Related by context. Frequent words. (Click for all words.) 61 Archaeopteryx 57 Ardipithecus ramidus 55 Halley comet 55 pterosaur 55 Jurassic Period 54 Cretaceous Period 53 Homo habilis 53 feathered dinosaurs 52 hominid 52 supersonic Concorde 51 Nigersaurus 51 theropods 51 Voyager spacecraft 51 carnivorous dinosaurs 51 tyrannosaur 51 comet Wild 50 rover Opportunity 50 hadrosaur 50 Ardipithecus 50 Denisovans 50 H. erectus 50 hominins 50 genus Homo 50 hominin 49 Diplodocus 49 Australopithecus afarensis 49 melanogaster 49 solar nebula 49 pterosaurs 49 Australopithecus 48 tyrannosaurs 48 theropod 48 innermost planet 48 ringed planet 48 Step Pyramid 48 Neandertal 48 Homo erectus 48 Columbian mammoth 48 Burgess Shale 48 Posted -# sec 47 periodical cicadas 47 anatomically modern 47 Tiktaalik 47 Neandertals 47 Radiocarbon dating 47 Beringia 47 Homo sapiens 47 marine reptile 47 vertebrates 47 Titan Saturn 47 tetrapod 47 tetrapods 47 mitochondrial genome 47 New Horizons spacecraft 46 vertebrate 46 supercontinent 46 Brood X 46 globular clusters 46 Cambrian explosion 46 thylacine 46 interglacial period 46 coprolites 46 Messenger spacecraft 46 asteroid Itokawa 46 tyrannosaurus rex 46 dinosaurs 46 T. rex 46 Polar Lander 46 moon Charon 46 angiosperms 46 Poinar 46 Late Cretaceous 46 orbiting telescope 46 rover Spirit 46 giant tortoise 46 planetary nebula 45 common ancestor 45 multicellular organisms 45 anthropoids 45 outer planets 45 Global Surveyor 45 comet nucleus 45 HMS Vanguard 45 mammalian species 45 interplanetary spacecraft 45 microfossils 45 fossil 45 rovers Spirit 45 zircons 45 nematode worms 45 Stardust spacecraft 45 hominids 45 Brachiosaurus 44 fossils 44 Indohyus 44 Tasmanian tiger 44 attained enlightenment 44 vertebrate species 44 ancestor 44 coelacanth 44 Jamestown colony