Identify the periods marked a, b, c and d in the given diagram showing evolution of vertebrates.
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a - Triassic, b - Carboniferous, c - Tertiary and d - Cretaceous
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a - Tertiary, b - Triassic, c - Cretaceous and d - Carboniferous
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a - Triassic, b - Carboniferous, c - Cretaceous and d - Tertiary
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a - Carboniferous, b - Triassic, c - Cretaceous and d - Tertiary
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a - Cretaceous, b - Triassic, c - Carboniferous and d - Tertiary
In the diagram a-Carboniferous, b-Triassic, c-Cretaceous and d- Tertiary. Therefore, the given option is correct.
In the standard geological timeline used for vertebrate evolution diagrams, the Carboniferous period comes first (when amphibians diversified), followed by the Triassic (early dinosaurs and first mammals), then the Cretaceous (peak of dinosaurs), and finally the Tertiary (rise of mammals after the dinosaur extinction). Matching this chronological order to the labels a, b, c, and d gives Carboniferous, Triassic, Cretaceous, and Tertiary respectively.