Why don't scientists go mining in the Arctic or Antarctic for complete specimens of Mammoths or maybe even Dinosaurs?

the Arctic and Antarctic have never had conditions conducive to the establishment of large herbivores (what with the 6-month night every year), so it would be unlikely that anything would be found. Some mammoths have been found frozen in subarctic permafrost, so no need to go looking in odd places.

Skeletons are the best you could hope to find for dinosaurs, or 'cast' fossils. They would not have lived in environments cold enough to preserve them by freezing, so only the bones survive, and/or impressions in the surrounding rock.

And just where would you look? There is not enough time to dig up *everything*.

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If you have few million to donate, they will. Please don't use the tax payers money.

Who says they are not?