Geological age of rocks by animal & plant remains

The is an extensive fossil record dating from the Cambrian (600mya) to the present day. There was a major explosion of multi- celled animal genera during the Cambrian Period -Trilobites, brachiopods, chordata – backboned animals related to increased oxygen. The oldest Pre-Cambrian fossils occur from the Archaean Eon, from 3.4 billion years ago – stromatolites (cyanobacteria) and bacteria. Period Era Period Pre cambrian 600+ mya Palaeozoic mya Mesozoic mya Tertiary (3 rd ) mya Quaternary (4 th ) present

Stromalites in Chert, West AUS Stromalites in Limestone in New Yorek USA

Trilobites were early Arthropods (same group as modern insects and spiders). 3 part body. Marine scavengers Existed from 542 – 251 mya Most had died out by end of (Ordovician) 444 mya, last ones 250 mya

 Ammonites (molluscs that live in a shell spiral shells) – related to modern octopus and squid Devonian 400 mya – Cretaceous 100 mya.  The shell is calcium carbonate, but fossils are usually Iron Pyrites (Iron sulphide)

Lamp shells also called brachiopods. Bivalve filter feeding bottom – dwelling marine shell fish – modern equivalent scallops. Thousands of species. Prominent in Cambrian 540 mya - Triassic 180mya (mass extinction of major genera). Few species exist to quaternary (today)

Diatoms Marine & fresh water algae. Photosynthesise. Cretaceous 150 mya - quaternary. Hard exoskeleton of silica, Size 10 m-150 microns ( millimetres)

Amoeba-like marine animal 1mm or less. Live by scavenging on seafloor sediments. Have a CaCO3 external shell with multiple holes (hole bearers). 275,00 spp living and fossil