How long have these organisms been living on Earth? cockroach nautilus magnolia dragonfly caddis fly shark lungfishmammal

How long have these organisms been living on Earth? cockroach nautilus magnolia dragonfly caddis fly shark lungfishmammal

Extinctions and possibly here Extinctions are relatively common in the geological record. They may be due to single events, like large impacts, or to a combination of effects like changes in world climate and volcanism. However, as you can see, life goes on!

Apatite Apatite is calcium phosphate. These crystals are from Cornwall in the U.K.: the largest crystal is about 4cm long.

DNA DNA is a very large molecule, made up of simpler units repeated billions of times. The sides of the “ladder” are made of alternating sugar and phosphorus units. The rungs of the “ladder” are made up of pairs of bases. There are four types of base to choose from, and the sequence of these 2.85 billion pairs forms the code for life. If you could make a model of DNA with the rungs one centimetre apart, the stretched- out coil would stretch THREE-QUARTERS of the way round the Earth, or from Canberra to Brasilia in South America AND BACK!

Archaean Cyanobacteria, single- celled organisms still living today, flourished in shallow water. They grow in layers to build up sheets, domes and cones by trapping sediment grains or by depositing limy material, making the stromatolites familiar to us in WA. The world’s oldest stromato- lites are found at North Pole, in the Pilbara.

Proterozoic Ediacaran fossils are found in South Australia and in other places world-wide. They are all extinct species but despite their strange appearance, some could have been the ancestors of life on Earth today. A goblet-shaped fossil from around million years ago: up to 5cm long, it has one of the earliest known mineralised skeletons. A metre-long fossil with a mineralised skeleton from around million years ago: it may be related to corals or sponges. These trails on 1.9 billion year-old sands from the Stirling Ranges are thought to have been made by soft-bodied animals!

Cambrian Archaeocyathids, small (8-10cm) and vase-shaped,were filter-feeding creatures which formed great reefs. Trilobites were segmented marine creatures, up to 50cm long which were swimmers, burrowers and bottom dwellers.

Graptolites were colonial animals with horny skeletons, growing to about 10cm long. Ordovician

Silurian Eurypterids were carnivorous marine “sea scorpions”, the first creatures known to walk on land.

Devonian Lungfish First sharks Armoured fish

Carboniferous

Permian Trilobites declined in numbers during the Carboniferous and became extinct by the end of the Permian.

Triassic

Jurassic

Cretaceous

Tertiary

Cenozoic animals These now extinct animals are of Neogene (late Cenozoic) age: some date back to around 15 million years ago. Some may have co-existed with Aborigines.

Neogene: Pleistocene

Holocene Don’t forget that the Holocene includes us!