Final answer:
Paranthropus boisei is the hominin known for having a nearly pure C4 dietary signal. This species had a diet heavily reliant on C4 plants, with isotopic analyses of tooth enamel indicating an almost exclusive reliance on these sources.
Step-by-step explanation:
Which hominin has a nearly pure C4 signal?
Among hominins, the one known for a nearly pure C4 dietary signal is Paranthropus boisei. This species, which is not mentioned directly in the provided information, is characterized by its robust skull features and evidence suggests that it had a diet that heavily relied on C4 plants, such as grasses or sedges. The term 'C4 signal' refers to the distinctive chemical signature found in the remains of organisms that consumed C4 photosynthesis plants. Although Paranthropus aethiopicus has been mentioned as having characteristics of both robust and gracile australopithecines, it is Paranthropus boisei that is the most associated with the C4 dietary pattern based on isotopic analyses of fossilized tooth enamel.
It is important to note that other hominins, including earlier species like Australopithecus or Homo genus members, also included C4 plants in their diet to varying extents. However, Paranthropus boisei stands out because isotopic analysis indicates an almost exclusive reliance on C4 sources. This information helps paleoanthropologists understand the adaptation and ecological niches of various hominin species.