Ecological continuity between Lower and Upper Bed II, Olduvai Gorge, Tanzania

Area of Science:

• Paleoecology
• Paleontology
• Archaeology

Background:

• Olduvai Gorge Bed II sediments offer insights into early hominin environmental changes.
• Previous studies noted faunal community differences above and below the Lemuta Member tuff (~1.74 Ma).
• Hominin fossil density is lower in Bed II compared to Bed I, leading to less research.

Purpose of the Study:

• To investigate palaeoecological conditions during the transition between older and younger Bed II faunas.
• To analyze mammalian community ecological niche exploitation profiles and compare them to modern habitats.
• To assess environmental changes across the Lemuta Member disconformity in Olduvai Gorge.

Main Methods:

• Compilation of comprehensive species lists for older and younger Bed II faunas.
• Correspondence analysis of faunal assemblages to identify palaeoecological differences.
• Resampling of modern locality data with similar body mass profiles for discriminant analysis.

Main Results:

• Initial analysis indicated palaeoecological differences between pre- and post-Lemuta Member assemblages, neither representing forest habitats.
• After accounting for taphonomic body mass differences, ecological distinctions became less significant.
• Discriminant correspondence analyses suggest both fossil assemblages resemble modern woodland habitats, with Lower Bed II showing affinity to floodplain and marshy woodlands.

Conclusions:

• Woodland habitats were consistently important throughout Olduvai Gorge Bed II.
• Differences between older and younger Bed II faunas could originate from within a single modern habitat type.
• While increased aridity may have occurred post-Lemuta Member, woodland environments persisted.