Answer:
1. amphibians
2. Carboniferous
3. For glaciation to begin, something needs to cause Earth's temperatures to drop. If this happens, snow that falls on the polar ice caps doesn't melt, and glaciers grow. As snow and ice reflect sunlight, the Earth's temperature is reduced even further, causing glaciers to continue growing.
4. Sea level changes cause marine transgressions and regressions. During a marine transgression, the shoreline moves inland, leaving sedimentary deposits that contain fossils. The shoreline retreats during a marine regression, leaving behind the deposited sediments
Explanation:
The first four-legged animals to reach land were Ichthyostega about 360 million years ago which is amphibians. This organism has skeletal features just like fish but also had sturdy shoulders, hips and capable of supporting the body's weight on land.
Pangaea was fully formed during the late Permian Period. Pangea existed between 299 million years ago at the start of the Permian Period of geological time to 180 million years ago during the Jurassic Period. It remained in its fully assembled state for about 100 million years before it began to break into continents.
Glaciers begin to form when snow remains on the surface of earth in the same area where enough snow accumulates which transform into ice. Each year, new layers of snow formed and compress the previous layers which leads to glaciation.
Changes in sea level and evidence of past marine life are related because fossils of marine organisms are found on these lands which tells us that once in this region there was a sea. Changes in sea level are caused by tectonic uplift and subsidence.
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