Related by context. Frequent words. (Click for all words.) 60 Late Cretaceous 57 Pleistocene 56 multicellular 55 glaciation 54 Precambrian 54 Holocene 54 Cretaceous 53 fossils 53 megafauna 53 Pliocene 51 mass extinctions 51 Eocene 51 Mesozoic 51 Ordovician 50 millenniums 50 volcanism 50 mammals 50 single celled 50 single celled organisms 50 mass extinction 49 radiocarbon 49 Homo sapiens 49 diatoms 48 landforms 48 Triassic 48 mammal 47 vertebrate species 47 fossil 47 tetrapods 47 prehistory 47 desiccation 47 millennia 47 Fertile Crescent 47 archaea 47 Microorganisms 47 radiocarbon dating 47 hominid 47 biota 47 plate tectonics 46 hydrothermal vents 46 mammoths 46 lichens 46 tyrannosaurs 46 anoxic 46 fossilized 46 Paleolithic 46 vertebrate 45 Paleozoic 45 woolly mammoths 45 palaeontologists 45 geologic 45 microscopic organisms 45 lake sediments 45 primordial soup 45 hominids 45 anatomically modern 45 Fossils 45 vertebrates 45 species 45 Australopithecus 45 flowering plants 44 diatom 44 Tibetan Plateau 44 radioactive decay 44 hunter gatherers 44 sedimentary rock 44 sediment cores 44 Homo habilis 44 Oligocene 44 prehistoric 44 Medieval Warm Period 44 taxa 44 sediments 44 aquatic creatures 44 dinosaurs 44 fossilized remains 44 Little Ice Age 43 homo sapiens 43 organisms 43 PETM 43 volcanic islands 43 landmasses 43 nitrogen fixation 43 Neandertals 43 larval stage 43 accreted 43 continental drift 43 journal Geology 43 dinosaur fossils 43 fossilized bones 43 Australopithecus afarensis 43 millenia 43 organic molecules 43 biosphere 43 intertidal 43 basalts 43 Neolithic 43 Archaeopteryx 43 geologically 43 plesiosaur 43 humans