Learn on PengiAmplify Science (California) Grade 8Chapter 3: Identifying Related Species

Lesson 3: Classifying the Mystery Fossil

Key Idea.

Section 1

Solving the Mystery

Key Idea

We can finally classify the Maiacetus fossil.

Although it has legs like a wolf, its skeleton tells a different story. It possesses the unique "involucrum" (a thick ear bone). This structure is diagnostic—it is found only in whales.

Section 2

The Transitional Form

Key Idea

The evidence tells a clear evolutionary story:

  1. Shared Structure: The ear bone proves it belongs to the whale lineage.
  2. Different Feature: The legs prove it lived early in history, before whales lost their limbs.

Lesson overview

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Section 1

Solving the Mystery

Key Idea

We can finally classify the Maiacetus fossil.

Although it has legs like a wolf, its skeleton tells a different story. It possesses the unique "involucrum" (a thick ear bone). This structure is diagnostic—it is found only in whales.

Section 2

The Transitional Form

Key Idea

The evidence tells a clear evolutionary story:

  1. Shared Structure: The ear bone proves it belongs to the whale lineage.
  2. Different Feature: The legs prove it lived early in history, before whales lost their limbs.