What is the first known member of the great group of backboned animals at whose head man has placed himself?
We human beings, and our four-footed cousins, all backboned animals in fact, do not manage in any of these ways.
With the exception of the great class of Birds, the Bats are the only surviving backboned animals that possess the organs of true flight.
For the purposes of the present work it is unnecessary to enter minutely into all the characters that distinguish the Mammals from the other backboned animals.
There are still two small groups of backboned animals to be described, representing the classes Reptilia and Batrachia.
The backboned animals are the highest of all the animal kingdom.
Still, on the whole, the backboned animals are the highest and as you and I both belong to that class we could never afford to confess to any doubts as to their superiority.
And the lowest of all backboned animals we call fishes.
Nowhere in living nature or in the rocks was any intermediate type known between the backboned and the non-backboned animal.
His researches, especially among vertebrates, or backboned animals, revealed an altogether undreamed-of wealth of entombed remains.
Silurian times; or a skeleton, such as all the backboned (vertebrate) animals possess.
This resemblance shows itself in the pelvis, or bony arch with which the hind limbs are connected in vertebrate or backboned animals, and in the limbs themselves.
And homologies, less close but equally unmistakable, connect all backboned animals one with another; and the lowest backboned types are closely joined to worm-like forms not usually classed as vertebrates.
There is no reason why the name mammal should not be commonly used, just as birds, reptiles, amphibians, and fishes are used for the other groups of backboned animals.
In this brief study we shall not go into much detail about invertebrates, but with the backboned animals or vertebrates we shall go a little further.
For example, some creatures are on the border-land between plants and animals, and again some animals are between the backboned animals and those without backbones.
My children had learnt something about the two great divisions of animals, those which belong to the great Backboned Family and those which have no backbone.
Those which possess this structure are known as Vertebrata, or backboned animals, because the vertebral-column or backbone is always present.
Now a cat is a vertebrate or backboned animal, possessing four limbs, and if we had to describe its parts roughly, we should specify the head, trunk, limbs and tail.
We know, too, that all the backboned animals, some of them very unlike dogs, are believed to be related to each other, but of the thousands of these animals and of their relationships our knowledge is scanty.
When perfectly dry, sections may be cut through them in various places with a sharp knife, and by this means a very good idea of the simple lung structure of the lower backboned animals can be obtained.
Hence these five backboned classes may be brought together into a higher group called a branch or phylum.
It thrills the imagination to learn that this is the only supporting axis that the lower orders of the backboned race possess.
Bearing this law in mind, let us take a survey of the emergence of mind among backboned animals.
In another part of this book there is an account of the dawn of mind in backboned animals; what we aim at here is an outline of what may be called the inclined plane of animal behaviour.
But it was in this period that the first backboned animals made their appearance--an epoch-making step in evolution.
The notochord is the supporting axis of the pioneer backboned animals, namely the Lancelets and the Round-mouths (Cyclostomes), such as the Lamprey.
The rock-record, which cannot be wrong, though we may read it wrongly, shows clearly that there was once a time in the history of the Earth when the only backboned animals were Fishes.
That is to say, there was an emergence of backboned animals which were free from water and relinquished the method of breathing by gills, which Amphibians retained in their young stages at least.
But how many of you have any idea that these same 'squirts' really belong to the great division of vertebrates or backboned animals?
But though so different in their adult stages, they all begin life as vertebrated or backboned animals, though in some this stage is more perfect than in others.
The description applies only to the backboned vertebrates, and not to nearly all of them.
Many of the lower backboned animals probably grow during the whole of life, but those which suckle their young generally cease growing after a fraction (in us from one-fourth to one-fifth) of the allotted span of life is past.
When we come to the backboned animals there is a little more tendency to a stationary location.
With the exception of the backboned animals, every important branch of the animal kingdom is represented, and it is just possible that we have even earlier forms of the vertebrates themselves.
Now the backboned animals first make their clear and unmistakable appearance.
Altogether a higher state of reproduction is encountered when we reach the reptiles, which are the next higher class of backboned animals.
In order that we may the more clearly understand how the mammals produce their young and nourish them, we shall begin at the lowest class of the backboned animals and note how the process is there accomplished.
This period is called the age of invertebrates because, although there is an enormous wealth of animal and plant life in the Silurian, there are no backboned animals except the lowest kinds of fishes.
I have said that the foot first appeared when the backboned creatures came out of the waters to live upon the dry land.
So far the examples have been taken from one order of the highest class of backboned animals, called mammalia.
The birds are another class of backboned animals which exhibit identical principles of relationship.
For the reasons specified, the backboned animals provide the richest arrays of these series, and such histories as those of horses and elephants have taken their places in zoölogical science as classics.
The brief review of backboned animals has shown how comprehensive are the principles of relationship.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "backboned" in a variety of sentences. We hope that you will now be able to make sentences using this word.
