Final answer:
The Precambrian Earth experienced a vastly different atmosphere, notable geologic upheaval, volcanic activity, and Snowball Earth periods which impacted the evolution of early life forms. Space debris also caused massive impacts that could sterilize the planet, yet life persisted. Stromatolites provide evidence of early photosynthetic life after Earth's surface solidified and oceans formed.
Step-by-step explanation:
Based on the information provided, the Precambrian Earth underwent significant changes that influenced the development of early life. The atmosphere of early Earth was markedly different from what we see today, primarily with much less molecular oxygen. This early atmosphere was greatly affected by geologic upheaval and volcanic activity, creating harsh conditions that early prokaryotic life forms had to withstand. During the late Precambrian, a Snowball Earth event occurred, where the planet grew extremely cold and was covered by ice and snow, influencing life forms to develop new adaptations such as sexual reproduction and multicellularity to survive.
Further, Earth experienced large impacts from space debris during its formation, some of which were violent enough to nearly sterilize the planet, potentially wiping out nascent life forms and drastically altering the composition of both the atmosphere and the oceans. However, life managed to emerge after the solidification of Earth's molten surface and the formation of liquid oceans, indicated by the presence of stromatolites, the ancient fossilized remnants of colonial cyanobacteria. These details help us understand how early Earth was shaped and how the conditions on the planet served as a crucible for the evolution of life.