How long have these organisms been living on Earth?

1. How long have these organisms been living on Earth? caddis fly cockroach nautilus dragonfly lungfish mammal magnolia shark 545 490 434 410 354 298 251 205 141 65 2

2. How long have these organisms been living on Earth? caddis fly cockroach nautilus dragonfly lungfish mammal magnolia shark 545 490 434 410 354 298 251 205 141 65 2

3. Extinctions 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! and possibly here

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

5. 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!

6. 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. 4600 3400 3000 2500 1600 1000 545 251 65

7. Proterozoic A goblet-shaped fossil from around 560-550 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 560-550 million years ago: it may be related to corals or sponges. 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. These trails on 1.9 billion year-old sands from the Stirling Ranges are thought to have been made by soft-bodied animals! 4600 3400 3000 2500 1600 1000 545 251 65

8. 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. 545 490 434 410 354 298 251 205 141 65 2

9. Ordovician Graptolites were colonial animals with horny skeletons, growing to about 10cm long. 545 490 434 410 354 298 251 205 141 65 2

10. Silurian Eurypterids were carnivorous marine “sea scorpions”, the first creatures known to walk on land. 545 490 434 410 354 298 251 205 141 65 2

11. Devonian Armoured fish Lungfish First sharks 545 490 434 410 354 298 251 205 141 65 2

12. Carboniferous 545 490 434 410 354 298 251 205 141 65 2

13. Permian Trilobites declined in numbers during the Carboniferous and became extinct by the end of the Permian. 545 490 434 410 354 298 251 205 141 65 2

14. Triassic 545 490 434 410 354 298 251 205 141 65 2

15. Jurassic 545 490 434 410 354 298 251 205 141 65 2

16. Cretaceous 545 490 434 410 354 298 251 205 141 65 2

17. Tertiary 545 490 434 410 354 298 251 205 141 65 2

18. 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. 545 490 434 410 354 298 251 205 141 65 2

19. Neogene: Pleistocene 545 490 434 410 354 298 251 205 141 65 2

20. Holocene Don’t forget that the Holocene includes us! 545 490 434 410 354 298 251 205 141 65 2