Sublime

Archaeothyris—meaning “ancient window”—to highlight the most important feature of this animal: its large, portholelike opening behind its eye, which housed larger and more powerful jaw-closing muscles than its ancestors.

Therians and multituberculates were ensconced in the north, from the Asian heartlands to the North American mountains to the European islands. Among them were insectivores that demolished bugs with their tribosphenic teeth (eutherians), herbivores that feasted on flowers and fruits and other angiosperm parts (multituberculates), and the odd carnivo

specialized genus of cursorial, or hunt-by-chasing, carnivore in the Paleocene, some 60 million years ago.

This was the winter tiger: not the svelte, languorous creature of long grass and jungle pools, but the heavy-limbed sovereign of mountains, snow, and moonlight, resplendent and huge in his cool blue solitude.