What is the status of duck-billed platypus in the evolutionary lineage?

Explanation

**Step-by-Step Solution:**

1. **Definition of Duck-Billed Platypus**: The duck-billed platypus is a unique mammal known for its distinctive features, including a duck-like bill and webbed feet. It is classified as an egg-laying mammal, which sets it apart from most other mammals.

2. **Oviparous vs. Viviparous**: The duck-billed platypus is oviparous, meaning it lays eggs rather than giving birth to live young (viviparous). This characteristic is significant in understanding its evolutionary status.

3. **Evolutionary Transition**: The duck-billed platypus represents a transitional form in the evolutionary lineage. It showcases the evolutionary shift from ancestral reptiles to modern placental mammals. This indicates that it retains some primitive traits while also possessing features typical of mammals.

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