sea urchins

• sea urchins

60:2.9110,000,000 years ago the po­ten­tials of ma­rine life were con­tin­u­ing to un­fold. The sea urchin was one of the out­stand­ing mu­ta­tions of this epoch. Crabs, lob­sters, and the mod­ern types of crus­taceans ma­tured. Marked changes oc­curred in the fish fam­ily, a stur­geon type first ap­pear­ing, but the fe­ro­cious sea ser­pents, de­scended from the land rep­tiles, still in­fested all the seas, and they threat­ened the de­struc­tion of the en­tire fish fam­ily.

• sea urchins

60:4.5Bi­o­log­i­cally as well as ge­o­log­i­cally this was an event­ful and ac­tive age on land and un­der wa­ter. Sea urchins in­creased while corals and crinoids de­creased. The am­monites, of pre­pon­der­ant in­flu­ence dur­ing a pre­vi­ous age, also rapidly de­clined. On land the fern forests were largely re­placed by pine and other mod­ern trees, in­clud­ing the gi­gan­tic red­woods. By the end of this pe­riod, while the pla­cen­tal mam­mal has not yet evolved, the bi­o­logic stage is fully set for the ap­pear­ance, in a sub­se­quent age, of the early an­ces­tors of the fu­ture mam­malian types.

• sea urchins

65:2.5Be­fore long the early sin­gle-celled an­i­mal types as­so­ci­ated them­selves in com­mu­ni­ties, first on the plan of the Volvox and pres­ently along the lines of the Hy­dra and jel­ly­fish. Still later there evolved the starfish, stone lilies, sea urchins, sea cu­cum­bers, cen­tipedes, in­sects, spi­ders, crus­taceans, and the closely re­lated groups of earth­worms and leeches, soon fol­lowed by the mol­lusks—the oys­ter, oc­to­pus, and snail. Hun­dreds upon hun­dreds of species in­ter­vened and per­ished; men­tion is made only of those which sur­vived the long, long strug­gle. Such non­pro­gres­sive spec­i­mens, to­gether with the later ap­pear­ing fish fam­ily, to­day rep­re­sent the sta­tion­ary types of early and lower an­i­mals, branches of the tree of life which failed to pro­gress.