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Updated: June 27, 2025
The ancestors of our race during this period were at first represented by true fishes, then by dipneusts and amphibia, and finally by the earliest Amniotes, or the Protamniotes. The third chief section of the organic history of the earth is the Mesozoic or Secondary period. This again is subdivided into three divisions Triassic, Jurassic, and Cretaceous.
From New Jersey southward the earliest Tertiary sands and clays, still unconsolidated, leave only a narrow strip of the edge of the Cretaceous between them and the Triassic and crystalline rocks of the Piedmont oldland; hence the Atlantic shore here stood farther in than now, and at the beginning of the period the present coastal plain was continental delta.
These fishes have organs as complex and perfect as the fishes of to-day. Suddenly, in the "carbonic age" amphibia and reptiles appear, and then come, in the "Triassic" the huge reptiles known as dinosaurs. "We seek in vain for the progenitors of these highly organized articulates or for some conceivable method by which their wings and special breathing apparatus could have evolved.
I found them maintaining their erect attitude, at points many miles apart, in beds both above and between the seams of coal. In order to explain this fact, we must suppose such shales and sandstones to have been gradually accumulated during the slow and repeated subsidence of the whole region. Triassic coal-shale, Richmond, Virginia. a. Estheria ovata. b. Young of same. c. Natural size of a. d.
I confess this is wholly incredible to me. The Permian and the Triassic deposits pass completely into one another; there is no sort of discontinuity answering to an unrecorded "Antetrias"; and, what is more, we have evidence of immensely extensive dry land during the formation of these deposits.
We observe, for example, in the Triassic, Oolitic, and Cretaceous strata, not only an absence of placental mammalia, but the presence of innumerable reptiles, some of large size, terrestrial and aquatic, herbivorous and predaceous, fitted to perform the functions now discharged by the mammalia.
Dolomitic conglomerate. Near Bristol, in Somersetshire, and in other counties bordering the Severn, the lowest strata belonging to the Triassic series consist of a conglomerate or breccia resting unconformably upon the Old Red Sandstone, and on different members of the Carboniferous rocks, such as the Coal Measures, Millstone Grit, and Mountain Limestone.
If, as there is great reason to believe, true Birds existed in the Triassic epoch, the ornithoscelidous forms by which Reptiles passed into Birds must have preceded them. In fact there is, even at present, considerable ground for suspecting the existence of Dinosauria in the Permian formations; but, in that case, lizards must be of still earlier date.
Starting from the high plateau of Utah, and going south toward the canon, we descend a grand geologic stairway, every shelf or tread of which consists of different formations fifty or more miles broad, from the Eocene, at an altitude of over ten thousand feet at the start, across the Cretaceous, the Jurassic, the Triassic, the Permian, to the Carboniferous, which is the bottom or landing of the Grand Canon plateau at an altitude of about five thousand feet.
Is it conceivable that these last should really represent the whole terrestrial population of that time, and that the development of Mammals, of Birds, and of the highest forms of Reptiles, should have been crowded into the time during which the Permian conditions quietly passed away, and the Triassic conditions began?
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