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Skates and rays of a more or less modern type, and ancestral gar-pikes and sturgeons, enter the arena. Their superiority in organisation soon makes itself felt, and they enter upon the rapid evolution which will, by the next period, give them the first place in the fish world. Over the whole Mesozoic world, therefore, we find advance and the promise of greater advance.
The Pterodactyles, which preceded the class of birds, and the Ichthyosauri, which preceded the Cetacea, are other examples of such prophetic types." Now, these reptile-like fishes, of which gar-pikes are the living representatives, though of earlier appearance, are admittedly of higher rank than common fishes. And so, perhaps, of the other prophetic types. Here type and antitype correspond.
Of these two groups one consists chiefly now of the Gar-Pikes of our Western waters, though the Sturgeons share also in some of their features. In these fishes there is a singular union of reptilian with fish-like characters.
These fishes, which preceded the appearance of reptiles, present a combination of ichthyic and reptilian characters not to be found in the true members of this class, which form its bulk at present. Now these reptile-like fishes, of which gar-pikes are the living representatives, though of earlier appearance, are admittedly of higher rank than common fishes.
A large proportion of them were no doubt Ganoids; for they had the same peculiar articulation of the vertebrae, the flexibility of the neck, and the hard scales so characteristic of our Gar-Pikes. There is another type of these ancient Vertebrates, which has also its representatives among our modern fishes.
Then it was noticed that our common fish formed a fairly well-defined group, but that the ganoids, including the sturgeons, gar-pikes, and some others, had at least traces of amphibian characteristics. Such generalized forms, with the characteristics of the class less sharply marked, were usually by common consent placed at the bottom of the class.
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