A Synopsis of Paper 59: The Marine Life Era on Urantia
The billion-year history of Urantia extends through five major eras: the Pre-Life era (Archeozoic), the Life-Dawn era (Proterozoic), the Marine Life era (Paleozoic), the Early Land-Life era (Mezozoic), and the Mammalian era (Cenozoic). At the dawn of the marine‑life period, plants and animals were fairly well distributed throughout the seas and vegetation had begun to move onto the land.
Four hundred million years ago the first multicellular animals suddenly made their appearance. The trilobites evolved and dominated the seas for ages. Periodically, land masses would sink into the oceans and rise again. At times the American land mass was almost entirely submerged. Greenland was warmed by the Gulf Stream. Sediments of conglomerates, limestone, shale, and sandstone were deposited.
Three hundred and sixty million years ago marine life included seaweed, sponges, one-celled organisms, trilobites, and other crustaceans. Of the three thousand varieties of brachiopods appearing at the close of this period, only two hundred have survived into present times.
Three hundred and fifty million years ago saw the beginning of great flood periods on the continents. This age was characterized by enormous amounts of limestone laid down by the lime-secreting algae.
Three hundred and ten million years ago every type of marine life below the vertebrate scale was represented. Sea worms, some types of jellyfish, corals, and sponges evolved. Cephalopods developed and have survived as the modern pearly nautilus, octopus, cuttlefish and squid. Shelled animals were single-shelled and bivalve gastropods-drills, periwinkles, snails, oysters, clams and scallops-and by valve-shelled brachiopods.
Three hundred million years ago another great flood era occurred. The enormous deposits of animal and vegetable matter carried down with this land submergence provided the world with gas, oil, zinc, and lead.
Two hundred and eighty million years ago the continents had largely re-emerged. The trilobites declined. The cephalopods became masters of the seas; some of the larger mollusks grew to be fifteen feet long. Coral-reef formations multiplied. During this age the primitive water scorpions evolved and soon thereafter the first air breathing scorpions appeared.
Two hundred and fifty million years ago vertebrates suddenly appeared in the fish family. The land was rapidly overrun by new orders of vegetation. Ferns appeared suddenly and quickly spread over the face of the earth, some growing to be one hundred feet high. Leafless trees developed. The atmosphere of the earth became enriched with oxygen.
Two hundred and ten million years ago warm‑water seas again covered most of North America and Europe. Out from the warm waters came snails, scorpions, and frogs. Spiders, cockroaches, crickets, locusts, and thirty-inch dragonflies soon followed.
Two hundred million years ago the most active stages of worldwide coal formation were in process.
One hundred and seventy million years ago great evolutionary changes took place. Lands rose and ocean beds sank. The earth's crust folded extensively, and inland lakes and seas evaporated. Two new climatic factors appeared-glaciation and aridity. Thousands of marine animals perished. Of the 100,000 species of life on earth during this era, less than five hundred survived. Harsh weather replaced the mild climate. Insects underwent radical changes to meet the demands of winter and drought.
This period of biologic adversity eliminated all forms of life except those which had survival value. At the close of the marine-life era, the land was largely covered with vegetation, and the atmosphere had become ideal for animal respiration. The vast oceanic nursery of life on Urantia had served its purpose.