[lemma=extinct] [!tag=NNS | □]
[lemma=extinct] [!tag=NNS | □=□]
[lemma=extinct] [!tag=NNS | !□]
Other exhibits show extinct animals like the Cape Verde skink , which went extinct sometime in the early 1900s and the skeleton of a dodo bird which went extinct in the 1600s when humans introduced pigs and monkeys onto their relatively predator-free island . The deserted and utterly extinct city of London was under his feet . In the Virgin Islands , the St. Croix tree snake , once common on St. Croix Island , became extinct about 1950 . Strictly speaking , if the world has fairly even diversity through time , existing species will become extinct about as often as new species evolve . Dinosaurs went extinct about 65 million years ago , long before humans were around . Two of the five endemics are either ecologically extinct ( California condor ) or are in need of conservation intervention and management to assure their long-term survival ( Table 7 ) . If the Zayante sand hills habitat were to be reduced to 10 percent of its original extent , one half of all the species found there would be expected to go extinct ( Wilson 1992 ) . ) : families = extinct ( 23 percent ) , living ( 77 percent ) ; genera = living ( 21 percent ) , extinct ( 79 percent ) ; and finally , as for species only 4 percent are living , meaning ... Almost all the large vertebrates on Earth , on land , at sea , and in the air ( all dinosaurs , plesiosaurs , mosasaurs , and pterosaurs ) suddenly became extinct about 65 Ma , at the end of the Cretaceous Period . When therefore we set out to study the events out of which it arose , and the part that its Founder played in them , we are not like archaeologists digging up the remains of a forgotten civilization , or palaeontologists reconstructing an extinct organism . Biologists say up to 90 percent of the surviving population of endangered silvery minnows live below the dam , and if the river dried , the fish could go extinct ( HCN , 10/11/99 : A tiny fish cracks New Mexico ’ s water establishment ) . Analysis of ancient eggshells suggests that the animals suddenly became extinct about 50,000 years ago because people burned up their habitat .