in tiny organisms die and drift to ttom of to limestone. Among tiny atomic structures ton take to table isotopes—oxygen-16 and oxygen-18.

    (If you ten ope is, it doesn’t matter, t’s an atomrons.) ts come in, for topes accumulate at different rates depending on mosp time of tion. By comparing t ratios, ts can cunningly read conditions in t emperatures, tent and timing of ice ages, and mucopefindings ists can, e entire landscapes t no human eye ever saw.

    to build up so robustly t terrestrial life  muced by giant treeferns and vast sed tead of completely rotting doative matteraccumulated in ric sediments, o t coal bedst sustain mucivity even now.

    tsized groion of asurface animal yet found is a track left 350 million years ago by a millipede-like creature on arock in Scotland. It  long. Before t some millipedes wouldreac.

    itures on t is per surprising t insects in trick t could keep t of tongue s: to fly. Some tookto tion y t t cecime since. t up to ty-fivemiles an antly stop,  far more proportionately tator ten, “ tunnels to see , and despaired.” too, gorged on ts dragonflies grerees and otation liketained outsized proportions. ails and tree ferns greo s of fifty feet, clubmosses to a y.

    t terrestrial vertebrates— land animals from ly because of a sage of relevantfossils, but partly also because of an idiosyncratic Sations and secretive manner ion for almost ury. Jarvik  of a team of Scandinavian sc to Greenland in ticular t lobe-finned fisypet