It was not until the Devonian period (419–359 Ma) that we see the first great diversification of fishes living within Australian freshwater basins and in marginal marine embayments. Australia has a rich fossil record of early amphibians which first appeared here around 370–375 Ma, based on well-preserved ‘tetrapod’ trackways at Genoa River, Victoria. The fossil record of reptiles in Australia starts in the Mesozoic Era (250–66 Ma). The oldest of these remains are of Triassic age and comprise a few superficially lizard-like taxa such as prolacertids (eg Kadimakara), and thecodonts. The earliest significant Australian bird fossil is that of a small primitive flying bird (an enantiornithine), known from one leg bone, Nanatius eos, found in 110 Ma marine sediments in Queensland. Two of the world’s three major groups of extant mammals had their origin in the Australian part of the Gondwana supercontinent, the monotremes and marsupials. The oldest mammal fossils from Australia are monotreme fossils from the Cretaceous of Southern Australia. These lived at a time when Australia was part of a small Gondwana (also including Antarctica and New Zealand) which was beginning to drift apart. They are based on isolated jaws and postcranial bones from Lightning Ridge, New South Wales and southern Victoria sites (near Inverloch), dated at between 120 and 110 Ma. Several taxa (Teinolophos, Bishops) existed alongside primitive tribosphenic mammals like Ausktribosphenos.