week’s What’s on the van? comes from Malgosia Nowak-Kemp, Collections Manager in the Museum’s Life Collections.

The Dodo of Mauritius was discovered in the late sixteenth century by Dutch sailors stopping on the island for water and fresh food supplies. Because of its inability to fly, the Dodo was considered a great exotic curiosity and a few of the birds were shipped to Europe, India and Japan. One of them ended up in London, in the Tradescant collection. This collection, widely known as the “Ark”, was assembled in the seventeenth century by gardeners to the royalty and aristocracy, father and son John Tradescant. The stuffed Dodo was displayed to the public and described in the Tradescants’ catalogue as “Dodar, from the island of Mauritius. It is not able to fly, being so big”.

After the death of the Tradescants, the “Ark” was presented by its new owner, Elias Ashmole, to the University of Oxford, and in 1683 placed in the newly built Ashmolean Museum. Over the years, the specimens suffered from damage inflicted by insect pests and too frequent handling by visitors, and by 1756 only the Dodo’s head and one of its feet remained.

In 1848 it was firmly established that the Dodo was a member of the pigeon order: Columbiformes. In 2002, with application of DNA analysis, the Oxford Dodo yielded even more information about its origin. We now know that several million years ago its ancestors arrived in Mauritius from the Nicobar Islands, off India. Finding no natural enemies in their new habitat, and no competition for food, the lineage evolved in size and gradually lost its ability to fly. But in the end its size was not enough protection to stop humans, and animals introduced by them, like pigs, rats and monkeys, from causing the Dodo’s extinction.