Related by context. Frequent words. (Click for all words.) 74 Cretaceous Period 66 Late Cretaceous 65 interglacial period 61 trilobites 61 interglacial 60 Cretaceous 60 Younger Dryas 59 Carboniferous 59 Precambrian 59 Mesozoic 57 dinosaurs 57 Ordovician 57 dinosaurs roamed 57 theropod 56 tyrannosaur 56 Pleistocene 56 marine sediments 56 sedimentary rock 56 Tiktaalik 55 glaciation 55 anatomically modern 55 continental crust 55 fossils 55 multicellular 55 megafauna 55 Triassic 55 Pliocene 55 tetrapods 55 Homo sapiens 54 Archaeopteryx 54 marine reptiles 54 theropods 53 carnivorous dinosaurs 53 tyrannosaurs 53 genus Homo 53 Eocene 53 prehistoric 53 Ardipithecus 53 single celled organisms 53 Little Ice Age 52 Australopithecus afarensis 52 Paleozoic 52 fossilized remains 52 single celled 52 mass extinction 52 hominins 52 Ice Age 52 volcanic islands 52 Australopithecus 52 fossilized bones 51 supernova explosion 51 billed dinosaur 51 sauropod 51 plesiosaur 51 Wilkins Ice Shelf 51 woolly mammoths 51 Quaternary 51 fossil 51 archaea 51 lavas 51 Lower Cretaceous 51 vertebrate species 51 Homo habilis 50 moai 50 mudstone 50 microfossils 50 calcite 50 volcanism 50 prehistory 50 sauropods 50 prehistoric creatures 50 mass extinctions 50 Fertile Crescent 49 mammoths 49 Titan Saturn 49 multicellular organisms 49 taxa 49 oceanic crust 49 bony fish 49 sedimentary rocks 49 Denisovans 49 hadrosaur 49 pterosaur 49 Medieval Warm Period 49 landmasses 49 Holocene 49 lithosphere 49 dinosaur footprints 49 marine invertebrates 49 Homo erectus 49 volcanic crater 49 hominid 49 retreating glaciers 49 Ross Ice Shelf 48 flint tools 48 Proterozoic 48 Jurassic 48 T. rex 48 diatom 48 Neandertal 48 mammals