Sahelanthropus tchadensis has two human anatomical traits: small canine teeth, and a spinal cord hole in the cranium further forward (on the underside of the cranium). It is possible that they are the fist of our ancestors to walk upright. If not, they likely had an intermediate stride.

Survival: From about 7 to 6 MYA in Central Africa (a densely wooded rain forest at the time)
Size: 4′ to 4’6″ (a little taller than modern chimpanzees)
Brain Size: around 320 to 380 cm³ (speculative)
Brain to Body EQ: Unknown, but like similar to chimpanzees at 2.2 to 2.5 (humans=7.4 to 7.8)

Perhaps the first species below represents Sahelanthropus tchadensis: