dinosaurs

60:1.10These rapidly evolv­ing rep­til­ian di­no­saurs soon be­came the monar­chs of this age. They were egg lay­ers and are dis­tin­guished from all an­i­mals by their small brains, hav­ing brains weigh­ing less than one pound to con­trol bod­ies later weigh­ing as much as forty tons. But ear­lier rep­tiles were smaller, car­niv­o­rous, and walked kan­ga­roo­like on their hind legs. They had hol­low avian bones and sub­se­quently de­vel­oped only three toes on their hind feet, and many of their fos­sil foot­prints have been mis­taken for those of gi­ant birds. Later on, the her­biv­o­rous di­no­saurs evolved. They walked on all fours, and one branch of this group de­vel­oped a pro­tec­tive ar­mor.

60:2.1120,000,000 years ago a new phase of the rep­til­ian age be­gan. The great event of this pe­riod was the evo­lu­tion and de­cline of the di­no­saurs. Land-an­i­mal life reached its great­est de­vel­op­ment, in point of size, and had vir­tu­ally per­ished from the face of the earth by the end of this age. The di­no­saurs evolved in all sizes from a species less than two feet long up to the huge non­car­niv­o­rous di­no­saurs, sev­enty-five feet long, that have never since been equaled in bulk by any liv­ing crea­ture.

60:2.2The largest of the di­no­saurs orig­i­nated in west­ern North Amer­ica. These mon­strous rep­tiles are buried through­out the Rocky Moun­tain re­gions, along the whole of the At­lantic coast of North Amer­ica, over west­ern Eu­rope, South Africa, and In­dia, but not in Aus­tralia.

60:2.3These mas­sive crea­tures be­came less ac­tive and strong as they grew larger and larger; but they re­quired such an enor­mous amount of food and the land was so over­run by them that they lit­er­ally starved to death and be­came ex­tinct—they lacked the in­tel­li­gence to cope with the sit­u­a­tion.

60:2.4By this time most of the east­ern part of North Amer­ica, which had long been el­e­vated, had been lev­eled down and washed into the At­lantic Ocean so that the coast ex­tended sev­eral hun­dred miles far­ther out than now. The west­ern part of the con­ti­nent was still up, but even these re­gions were later in­vaded by both the north­ern sea and the Pa­cific, which ex­tended east­ward to the Dakota Black Hills re­gion.

60:2.5This was a fresh-wa­ter age char­ac­ter­ized by many in­land lakes, as is shown by the abun­dant fresh-wa­ter fos­sils of the so-called Mor­ri­son beds of Col­orado, Mon­tana, and Wyoming. The thick­ness of these com­bined salt- and fresh-wa­ter de­posits varies from 2,000 to 5,000 feet; but very lit­tle lime­stone is pres­ent in these lay­ers.

60:2.6The same po­lar sea that ex­tended so far down over North Amer­ica like­wise cov­ered all of South Amer­ica ex­cept the soon ap­pear­ing An­des Moun­tains. Most of China and Rus­sia was in­un­dated, but the wa­ter in­va­sion was great­est in Eu­rope. It was dur­ing this sub­mer­gence that the beau­ti­ful litho­graphic stone of south­ern Ger­many was laid down, those strata in which fos­sils, such as the most del­i­cate wings of olden in­sects, are pre­served as of but yes­ter­day.

60:2.10This con­tin­ued to be, pre-em­i­nently, the age of the di­no­saurs. They so over­ran the land that two species had taken to the wa­ter for sus­te­nance dur­ing the pre­ced­ing pe­riod of sea en­croach­ment. These sea ser­pents rep­re­sent a back­ward step in evo­lu­tion. While some new species are pro­gress­ing, cer­tain strains re­main sta­tion­ary and oth­ers grav­i­tate back­ward, re­vert­ing to a for­mer state. And this is what hap­pened when these two types of rep­tiles for­sook the land.

60:2.12Soon af­ter two species of di­no­saurs mi­grated to the wa­ter in a fu­tile at­tempt at self-preser­va­tion, two other types were driven to the air by the bit­ter com­pe­ti­tion of life on land. But these fly­ing pterosaurs were not the an­ces­tors of the true birds of sub­se­quent ages. They evolved from the hol­low-boned leap­ing di­no­saurs, and their wings were of bat­like for­ma­tion with a spread of twenty to twenty-five feet. These an­cient fly­ing rep­tiles grew to be ten feet long, and they had sep­a­ra­ble jaws much like those of mod­ern snakes. For a time these fly­ing rep­tiles ap­peared to be a suc­cess, but they failed to evolve along lines which would en­able them to sur­vive as air nav­i­ga­tors. They rep­re­sent the non­sur­viv­ing strains of bird an­ces­try.

60:3.2060,000,000 years ago, though the land rep­tiles were on the de­cline, the di­no­saurs con­tin­ued as monar­chs of the land, the lead now be­ing taken by the more ag­ile and ac­tive types of the smaller leap­ing kan­ga­roo va­ri­eties of the car­niv­o­rous di­no­saurs. But some­time pre­vi­ously there had ap­peared new types of the her­biv­o­rous di­no­saurs, whose rapid in­crease was due to the ap­pear­ance of the grass fam­ily of land plants. One of these new grass-eat­ing di­no­saurs was a true quadruped hav­ing two horns and a cape­like shoul­der flange. The land type of tur­tle, twenty feet across, ap­peared as did also the mod­ern croc­o­dile and true snakes of the mod­ern type. Great changes were also oc­cur­ring among the fishes and other forms of ma­rine life.

60:3.21The wad­ing and swim­ming pre­birds of ear­lier ages had not been a suc­cess in the air, nor had the fly­ing di­no­saurs. They were a short-lived species, soon be­com­ing ex­tinct. They, too, were sub­ject to the di­no­saur doom, de­struc­tion, be­cause of hav­ing too lit­tle brain sub­stance in com­par­i­son with body size. This sec­ond at­tempt to pro­duce an­i­mals that could nav­i­gate the at­mo­sphere failed, as did the abortive at­tempt to pro­duce mam­mals dur­ing this and a pre­ced­ing age.

61:2.5On land this was pre-em­i­nently the age of mam­malian ren­o­va­tion and ex­pan­sion. Of the ear­lier and more prim­i­tive mam­mals, over one hun­dred species were ex­tinct be­fore this pe­riod ended. Even the mam­mals of large size and small brain soon per­ished. Brains and agility had re­placed ar­mor and size in the prog­ress of an­i­mal sur­vival. And with the di­no­saur fam­ily on the de­cline, the mam­mals slowly as­sumed dom­i­na­tion of the earth, speed­ily and com­pletely de­stroy­ing the re­main­der of their rep­til­ian an­ces­tors.

61:2.6Along with the dis­ap­pear­ance of the di­no­saurs, other and great changes oc­curred in the var­i­ous branches of the saurian fam­ily. The sur­viv­ing mem­bers of the early rep­til­ian fam­i­lies are tur­tles, snakes, and croc­o­diles, to­gether with the ven­er­a­ble frog, the only re­main­ing group rep­re­sen­ta­tive of man’s ear­lier an­ces­tors.

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.

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.

60:2.13Tur­tles in­creased dur­ing this pe­riod, first ap­pear­ing in North Amer­ica. Their an­ces­tors came over from Asia by way of the north­ern land bridge.

60:2.14One hun­dred mil­lion years ago the rep­til­ian age was draw­ing to a close. The di­no­saurs, for all their enor­mous mass, were all but brain­less an­i­mals, lack­ing the in­tel­li­gence to pro­vide suf­fi­cient food to nour­ish such enor­mous bod­ies. And so did these slug­gish land rep­tiles per­ish in ever-in­creas­ing num­bers. Hence­forth, evo­lu­tion will fol­low the growth of brains, not phys­i­cal bulk, and the de­vel­op­ment of brains will char­ac­ter­ize each suc­ceed­ing epoch of an­i­mal evo­lu­tion and plan­e­tary prog­ress.