Related by context. Frequent words. (Click for all words.) 68 Late Cretaceous 64 Cretaceous Period 64 Jurassic Period 63 Cretaceous 63 Carboniferous 62 Mesozoic 62 Ordovician 61 Triassic 61 Paleocene 61 Burgess Shale 60 trilobites 60 marine reptiles 59 Eocene 59 Jurassic 58 Paleozoic 57 Lower Cretaceous 57 interglacial period 57 Pliocene 57 interglacial 57 dinosaurs 57 Oligocene 56 Precambrian 56 lava tubes 55 Miocene 55 Cambrian explosion 55 Pleistocene 55 Upper Cretaceous 55 hydrothermal vent 54 limestone caves 54 supercontinent 54 prehistoric 54 planktonic 53 Dinosaurs Alive 53 Devonian 53 Proterozoic 53 fossils 53 Silurian 53 geologic 52 Brachiosaurus 52 dinosaur skeletons 52 Ngorongoro Crater 52 fossilized remains 52 igneous rocks 51 Pleistocene era 51 Quaternary 51 sedimentary rocks 51 schists 51 woolly mammoths 51 comet Wild 50 prehistoric creatures 50 continental crust 50 basalts 50 feathered dinosaurs 50 foraminifera 50 unconformity type 50 megafauna 50 dinosaurs roamed 50 Valles Marineris 50 depositional 50 Palaeolithic 50 Ardipithecus ramidus 50 Younger Dryas 50 tyrannosaurs 50 stromatolites 50 banded iron 50 tyrannosaur 50 Allosaurus 50 Australopithecus 49 sauropods 49 sedimentary rock 49 tuffs 49 Triceratops 49 Archean 49 glaciation 49 limestones 49 African savanna 49 massive sulphide deposits 49 mammals 49 basaltic 49 oceanic crust 49 carnivorous dinosaurs 49 landforms 49 Polar Regions 49 caldera 49 arthropods 49 hydrothermal activity 49 theropod 49 radiometric anomaly 49 tetrapod 49 interbedded 49 lavas 49 Frankfield East 49 graben 49 geologically 49 intrusives 49 marine sediments 49 fossil 48 Lake Vostok 48 dinos 48 marine reptile 48 volcanogenic massive sulphide