Related by context. Frequent words. (Click for all words.) 54 mass extinction 52 megafauna 51 mass extinctions 51 extinctions 50 dinosaurs 48 tyrannosaurs 48 glaciation 47 theropods 47 Homo floresiensis 46 taxa 46 hominids 46 phylogeny 45 Late Cretaceous 45 radiocarbon dating 45 Australopithecus 45 mammal species 45 tetrapods 45 evolutionary 45 Neandertals 45 pterosaur 44 sauropods 44 amphibian species 44 Ordovician 44 Archaeopteryx 44 vertebrates 44 Homo sapiens 44 speciation 43 evolutionarily 43 mammals 43 Pleistocene 43 species 43 Paabo 43 Pliocene 42 Mesozoic 42 T. rex 42 hominid 42 mammoths 42 Precambrian 42 vertebrate 42 Longrich 42 fossil 42 species extinctions 42 mammalian species 42 fossils 42 palaeontologists 42 woolly mammoths 42 extinction 41 Homo erectus 41 evolutionary biologists 41 sauropod 41 ecosystems 41 palaeontologist 41 biosphere 41 genetic variability 41 lineages 41 thylacine 41 phylogenetic 41 Triceratops 41 archaea 41 radiocarbon 41 evolutionary theory 41 Cretaceous 41 moa 40 herbivore 40 influenza pandemics 40 pterosaurs 40 mammal 40 marine biodiversity 40 clade 40 herbivores 40 plate tectonics 40 amphibians 40 eukaryotes 40 prehistory 40 humans 40 single celled organisms 40 diatoms 40 baleen whales 40 paleoanthropologist 40 Tyrannosaurus rex 39 discoverers 39 penguin species 39 dugongs 39 arthropods 39 T rex 39 fossilized remains 39 fossilized bones 39 common ancestor 39 primate species 38 baiji 38 prion disease 38 Extinction 38 coral species 38 mastodons 38 genetic diversity 38 domestication 38 landmasses 38 frog species 38 evolutionary biology 38 boreal forest 37 forelimbs