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Difficulty: MediumEvidence for Evolution: Comparative Anatomy, Embryology, and Vestigial Organs

During early embryonic development, baleen whales temporarily form tooth buds that are completely reabsorbed before birth and never become functional teeth in adults. What evolutionary conclusion can be drawn from the presence of these transient structures?

  1. Baleen whales evolved from ancestral organisms that possessed functional teeth.Answer
  2. B
    Tooth buds are analogous structures that adapted for filter feeding during fetal stages.
  3. C
    The tooth buds represent convergent evolution resulting from shared marine selection pressures.
  4. D
    The tooth buds are acquired somatic traits that atrophy due to lack of disuse during gestation.

Answer

The presence of temporary tooth buds in baleen whale embryos indicates that baleen whales evolved from ancestral organisms that possessed functional teeth.
The correct answer correctly identifies that transient embryonic structures, such as tooth buds in baleen whales, are vestigial developmental features. They persist in early embryos because evolutionary modification often alters later developmental stages while preserving early ancestral genetic blueprints. This provides direct embryological evidence that modern baleen whales share a common ancestor with toothed whales.

Step-by-Step Solution

1
Analyze the nature of the anatomical structure described in the stem.
The structure is a transient, non-functional embryonic feature (vestigial embryonic trait).
Structures present during embryonic development but reabsorbed before birth reflect genetic history rather than current functional adaptation.
2
Relate embryological features to evolutionary evidence.
Embryos often exhibit ancestral traits because the genetic pathways controlling early development are conserved from common ancestors.
Organisms retain developmental blueprints from their lineage, providing strong evidence of evolutionary descent.

Key Concept

Comparative Embryology and Vestigial Traits as Evidence for Evolution
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Topics

Evidence for Evolution: Comparative Anatomy, Embryology, and Vestigial Organs

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