![](https://www.nhm.uio.no/english/exhibitions/zoological/endangered-nature/liste-natur-i-nod/sabeltanntiger--red-dsc_2115-crop.jpg)
Fossils, like this skull from the Eurasian dirk toothed cat Xenosmilus, shows species and even ecosystems have been threatened before. Such crisis, whether natural or manmade, primarily hit species that are large, highly specialized or occupy the top of the food chain.
Photo
Karsten Sund/Naturhistorisk museum