What is the name of the later phase of the Old Stone Age?

The later phase of the Old Stone Age is known as the Upper Palaeolithic. This period, which began around 50,000 years ago and lasted until approximately 10,000 years ago, is characterized by significant advancements in tool technology, art, and social organization among early humans. During the Upper Palaeolithic, there was a notable increase in the diversity of stone tools, including blades and specialized weaponry, and the emergence of artistic expression as seen in cave paintings and carvings.

In contrast, the Lower Palaeolithic refers to the earliest phase of the Old Stone Age, where the first known stone tools appeared. The Mesolithic period is seen as a transitional stage between the Upper Palaeolithic and the Neolithic, marked by the development of more sedentary lifestyles and the beginnings of agriculture. The Neolithic represents a significant cultural shift marked by the domestication of plants and animals and the establishment of permanent settlements.

Thus, the Upper Palaeolithic is definitively regarded as the later phase of the Old Stone Age, making this answer the most accurate choice.