Final answer:
Evolution in mammal's chewing structures and mechanics led to the development of specialized teeth and jaw muscles, and facilitated the evolution of the mammalian inner ear with three tiny bones for improved hearing. The correct choice relating to these adaptations is option D, improved inner ear.
Step-by-step explanation:
The question asks which of the following were possible due to mammal's evolution in chewing structure and mechanics. Mammals have evolved specialized structures for chewing, which are not found in most other vertebrates. For instance, the evolution of heterodont teeth and cheek muscles has allowed mammals to mechanically break down their food more effectively, speeding up digestion and energy release.
Additionally, the adaptation of the secondary palate allows mammals to breathe while chewing, and changes to the jawbone, such as the development of the zygomatic arch, contribute to this process. Moreover, the modification of jawbones in mammals has led to the structure of the middle ear, with three tiny bones (the malleus, incus, and stapes) that convey sound vibrations more proficiently, giving mammals exceptional hearing.
Given the choices provided:
- A. Enables young mammals to suckle
- B. Whiskers binocular vision
- C. Facial expressions
- D. Improved inner ear
Option D is the correct answer as the improvements in chewing structure and mechanics directly relate to the evolution of the mammalian middle ear, which has three tiny bones that enhance their hearing abilities.