Natural History

The Dodo Skeleton

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The dodo  is the most famous extinct bird. It was discovered in 1627 and extinct by the end of that century. They were only found on the island of Mauritius in the Indian Ocean. These birds were related to pigeons, and their ancestors must have flown to Mauritius a long time before people first reached the island. By the seventeenth century the dodo had evolved into a highly specialised bird and lost the ability to fly.

Dodos spent their lives on the ground where they found their food and built their nests. This worked well for them until 1602 when people introduced other animals to the island. Goats and pigs were introduced to provide food. Sailors did this on many islands so that they could make long voyages across oceans and pick up food along the way. Goats and pigs could have eaten dodo eggs, their chicks and also competed with dodos for food.

Very few pieces of dodos were saved by museums, there is a head in Oxford, a skull in Copenhagen and a beak in Prague. In 1865 an excavation was undertaken in a boggy area of Mauritius by George Clarke, which recovered enough bones to make up a few skeletons. The Royal Dublin Society acquired one of these and it has been on exhibition in their museum ever since. That museum is now the Natural History Museum of the National Museum of Ireland. Some parts of the skeleton were incomplete. The skull is a copy of the Copenhagen specimen and some other parts were modelled in plaster. The specimen is on exhibition with other pigeons, including the extinct passenger pigeon, on the second floor balcony of the Natural History Museum, Merrion Street.

The Brasky Meteorite

3,500,000,000 years old

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When our Solar System formed, there were bits left over and some of these are meteorites. Most of the material in our Solar System is seen in the form of planets and of course the Sun, which is our nearest star. The material that went to make up the planets was controlled by gravity into a large disc orbiting the sun. About five billion years ago (5,000,000,000 years) this material clumped together and formed planets such as Earth. Some material was left over and is found today as blocks of rock known as Asteroids. Most of these are found orbiting the Sun in a path between Mars and Jupiter known as the Asteroid Belt. They solidified about 3,500,000,000 years ago.

If an Asteroid gets close enough to Earth to get pulled in by our gravity, it may fall to the ground as a Meteorite

The Brasky meteorite

The Brasky meteorite is the largest ever known to have fallen in Ireland. It landed in Briska td, Patrickswell, Co Limerick in September 1813. It weighs some 27 kilos and pieces landed nearby were still hot when they were found. Meteorites are essentially bits left over from the formation of the solar system which form bits of rocks known as asteroids which solidified about 3,500,000,000 years ago. Some, like this, orbited too close to the earth and were pulled in by gravity.

 . At least six Meteorites have been seen to fall to the ground in Ireland in the last two centuries, the Brasky Meteorite is the largest at 27 kilos. It fell in 1813 at 9am on 10th September in Briska Townland, between Patrickswell and Adare, County Limerick. Pieces that landed nearby were still hot when found, the group of stones had been seen flying through the air to the sound of 'the most dreadful thunder' which was the breaking of the sound barrier.

Like the majority of meteorites the Brasky example is classed as a Chondrite. This refers to the makeup of the stone, which is a combination of tiny spheres of glassy rock mixed with nickel and iron. The spheres look like mustard seeds (Chondros in Greek) hence their name. The 3-D image here shows the dimpling of the surface in places, which is a feature developed as the surface of the rock melted as it passed through our atmosphere. Air is a dense gas and friction builds up if you move quickly through it, something which astronauts have always had to watch out for. Space ships are controlled so that they enter the atmosphere at just the right angle to avoid burning up, meteorites enter at all sorts of angles and most burn up before they land.

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