Fossils suggest that the first major trait distinguishing hominins from other primates was a. a larger brain. b. erect posture. c. forward-facing eyes with depth perception. d. tool making.

Verified step by step guidance

1. Identify the key traits that differentiate hominins from other primates. These include brain size, posture, eye orientation, and tool-making abilities.
2. Consider the evolutionary timeline and the appearance of these traits. Erect posture is a fundamental change that would likely appear before more complex behaviors such as tool making.
3. Evaluate how each trait would impact survival and adaptation to the environment. Erect posture allows for more efficient movement and energy use in open environments, which is crucial for survival.
4. Research the fossil evidence available for early hominins like Australopithecus to see which trait appears consistently and early in the fossil record.
5. Conclude which trait is most likely the first major distinguishing characteristic based on the earliest and most prevalent evidence in the fossil record.