Eocene

61:1.150,000,000 years ago the land ar­eas of the world were very gen­er­ally above wa­ter or only slightly sub­merged. The for­ma­tions and de­posits of this pe­riod are both land and ma­rine, but chiefly land. For a con­sid­er­able time the land grad­u­ally rose but was si­mul­ta­ne­ously washed down to the lower lev­els and to­ward the seas.

61:1.2Early in this pe­riod and in North Amer­ica the pla­cen­tal type of mam­mals sud­denly ap­peared, and they con­sti­tuted the most im­por­tant evo­lu­tion­ary de­vel­op­ment up to this time. Pre­vi­ous or­ders of non­pla­cen­tal mam­mals had ex­isted, but this new type sprang di­rectly and sud­denly from the pre-ex­is­tent rep­til­ian an­ces­tor whose de­scen­dants had per­sisted on down through the times of di­no­saur de­cline. The fa­ther of the pla­cen­tal mam­mals was a small, highly ac­tive, car­niv­o­rous, spring­ing type of di­no­saur.

61:1.3Ba­sic mam­malian in­stincts be­gan to be man­i­fested in these prim­i­tive mam­malian types. Mam­mals pos­sess an im­mense sur­vival ad­van­tage over all other forms of an­i­mal life in that they can:

61:1.41. Bring forth rel­a­tively ma­ture and well-de­vel­oped off­spring.

61:1.52. Nour­ish, nur­ture, and pro­tect their off­spring with af­fec­tion­ate re­gard.

61:1.63. Em­ploy their su­pe­rior brain power in self-per­pet­u­a­tion.

61:1.74. Uti­lize in­creased agility in es­cap­ing from en­e­mies.

61:1.85. Ap­ply su­pe­rior in­tel­li­gence to en­vi­ron­men­tal ad­just­ment and adap­ta­tion.

61:1.945,000,000 years ago the con­ti­nen­tal back­bones were el­e­vated in as­so­ci­a­tion with a very gen­eral sink­ing of the coast lines. Mam­malian life was evolv­ing rapidly. A small rep­til­ian, egg-lay­ing type of mam­mal flour­ished, and the an­ces­tors of the later kan­ga­roos roamed Aus­tralia. Soon there were small horses, fleet-footed rhinoceroses, tapirs with pro­boscises, prim­i­tive pigs, squir­rels, lemurs, opos­sums, and sev­eral tribes of mon­key­like an­i­mals. They were all small, prim­i­tive, and best suited to liv­ing among the forests of the moun­tain re­gions. A large os­trich­like land bird de­vel­oped to a height of ten feet and laid an egg nine by thir­teen inches. These were the an­ces­tors of the later gi­gan­tic pas­sen­ger birds that were so highly in­tel­li­gent, and that one­time trans­ported hu­man be­ings through the air.

61:1.10The mam­mals of the early Ceno­zoic lived on land, un­der the wa­ter, in the air, and among the tree­tops. They had from one to eleven pairs of mam­mary glands, and all were cov­ered with con­sid­er­able hair. In com­mon with the later ap­pear­ing or­ders, they de­vel­oped two suc­ces­sive sets of teeth and pos­sessed large brains in com­par­i­son to body size. But among them all no mod­ern forms ex­isted.

61:1.1140,000,000 years ago the land ar­eas of the North­ern Hemi­sphere be­gan to el­e­vate, and this was fol­lowed by new ex­ten­sive land de­posits and other ter­res­trial ac­tiv­i­ties, in­clud­ing lava flows, warp­ing, lake for­ma­tion, and ero­sion.

61:1.12Dur­ing the lat­ter part of this epoch most of Eu­rope was sub­merged. Fol­low­ing a slight land rise the con­ti­nent was cov­ered by lakes and bays. The Arc­tic Ocean, through the Ural de­pres­sion, ran south to con­nect with the Med­i­ter­ra­nean Sea as it was then ex­panded north­ward, the high­lands of the Alps, Carpathi­ans, Apen­nines, and Pyre­nees be­ing up above the wa­ter as is­lands of the sea. The Isth­mus of Panama was up; the At­lantic and Pa­cific Oceans were sep­a­rated. North Amer­ica was con­nected with Asia by the Bering Strait land bridge and with Eu­rope by way of Green­land and Ice­land. The earth cir­cuit of land in north­ern lat­i­tudes was bro­ken only by the Ural Straits, which con­nected the arc­tic seas with the en­larged Med­i­ter­ra­nean.

61:1.13Con­sid­er­able foraminiferal lime­stone was de­posited in Eu­ro­pean wa­ters. To­day this same stone is el­e­vated to a height of 10,000 feet in the Alps, 16,000 feet in the Hi­malayas, and 20,000 feet in Ti­bet. The chalk de­posits of this pe­riod are found along the coasts of Africa and Aus­tralia, on the west coast of South Amer­ica, and about the West In­dies.

61:1.14Through­out this so-called Eocene pe­riod the evo­lu­tion of mam­malian and other re­lated forms of life con­tin­ued with lit­tle or no in­ter­rup­tion. North Amer­ica was then con­nected by land with ev­ery con­ti­nent ex­cept Aus­tralia, and the world was grad­u­ally over­run by prim­i­tive mam­malian fauna of var­i­ous types.