how do the presences of fossils in both south america and africa provide evidence in support of continental drift
The presence of fossils in both South America and Africa provides evidence in support of continental drift through paleontological and biostratigraphic correlation. Here's how it works:
1. Similarity of Fossil Assemblages: Fossils of plants and animals found in South America and Africa display remarkable similarities, suggesting a shared history and connection between the two continents. For example, fossils of the ancient freshwater reptile Mesosaurus are found in both South America and Africa. This indicates that these regions were once connected and that the reptile could not have swum across vast oceans.
2. Matching Geological Formations: The presence of matching geological formations across South America and Africa further supports continental drift. For instance, the rock formations and mountains in the eastern coast of Brazil align with the ones in the western coast of Africa when the continents are reconstructed to their original positions. This implies that these regions were part of a continuous landmass.
3. Fossil Distribution Patterns: Some fossil groups have restricted geographical distributions, meaning they were confined to specific areas due to environmental factors. By studying the distribution patterns of these fossils, it becomes evident that they could not have moved independently across vast oceans. For instance, the Glossopteris flora, an ancient plant group, has been found in South America, Africa, Australia, India, and Antarctica. The presence of this flora across multiple continents indicates that these regions were once connected as part of a supercontinent called Gondwana.
4. Paleoclimatic Evidence: Fossils also provide evidence of past climates, and the presence of fossils of tropical or warm climate organisms in regions that are currently cold indicates significant changes in the Earth's climatic conditions over time. This change in climate can be better explained by continental drift, as the movement of landmasses can cause dramatic changes in atmospheric and oceanic circulation patterns.
By considering all these pieces of evidence together, scientists have been able to reconstruct the ancient positions of South America and Africa and propose the theory of continental drift, which eventually led to the development of the theory of plate tectonics.