Related by context. Frequent words. (Click for all words.) 63 Jurassic Period 62 Cretaceous Period 60 dinosaurs roamed 59 Carboniferous 57 Late Cretaceous 56 Cretaceous 55 fossil 54 Mesolithic 54 trilobites 54 Pleistocene 53 Precambrian 52 marine sediments 52 Paleocene 52 microfossils 52 prehistoric 51 dinosaurs 51 fossilized 51 megafauna 51 Pliocene 51 supercontinent 51 angiosperms 50 coprolites 50 fossils 50 Burgess Shale 50 stromatolites 50 Radiocarbon dating 50 Cambrian explosion 50 Younger Dryas 49 sedimentary rock 49 radiocarbon dating 49 middens 49 Columbian mammoth 49 Ordovician 49 temperate forests 49 interglacial 49 interglacial period 49 oxygen isotopes 49 Pleistocene era 49 hadrosaur 49 Ardipithecus ramidus 49 lake sediments 48 marine reptile 48 radiocarbon 48 Mesozoic 48 Ardipithecus 48 marine reptiles 48 Eocene 48 H. erectus 48 Triassic 48 Poinar 48 mammoths 48 Lower Cretaceous 48 fossilized remains 48 periodical cicadas 48 prehistory 47 glaciation 47 continental crust 47 carnivorous dinosaurs 47 millenniums 47 #BC [003] 47 Beringia 47 basaltic 47 Homo sapiens 47 fossilization 47 zircons 47 terrestrial ecosystems 47 Quaternary 47 feathered dinosaurs 47 Industrial Revolution 46 preindustrial 46 isotopic composition 46 isotopic 46 neolithic 46 atmospheric methane 46 magmas 46 barrens 45 ancient Mayans 45 Proterozoic 45 Devonian 45 Silurian 45 woolly mammoths 45 Australopithecus 45 dinosaur footprints 45 volcanic vents 45 Paleozoic 45 African savanna 45 Arctic tundra 45 Jurassic 45 depositional 45 biogenic 45 Medieval Warm Period 45 Paleolithic 45 Fertile Crescent 45 millennia 45 paleo 45 termite mounds 45 ancestors 45 earths 45 Homo habilis 45 degrees Fahrenheit warmer 44 Neandertals