They are present in highly modified forms in the very oldest palæozoic strata, and probably therefore came into existence as the first traces of continental areas were beginning to rise above the primeval ocean.
In the PalA|ozoic this consideration sinks in importance.
The Foraminifera of the PalA|ozoic we have noticed in the last chapter; but we now find a new type of ProtozoanaEuro"that of the Sponge.
This recurred at the close of the Devonian and in the time of the Lower Carboniferous limestone; and finally the PalA|ozoic flora disappeared altogether in the Permian, to be replaced by new types in the Mesozoic.
What it may be in the future, we can perhaps as little guess as an intelligence studying the PalA|ozoic world could have understood that of the present time.
Certain it is, that according to present appearances we have a new beginning in the Cambrian, which introduces the great PalA|ozoic age, and few links of connection are known between this and the previous Eozoic.
A remarkable picture of the conditions of PalA|ozoic land life is presented by the occurrence of remains of reptiles, millepedes and land-snails in such erect trees as that represented in Fig.
This type of animal, entering on the stage in full force in the Older Cambrian, continues under many forms through the whole PalA|ozoic age, dying out finally in the Carboniferous.
We have said something of what was in the PalA|ozoic flora; but what of that which was not?
EurooeWe find that the large number of genera made their first appearance during the PalA|ozoic periods, and since they have been decreasing in number to the present period.
Taking all things into consideration, it is, I think, obvious that the average rate of denudation since the beginning of Palæozoic times was probably not much greater than at the present day.
The rate of rotation has been slowly decreasing for ages, and in Palæozoic times it must, of course, have been greater than at present.
We have no geological grounds to conclude that the winds of Palæozoic times were stronger than those at the present day.
The next period of the Palæozoic is known as the Devonian age, or the age of fishes.
Hence it is a serious matter to attempt to describe the climate of any part of the Palæozoic era.
The ancestors of these king crabs were the finest and best developed animals in this early Palæozoic time.
Describe the life of each of the three periods of the Palæozoic era.
Looking backwards over the many millions of years comprised in the Palæozoic era, what may we emphasise as the most salient features?
ARCHÆOZOIC AGES Living creatures began to be upon the earth.
The Establishment of Invertebrate Stocks It is an astounding fact that at least half of geological time (the Archæozoic and Proterozoic eras) passed before there were living creatures with parts sufficiently hard to form fossils.
They died away entirely with the end of the Palæozoic era.
Between the Palæozoic and Neozoic periods of Professor Forbes, there is scarcely a species in common, and the greater part of the genera and families also disappear to be replaced by new ones.
Turning to the Vertebrata, the only palæozoic Elasmobranch Fish of which we have any complete knowledge is the Devonian and Carboniferous Pleuracanthus, which differs no more from existing Sharks than these do from one another.
Geographical provinces and zones may have been as distinctly marked in the Palæozoic epoch as at present, and those seemingly sudden appearances of new genera and species, which we ascribe to new creation, may be simple results of migration.
So, none of the Palæozoic Sharks have shown themselves to be possessed of ossified vertebræ, while the majority of modern Sharks possess such vertebræ.
This divergence is the most marked in the Palæozoic forms of life, less so in those of the Mesozoic period, and less still in the Tertiary period.
The latter genus is nearly allied to the Archoeocidaris of the Carboniferous, so that this Permian form belongs to a characteristically Palæozoic type.
From the foregoing it will be gathered that one of the most important points in connection with the Triassic Mollusca is the remarkable intermixture of Palæozoic and Mesozoic types which they exhibit.
Palæozoic type of the Brachiopods, which is destined to undergo a vast extension in later ages.
The Lamp-shells (Brachiopods) have now reached a further stage of the progressive decline, which they have been undergoing ever since the close of the Palæozoic period.
A Palæozoic genus of Sea-urchins, related to the existing Cidaris.
The limestone is probably of older Palæozoic age (?
Their structure is at any rate palpably different, and they bear no such resemblance to the pores of the human skin as that which the Palæozoic pores present.
But did any of them ever tell a story half so instructive or so strange as that told by the incalculably more ancient ganoid tiles of the Palæozoic and Secondary periods?
What, asks the reader, was the character of the ancient denizen of the Palæozoic basin of which it had formed a part?
They lie about five miles south of Elgin, not far distant from where the palæozoic deposits of the coast-side lean against the great primary nucleus of the interior.
The united thickness of these three great series may possibly far surpass that of all the succeeding rocks from the base of the Palæozoic series to the present time.
When palæozoic land-plants have been converted into graphite, they sometimes perfectly retain their structure.
The same phenomena may be observed in joints of Crinoids from the Palæozoic rocks, and they constitute proofs of organic origin even more irrefragable than the filling with serpentine.
I have for some time made the minute structure of Palæozoic limestones a special study, and have described some of them from the Silurian formations of Canada.
The mode of filling thus suggested for the chambers and tubes of Eozoon, is precisely that which takes place in modern Foraminifera filled with glauconite, and in Palæozoic crinoids and corals filled with other hydrous silicates.
General Section, showing the Relations of the Laurentian and Palæozoic Rocks in Canada.
Murchison, in the year 1841, for certain deposits which are now known to terminate upwards the great primeval or Palæozoic Series.
Part, at least, of this oldest of the Secondary rocks was formed of the material of the older Palæozoic strata, that had then risen above the surface of the water.
Schlotheimii is widely disseminated both in England, Germany, and Russia, with Lingula Credneri, and other Palæozoic Brachiopoda.
In the Later Palæozoic Period that visitant might have been equally sure that life could not go beyond the edge of a swamp.
As we ascend the higher levels of the Later Palæozoic record, we find the process of air adaptation has gone as far as the appearance of true reptiles amidst the abundant and various amphibia.
There are first the Upper Palæozoic Rocks, and above these the geologists distinguish two great divisions.
Such a propitious conjunction it must have been that gave the age of luxuriant low-grade growth of the coal-measures; such an adverse series of circumstances that chilled the closing æons of the Palæozoic time.
Illustration: Some Oligocene Mammals] From the appearance of the vertebrated animals in the Lower Palæozoic Age, when the fish first swarmed out into the sea, there has been a steady progressive development of vertebrated creatures.
Such was the life of the shallow seas through a hundred million years or more in the early Palæozoic period.
That is as true of all the minute creatures that swarmed and reproduced and died in the Archæozoic and Proterozoic seas, as it is of men to-day.
Before the seaweeds could creep up out of the Early Palæozoic seas into the intertidal line of the beach, they had to develop a tougher outer skin to hold their moisture.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "ozoic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
