Related by context. Frequent words. (Click for all words.) 63 Jurassic Period 61 Cretaceous Period 59 Pleistocene era 57 Late Cretaceous 55 Burgess Shale 54 supercontinent 54 Cambrian explosion 54 interglacial period 52 marine reptile 52 faunal 51 Homo Sapiens 51 wooly mammoth 50 Paleocene 50 Snowball Earth 50 Carboniferous 49 tyrannosaurus rex 49 feathered dinosaurs 49 marine reptiles 49 dinosaurs 49 Palaeolithic 49 stromatolites 49 prehistoric 49 glaciation 49 trilobites 49 dinosaurs roamed 49 Quaternary 49 single celled organisms 49 Radiocarbon dating 48 Ardipithecus ramidus 48 limestone cave 48 tyrannosaur 48 hydrothermal vent 48 interglacial 48 Pleistocene 48 fossilization 48 marine sediments 48 multicellular 48 megafauna 48 Indohyus 47 Inca Empire 47 Khmer empire 47 Homo sapiens 47 Tiktaalik 47 Beringia 47 Fertile Crescent 47 millenniums 47 single celled 47 Mesozoic 47 Siberian permafrost 47 placental mammals 47 Ice Age 47 vertebrate animals 47 melting glacier 47 Cretaceous 47 Cro Magnon 47 tyrannosaurs 47 Siddhartha Gautama 47 glaciations 47 Precambrian 47 Amazonian rainforest 47 African savanna 46 saber toothed tigers 46 Lapita 46 classical antiquity 46 Pliocene 46 Oetzi 46 H. erectus 46 Mayan civilization 46 Otzi 46 prehistory 46 Younger Dryas 46 Australopithecus 46 Lake Vostok 46 tetrapod 46 giant tortoise 46 Columbian mammoth 46 ground sloths 46 Paleolithic 46 relict 46 preindustrial 45 fossilized 45 Neandertal 45 theropod 45 limestone caves 45 Egyptian pharaoh 45 multicellular organisms 45 lava tubes 45 Eocene 45 hadrosaur 45 Ordovician 45 radiocarbon dated 45 temperate forests 45 subarctic 45 Lascaux 45 ancient Mayans 44 anatomically modern 44 Neanderthal 44 retreating glaciers 44 microfossils 44 plesiosaur 44 fossils