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Updated: June 23, 2025
Again, vast as is the number of undoubtedly Ganoid fossil Fishes, and great as is their range in time, a large mass of evidence has recently been adduced to show that almost all those respecting which we possess sufficient information, are referable to the same sub-ordinal groups as the existing Lepidosteus, Polypterus, and Sturgeon; and that a singular relation obtains between the older and the younger Fishes; the former, the Devonian Ganoids, being almost all members of the same sub-order as Polypterus, while the Mesozoic Ganoids are almost all similarly allied to Lepidosteus.
Analogy seems to me to be rather in favour of, than against, the supposition that while only Ganoid fishes inhabited the fresh waters of our Devonian land, Amphibia and Reptilia, or even higher forms, may have existed, though we have not yet found them.
And this is the plain story of that marvellous discovery of a 'missing link' in our own pedigree. In the oldest secondary rocks of Britain and elsewhere there occur in abundance the teeth of a genus of ganoid fishes known as the Ceratodi.
Seeking some impersonal point for measure, he turned to see what had happened to his oldest friend and cousin the ganoid fish, the Pteraspis of Ludlow and Wenlock, with whom he had sported when geological life was young; as though they had all remained together in time to act the Mask of Comus at Ludlow Castle, and repeat "how charming is divine philosophy!"
The head was larger than an ordinary horse's head would be. The body was lightly built. Each of its tiny feet had three toes. Gail watched Soames' face. "You see? How about this?" The ornament of the other necklace was a tiny metal fish. It had fins and a tail, but no scales. Instead, its body was protected by bony armor. It was a ganoid fish, like a sturgeon.
Krefft took away the breath of scientific Europe by informing it that he had found the extinct ganoid swimming about as large as life, and six feet long, without the faintest consciousness of its own scientific importance, in a river in Queensland at the present day.
But it was not a sturgeon, though sturgeons are now the main representatives of what once were innumerable ganoid species. Soames shook his head, then spoke to Gail and Captain Moggs. "The ship was built for children to operate, I can't imagine why. But there's nothing like a weapon in view. I'm going to call Base before they get alarmed."
And it is in fresh water that we find seven genera of Ganoid fishes, remnants of a once preponderant order: and in fresh water we find some of the most anomalous forms now known in the world, as the Ornithorhynchus and Lepidosiren, which, like fossils, connect to a certain extent orders now widely separated in the natural scale.
Again, vast as is the number of undoubtedly Ganoid fossil Fishes, and great as is their range in time, a large mass of evidence has recently been adduced to show that almost all those respecting which we possess sufficient information, are referable to the same sub-ordinal groups as the existing 'Lepidosteus', 'Polypterus', and Sturgeon; and that a singular relation obtains between the older and the younger Fishes; the former, the Devonian Ganoids, being almost all members of the same sub-order as 'Polypterus', while the Mesozoic Ganoids are almost all similarly allied to 'Lepidosteus'.
In the embryo of the cod or perch the backbone has, at an early stage, the same position as in the shark or ganoid; only at a later stage does it attain its definite position. The embryology of turtles throws light upon the fossil chelonians. It is already known that the embryonic changes of frogs and toads coincide with what is known of their succession in past ages.
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