Question

One of the following is not a trait of prototherians.

• A. Egg laying
• B. Absence of teats over mammary glands
• C. Absence of corpus callosum
• D. Presence of testes outside the abdominal cavity

Answer 1

The correct option is D Presence of testes outside the abdominal cavity

Prototherians are egg-laying mammal. They retain many characters from their ancestor such as laying eggs rather than giving birth to young ones, having one opening for excretion and urination etc. These organisms have mammalian traits also such as fur on the body, four chambered heart, three middle ear bones, ability to lactate and single jaw bone. In these organisms external testes are absent.

So the correct option is 'Presence of testes outside the abdominal cavity'.