Paper 60 Overview: Urantia During the Early Land-Life Era

This paper chronicles the transformative geological and biological epochs that defined earth's transition from marine-dominated life to terrestrial ecosystems, spanning approximately 150 to 50 million years ago. Beginning with the early reptilian age through the later reptilian dominance, the Cretaceous flowering-plant period, and concluding with the end of the Chalk period, this narrative documents the complex interplay between geological processes and biological evolution. The text meticulously details continental movements, mountain formations, sea invasions, and climate variations that collectively created the conditions for significant evolutionary developments.

The evolutionary account documents the emergence and dominance of reptiles, particularly dinosaurs, whose reign lasted approximately 45 million years before their extinction, attributed to their inability to adapt despite their physical supremacy. The paper tracks the appearance of primitive mammals, the sudden emergence of flowering plants, the evolution of birds directly from reptilian ancestors, and the gradual replacement of fern forests with modern coniferous and deciduous trees. Throughout these periods, the planet underwent dramatic geographical transformations, including the formation of the Rocky Mountains, Sierras, and Andes, that established the foundational geology for subsequent mammalian evolution, leading toward the eventual appearance of human life.

The era of exclusive marine life has ended. Land elevation, cooling crust and cooling oceans, sea restriction and consequent deepening, together with a great increase of land in northern latitudes, all conspired greatly to change the world's climate in all regions far removed from the equatorial zone.

The closing epochs of the preceding era were indeed the age of frogs, but these ancestors of the land vertebrates were no longer dominant, having survived in greatly reduced numbers. Very few types outlived the rigorous trials of the preceding period of biologic tribulation. Even the spore-bearing plants were nearly extinct.

The erosion deposits of this period were predominantly composed of conglomerates, shale, and sandstone, with gypsum and red layers throughout these sedimentations across both America and Europe, indicating an arid climate. These arid districts experienced substantial erosion from violent and periodic cloudbursts originating in the surrounding highlands, reshaping the landscape through these episodic but intense hydrological events. Fossil evidence from this period remains sparse, with most documentation coming from sandstone footprints of land reptiles rather than preserved organic remains, particularly in regions where thousand-foot red sandstone deposits contain virtually no fossils. Significantly, terrestrial animal life maintained continuity only in specific regions of Africa, demonstrating the geographically constrained nature of early land-based evolutionary development.

The thickness of these geological deposits varies dramatically from 3,000 to 10,000 feet, reaching extraordinary depths of 18,000 feet along the Pacific coast, illustrating the magnitude of sedimentary accumulation during this period. Volcanic activity introduced lava between many of these stratified layers, forming distinctive geological features such as the Palisades of the Hudson River through basalt extrusion between Triassic strata. Similar deposits from this period can be found across Europe, particularly in Germany and Russia, while England preserves evidence in its New Red Sandstone formations. The southern Alps feature limestone deposits resulting from sea invasions, now visible as distinctive dolomite limestone formations that extend throughout Africa and Australia, including the famous Carrara marble, which originated as modified limestone during this period.

Approximately 150 million years ago, the early land-life periods of earth's history commenced, with life generally faring better than during the hostile conclusion of the marine-life era. The planetary geography underwent significant reconfiguration, with eastern and central North America, northern South America, most of Europe, and all of Asia elevated above water level. North America experienced its first geographical isolation, though this separation proved temporary as the Bering Strait land bridge soon reconnected it with Asia. Major geological formations developed during this period, including extensive troughs paralleling the Atlantic and Pacific coasts and the significant eastern-Connecticut fault, where one side eventually subsided two miles. Over time, many of these North American troughs filled with erosion deposits, as did numerous freshwater and saltwater lake basins in mountainous regions, which were later dramatically elevated by subterranean lava flows, preserving the petrified forests found in various regions today.

Approximately 120 million years ago initiated a new phase of reptilian evolution characterized by the development and subsequent decline of dinosaurs. This period witnessed land animal life reaching its zenith in terms of physical scale, followed by the near-complete extinction of dinosaurian species by the era's conclusion. The dinosaurs evolved across an extraordinary size spectrum, ranging from species less than two feet in length to the massive non-carnivorous varieties reaching seventy-five feet, establishing a biological mass threshold that has remained unsurpassed by any subsequent terrestrial organism. Their fossilized remains are distributed throughout the Rocky Mountain regions, along the entire Atlantic coast of North America, across western Europe, South Africa, and India, though notably absent from Australia, indicating specific continental patterns of dinosaurian habitation and migration.

These colossal reptiles exhibited an inverse relationship between size and physiological efficiency, becoming progressively less active and robust as their dimensions increased. Their enormous nutritional requirements, coupled with their widespread population density, ultimately created an unsustainable ecological situation in which they effectively depleted their food resources beyond recovery. The dinosaurs' fundamental limitation proved to be intellectual rather than physical: they lacked sufficient neurological complexity to address their ecological crisis, resulting in their starvation and extinction. This period coincided with significant geographical reconfigurations, particularly the erosion and submergence of eastern North America, whose landmass was substantially diminished and coastline extended hundreds of miles beyond its current position, while the western regions remained elevated but experienced periodic invasions from northern seas and the Pacific, which extended eastward to the Dakota Black Hills.

This era was predominantly characterized by freshwater environments, as evidenced by the abundant freshwater fossil deposits in the Morrison beds across Colorado, Montana, and Wyoming. These combined salt and freshwater deposits range from 2,000 to 5,000 feet in thickness, though with minimal limestone presence, suggesting specific hydrological and chemical conditions. Concurrent with North American developments, global submergence patterns were emerging, with the same polar sea that extended over North America also covering most of South America, except for the nascent Andes Mountains. Chinese and Russian territories experienced significant inundation, though the water invasion reached its greatest extent in Europe, resulting in the formation of Germany's lithographic stone, which preserved remarkably detailed fossils, including delicate insect wing structures, with extraordinary fidelity.

The Cretaceous period derives its nomenclature from the predominance of chalk-producing foraminifers that proliferated in the seas during this epoch. This period represents a critical juncture in earth's biological narrative, marking the approaching conclusion of reptilian dominance while witnessing the emergence of flowering plants and avian life forms on land. This era coincided with the termination of westward and southward continental drift, accompanied by tremendous crustal deformations, extensive lava flows, and widespread volcanic activity across the planet. As the preceding geologic period concluded, substantial continental landmass remained above sea level, but the continuing continental drift encountered significant resistance from the deep Pacific Ocean floor, initiating the formation of the vast north-south mountain range extending from Alaska through Mexico to Cape Horn.

This period constitutes the modern mountain-building stage of geologic history, contrasting with earlier epochs when few mountain peaks existed and elevated land typically formed broad, extensive ridges. The Pacific coast range began its formation approximately 700 miles west of the present shoreline, while the Sierra Nevada mountains commenced their development, with gold-bearing quartz strata originating from contemporaneous lava flows. Approximately 100 million years ago, North America and parts of Europe were significantly elevated above sea level, while continued warping of the American continents resulted in the metamorphosis of the South American Andes and gradual elevation of North America's western plains. The southern seas progressively invaded North America around 95 million years ago, eventually connecting with the Arctic Ocean and constituting the second major submergence of the continent, leaving behind multi-colored clay layers averaging 2,000 feet in thickness that would later prove valuable for earthenware production.

The emergence of angiosperms from early Cretaceous seas approximately 90 million years ago represents one of the most significant botanical developments in earth's history, as these flowering plants rapidly proliferated across continental landmasses. Fig trees, magnolias, and tulip trees soon appeared, followed shortly by breadfruit trees and palms that spread throughout Europe and western North America. The closing of the Bering Strait 85 million years ago isolated the cooling northern waters, equalizing the previously divergent temperature conditions between Atlantic-Gulf waters and the Pacific Ocean, which had previously maintained distinct marine ecosystems due to their thermal variations. About 80 million years ago, substantial disruptions in earth's crust coincided with the deceleration of western continental drift, generating tremendous energy as the momentum of the continental mass caused extensive upheaval along the Pacific shores of North and South America, as well as initiating profound changes along Asia's Pacific coastlines. This circumpacific land elevation, culminating in present-day mountain ranges and extending over 25,000 miles, produced the most significant surface distortions since life's appearance on earth, accompanied by extensive aboveground and subterranean lava flows.

The conclusion of the great Cretaceous period coincides with the termination of major sea invasions of the continents, particularly North America, which had experienced twenty-four significant inundations throughout its geological history. While subsequent minor submergences occurred, none approached the extensive marine incursions characteristic of this and previous epochs. These alternating cycles of land and sea dominance operated on million-year intervals, reflecting a long-established rhythmic pattern in the elevation and depression of ocean floors and continental landmasses that continues through earth's history, albeit with diminishing frequency and magnitude. This period also marked the conclusion of continental drift and the establishment of modern mountain ranges, though the pressure of continental masses and their arrested momentum represent only partial factors in orogenesis; the fundamental determinant in mountain range location was the pre-existent lowland or trough that had accumulated the comparatively lighter deposits from land erosion and marine drift over preceding eras.

These lighter areas of land accumulation, sometimes reaching thicknesses of 15,000 to 20,000 feet, exhibited greater susceptibility to buckling and elevation when subjected to crustal pressures, becoming the initial regions to fold and rise in response to competing forces and pressures within and beneath the earth's crust. While some landmasses rose without folding, the formation of the Rocky Mountains involved extensive folding and tilting of strata coupled with massive overthrusts of various rock layers both underground and at the surface. The planet's mountain ranges exhibit a chronological distribution, with the oldest formations located in Asia, Greenland, and northern Europe among ancient east-west systems, while mid-age mountains comprise the circumpacific group and Europe's second east-west system, which spans nearly 10,000 miles from Europe into the West Indies elevations. The geologically recent Rocky Mountain system experienced multiple cycles of elevation and submergence before the formation of its present configuration, with peaks like Pikes Peak and Longs Peak representing outstanding examples of multi-generational mountain development, having maintained their elevation above sea level through several inundation periods.

The Cretaceous age witnessed significant biological transformations alongside its geological developments, with sea urchins flourishing while corals and crinoids declined, and ammonites—previously a dominant marine species—experiencing rapid diminution. Terrestrial ecosystems underwent equally dramatic changes as fern forests yielded to pine and other modern tree species, including the massive redwoods. Though placental mammals had not yet evolved by the period's conclusion, the biological foundations had been established for the subsequent emergence of mammalian ancestors. This fifty-million-year Cretaceous period brought to a close the premammalian era of terrestrial life, the hundred-million-year Mesozoic epoch, extending from the initial appearance of land organisms to the threshold of the evolutionary lineage that would eventually produce human beings and related species.