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And, in speculating upon the origin of a given group, he rarely goes further back than the "Ante-period," which precedes that in which the remains of animals belonging to that group are found. Thus, as fossil remains of the majority of the groups of Reptilia are first found in the Trias, they are assumed to have originated in the "Antetriassic" period, or between the Permian and Triassic epochs.
Cassian, now generally assigned to the lowest members of the Upper Trias or Keuper, leads us to suspect that when the strata of the Triassic age are better known, especially those belonging to the period of the Bunter sandstone, the break between the Palaeozoic and Mesozoic Periods may be almost effaced. Indeed some geologists are not yet satisfied that the true position of the St.
Cruz de Malabón, Perez Dasmariñias and other towns, before the Worthy Chief Mariano Trías, who ultimately refused, with dignity, the high position of Secretary of War, for which rank he was promoted for reasons which are not worth publishing here.
They may be classed in three divisions, the FLESH-EATING DINOSAURS, the REPTILE-FOOTED DINOSAURS, and the BEAKED DINOSAURS, the latter two divisions being herbivorous. This group was the longest-lived of any of the three, beginning in the Trias and continuing to the close of the Mesozoic era.
In Cheshire and Lancashire there are red clays containing gypsum and salt of the age of the Trias which are between 1000 and 1500 feet thick. In some places lenticular masses of pure rock-salt nearly 100 feet thick are interpolated between the argillaceous beds.
And, in speculating upon the origin of a given group, he rarely goes further back than the "Ante-period," which precedes that in which the remains of animals belonging to that group are found. Thus, as fossil remains of the majority of the groups of Reptilia are first found in the Trias, they are assumed to have originated in the "Antetriassic" period, or between the Permian and Triassic epochs.
And, knowing that reptiles that walked upon their hind legs and shared many of the anatomical characters of birds did once exist, it becomes a very important question whether the tracks in the Trias of Massachusetts, to which I referred some time ago, and which formerly used to be unhesitatingly ascribed to birds, may not all have been made by Ornithoscelidan reptiles; and whether, if we could obtain the skeletons of the animals which made these tracks, we should not find in them the actual steps of the evolutional process by which reptiles gave rise to birds.
The hotter the summer, the more ice is found in the Eiskammer, and the general belief is that it all disappears in winter. The cave proper, which assumes stupendous dimensions in its long course, shows no ice. It seems to be formed in the Muschelkalk of the Trias formation, and so far no limestone stalactites have been discovered. It has not, however, as yet been fully explored.
The new fauna was, as might have been expected, in part peculiar, not a few of the species of Mollusca being referable to new genera; while some species were common to the older, and some to the newer rocks. On the whole, the new forms have helped greatly to lessen the discordance, not only between the Lias and Trias, but also generally between Palaeozoic and Mesozoic formations.
But if this be the case, how much further back must we go to find the common stock of the monodelphous Mammalia? As to the Didelphia, if we may trust the evidence which seems to be afforded by their very scanty remains, a Hypsiprymnoid form existed at the epoch of the Trias, contemporaneously with a Carnivorous form.
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