Which group of animals is characterized by having scales and laying shelled eggs?

Reptilia, or reptiles, are a group of animals that are characterized by several distinctive features, including having scales covering their bodies and the ability to lay shelled eggs. The scales serve as a protective barrier and help prevent water loss, which is critical for survival in various environments, particularly terrestrial habitats.

Reptiles typically reproduce through the laying of eggs that have a hard or leathery shell; this adaptation is beneficial as it provides protection for the developing embryos from the external environment and allows for reproduction away from water bodies. This reproductive strategy distinguishes them from other groups like Amphibia, which usually require water for laying their eggs, and Mammalia, where most species give live birth and do not lay eggs (with the exception of monotremes).

In contrast, Aves (birds) also have feathers and lay eggs, but their egg structure and the presence of feathers differentiate them significantly from reptiles. Thus, the key aspects of scale coverage and shelled eggs distinctly point to reptiles as the correct answer.