Penis
Domestic cats have barbed penises, with about 120–150 one millimeter long backwards-pointing spines. Upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for ovulation. Lions also have barbed penises. Male felids urinate backwards by curving the tip of the glans penis backward. When male cheetahs urine-mark their territories, they stand one meter away from a tree or rock surface with the tail raised, pointing the penis either horizontally backward or 60° upward.
Cerebral cortex
The cerebral cortex is folded in a way that allows a large surface area of neural tissue to fit within the confines of the neurocranium. When unfolded, each hemispheric cortex has a total surface area of about . The folding is inward away from the surface of the brain, and is also present on the medial surface of each hemisphere within the longitudinal fissure. Most mammals have a cerebral cortex that is convoluted with the peaks known as gyri and the troughs or grooves known as sulci. Some small mammals including some small rodents have smooth cerebral surfaces without gyrification.