Middle Pliocene hominin distribution patterns in Eastern Africa

Area of Science:

• Paleontology
• paleoecology
• Paleoanthropology

Background:

• Abundance distributions of large mammals are valuable but underutilized tools for understanding ecological pressures in the fossil record.
• Previous studies have not fully leveraged mammalian abundance data to reconstruct Pliocene environments and hominin habitats.

Purpose of the Study:

• To investigate variations in relative abundance across contemporaneous Pliocene mammal communities.
• To assess how ecological pressures differed between four Pliocene sites in the Afar and Turkana basins (Hadar, Omo Valley, East Turkana, West Turkana) between ~3.6 and 3.22 Ma.
• To determine hominin habitat preferences in relation to other mammals.

Main Methods:

• Examined taphonomic and collection biases using skeletal parts, body size, and taxonomic data.
• Calculated hominin relative abundance using a taphonomic control taxon to account for biases.
• Compared mammalian taxonomic groups to infer habitat associations at each site.

Main Results:

• Taphonomic and collection biases were present at all sites, with Turkana Basin sites showing particular collection bias.
• Mammalian communities varied, with the Omo region dominated by suids and cercopithecids (woodland-associated), and other sites by bovids (open/mixed habitat-associated).
• Hominin abundance was higher in mixed woodland/grassland environments (Hadar) and lower in woodland-dominated areas (Omo Valley). West Turkana showed high hominin abundance in mixed habitats, potentially influenced by sampling issues.

Conclusions:

• Early hominins, including Kenyanthropus platyops and Australopithecus afarensis, inhabited similar habitats across different rift basins.
• The findings support the hypothesis that early hominins diverged from great apes by moving away from woodland-dominated environments.
• Mammalian abundance data provides crucial insights into paleoecology and early hominin behavior.