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What is the Geologic Time Scale?

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The Geologic Time Scale is a system used by geologists and paleontologists to describe the timing and relationships of events in Earth's history, divided into eons, eras, periods, epochs, and ages.

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What are Saurischian dinosaurs?

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Saurischian dinosaurs are a group of dinosaurs characterized by their lizard-like hips, which include theropods (like birds) and sauropodomorphs.

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What are Ornithischian dinosaurs?

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Ornithischian dinosaurs are a group of dinosaurs with bird-like hips, known for being primarily herbivorous and including species like Stegosaurus and Triceratops.

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What is a cladogram?

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A cladogram is a diagram that shows the evolutionary relationships among a group of organisms, illustrating how species are related through common ancestors.

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What does a node on a cladogram represent?

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A node on a cladogram represents the last point at which two groups shared a common ancestor.

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What is a phylogenetic tree?

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A phylogenetic tree is a diagram that represents the evolutionary relationships among a group of organisms, showing how they have diverged from common ancestors.

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What does a branch in a phylogenetic tree represent?

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A branch in a phylogenetic tree represents a common ancestor and the divergence of species over time.

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What is the significance of fossils in understanding geologic time?

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Fossils provide evidence of past life and help scientists understand the evolution of organisms and the timing of their existence in the geologic time scale.

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What is the principle of superposition in geology?

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The principle of superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

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What is a common ancestor?

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A common ancestor is an ancestral species from which two or more species have evolved.