mammals

• mammals

59:0.65. The mam­malian era oc­cu­pies the last fifty mil­lion years. This re­cent-times era is known as the Ceno­zoic.

60:1.11Sev­eral mil­lion years later the first mam­mals ap­peared. They were non­pla­cen­tal and proved a speedy fail­ure; none sur­vived. This was an ex­per­i­men­tal ef­fort to im­prove mam­malian types, but it did not suc­ceed on Uran­tia.

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:

61:1.945,000,000 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.

61:1.2Early 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.

61:2.2Al­though the early pla­cen­tal mam­mals sprang from car­niv­o­rous an­ces­tors, very soon her­biv­o­rous branches de­vel­oped, and, ere­long, om­niv­o­rous mam­malian fam­i­lies also sprang up. The an­giosperms were the prin­ci­pal food of the rapidly in­creas­ing mam­mals, the mod­ern land flora, in­clud­ing the ma­jor­ity of pres­ent-day plants and trees, hav­ing ap­peared dur­ing ear­lier pe­ri­ods.

65:2.12It was from an ag­ile lit­tle rep­til­ian di­no­saur of car­niv­o­rous habits but hav­ing a com­par­a­tively large brain that the pla­cen­tal mam­mals sud­denly sprang. These mam­mals de­vel­oped rapidly and in many dif­fer­ent ways, not only giv­ing rise to the com­mon mod­ern va­ri­eties but also evolv­ing into ma­rine types, such as whales and seals, and into air nav­i­ga­tors like the bat fam­ily.