GLORIES OF THE FROG’S GREAT ANCESTORS

MODERN amphibia, the frogs, toads, newts and so on, do not make a very impressive show in the pageant of living things; no living amphibian approaches in size or interest the rather diverse forms of the Carboniferous and Permian times. The first forms must have lived along with their not so distant fishy relatives in the rivers and ponds, occasionally venturing on the muddy banks, but having of necessity to return to the water in the breeding season.

In the beginning they were not so unlike the fish in feeding habits and in sense organisation, but they were probably less able to defend themselves from attack and so had to leave the water for the land. On the other hand, from the safety of the shores, they could snatch a plenteous food supply from their contemporaries swimming in the water or stranded in the mud of drying pools. In size, in habit, and in general appear-

ance some of these amphibians were not unlike crocodiles.

We have the evidence of bones from the Permian period 1 found in Texas, that some amphibians (such as Cacops) were to all intents and purposes terrestrial, having to return to the water only to lay eggs. Though this particular animal (the Cacops) was only about two feet long, others of a similar kind grew to five and six feet.

By this time the amphibians had lost one of their five fingers, the hands having now only four of them well developed. Some forms, too, had developed a certain amount of armour on their backs as a protection against flesh-eating contemporaries. While most of the amphibians were probably still flesh-eaters at this time (the Permian period), it is possible that some may have eaten insects, which we know to have been plentiful, while yet others may have become vegetarians. The amphibians can hardly have been beautiful creatures. With their large triangular skulls, broad and low bodies, and sprawling limbs stuck well out from the body, they must have walked slowly and awkwardly over the land.

THE AMPHIBIANS’ STRATEGY TO PRESERVE THEIR RACE HAPPILY placed in some circumstances, they were not however free from troubles. The reptiles were now beginning to roam the land and harass their amphibian progenitors, and they were a more advanced type without the amphibian limitations. To avoid this new complication, some of the amphibians delayed their water-living and gill-breathing larval state (like the modern axolotl) and eventually became entirely water-living. Indeed we have evidence that some were actually marine, which seems strange if we remember how deadly the salt waters are to the larval forms of the modern amphibian. These secondarily aquatic and degenerate amphibians are common in the Triassic deposits of Germany, where remains of the large Mastodonsaurus, whose skull was four feet long, and the smaller but well-known Capitosaurns have been found. These forms are often grouped together under the name of Labyrinthodonts (‘labyrinth-toothed ‘), a name which has reference to the remarkable pleating of the wall of the conical and hollow teeth. The marine kinds were long and narrow-headed, and are known from deposits in Spitsbergen.

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