The Devonian, Carboniferous and Permian Periods

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The Devonian, Carboniferous and Permian Periods

 

The Devonian, Carboniferous and Permian periods are collectively termed the upper Palaeozoic era. At this time in Earth’s history, the scattered landmasses of the world were moving towards each other. As they collided, mountain ranges arose along the leading edges. These mountain ranges rapidly eroded, with the sand and rubble spreading out in the surrounding shallow deltas and swamps. Moist lowlands became colonized by plants. This is where the first vertebrates set foot on land.(walking dinosaur costume)

 

THE EARLIEST TETRAPODS

The term “tetrapod”  refers to all vertebrates excluding what we would call the fish. The word literally means “four-footed” However, the classification also covers things like birds that only have two feet, and whales ami snakes that have none. The main point is that they are all descended from four-footed ancestors, atui the remains of these are to be found in Devonian and Carboniferous rocks.

 

Ichthyostega

This is the classic animal that shows transitional features between those of a fish and an amphibian. The skull is very fish-like and the tail carries a swimming fin.

However, the legs are those of a tetrapod, but seemingly evolved for swimming and pushing through aquatic plants in shallow water.(animatronic dinosaur)

Features: The skull is very much like that of a fish. The backbone is stronger than that of the most closely related fish, and the rib­cage is a strong structure of overlapping ribs – all weight­bearing features. The legs are built very much like those of every other tetrapod, with a single upper bone (a humerus in the front legs and a femur in the rear) and two lower bones (the radius and ulna, and the tibia and fibula). The hind limbs are smaller thanthe forelimbs andacted as paddles. The hind foot has seven toes. The ears appear to have been adapted to work primarily underwater.