Related by context. Frequent words. (Click for all words.) 64 Pleistocene 60 glaciation 58 mammoths 57 Ice Age 56 Homo sapiens 55 Little Ice Age 53 dinosaurs 53 woolly mammoths 53 Neanderthals 52 Cretaceous 50 woolly mammoth 50 mass extinction 49 homo sapiens 49 hunter gatherers 49 prehistoric 49 hominids 49 Holocene 48 Paleolithic 48 prehistory 47 Mayan civilization 47 Neanderthal 47 Homo erectus 47 hunter gatherer 47 mastodons 47 hominid 46 Triassic 46 Eocene 46 Precambrian 45 epochs 44 millenniums 44 Bronze Age 44 glacial 44 mass extinctions 44 millennia 44 permafrost 44 fossils 44 Dark Ages 43 Ellesmere Island 43 fossilized remains 43 epoch 42 extinct 42 Arctic tundra 42 domesticated 41 paleontological 41 Bering Strait 41 Han Dynasty 41 domestication 41 plate tectonics 41 Neolithic 41 Archaeopteryx 41 fossil 41 Bolshevik revolution 41 Jurassic 40 fossilized 40 radiocarbon dating 40 radiocarbon 40 palaeontologists 40 dinosaur 40 Roman Empire 40 extinctions 40 Industrial Revolution 40 civilization 39 humans 39 mastodon 39 volcanism 39 common ancestor 39 northern latitudes 39 Antarctica 39 tundra 39 sauropods 39 greenhouse warming 39 Cold War 39 diatoms 39 vertebrates 39 extinction 39 paleo 39 glaciers 39 inhabited 39 Dinosaurs 39 PETM 39 lineages 39 Antarctic Peninsula 39 extinct species 38 Prehistoric 38 arctic 38 Gondwana 38 taxa 38 Anasazi 38 eukaryotes 38 twentieth century 38 eons 38 sauropod 38 atmospheric CO2 38 Devonian 38 Antarctic 38 millenia 38 Mesoamerica 38 mammals 38 geologic 37 Hellenistic 37 T. rex