Vertebrates, the animals with backbones, first appeared on the Earth during the Palaeozoic period. Agnathids were the oldest vertebrates which resembled fish. Rocks from late Palaeozoic period revealed 75 different species of amphibians. Most of the fossils resembled today’s salamanders. Body, cast and trace fossils of dinosaurs have been found during exploration. Fossils of the huge woolly mammoths that existed in Cenozoic era are also found. One such entirely preserved fossil of a mammoth was found in Alaska.
Fossil Animals: Vertebrates
