150 million years ago to 100 million years ago, mammals {insectivore}| (Insectivora) evolved that ate insects. Early ones {primitive insectivores} look like tree shrews.
vision
Insectivores have forward vision, with eyes facing front rather than on side, allowing stereoscopic vision and space for larger frontal lobes.
hand
Insectivores have grasping hands, with opposing thumb across from fingers, for more eye-hand coordination and precise hand and arm movements.
evolution
Primitive insectivores evolved from placental mammals. Primates evolved from primitive insectivores.
types
Insectivores include mole, hedgehog, and shrew.
Mammals {mole, mammal} (Phacoschoerus) (Talpidae) (Chrysochloridae) can live underground, be nocturnal, and have front digging paws. Star-nosed moles have quickly moving touch organ in front. 22 arms have 25,000 Eimer's organs, which are similar to Pacinian corpuscles and contain touch receptors. Free-nerve-ending touch receptors are for vibration and contact. Merkel-cell touch receptors are for pressure. Both are in all mammals. Moles have free nerve endings in a circle, used for detecting texture. The most-sensitive arm matures first and is larger in embryos. Skin surfaces probably had such strips in mammal predecessors.
Small mouse-like mammals {shrew, primate} {tree shrew} (Soricidae) can have a long pointed snout.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225