In what form the terrestrial reptiles excrete their nitrogenous wastes? How is this kind of excretion advantageous to terrestrial vertebrates which lay shelled eggs?

Explanation

### Step-by-Step Solution:

1. **Identification of Nitrogenous Waste in Terrestrial Reptiles**:
Terrestrial reptiles excrete their nitrogenous waste primarily in the form of uric acid.

2. **Transformation Process**:
In their bodies, nitrogenous waste begins as ammonia, which is a more toxic form. This ammonia undergoes a transformation process to convert it into uric acid, which is less toxic and more suitable for excretion.

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