Evolution of Plio-Pleistocene Proboscidea From the Lower Omo Shungura Formation
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Date
2015-12-12
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Addis Ababa University
Abstract
The Shungura Formation is a Plio-Pleistocene paleontological site found in southern
Ethiopia, in the Lower Omo Basin, and well known for its abundant mammalian fossil record as
well as continuity of the stratigraphic sequence. It is one of the best sites which is radiometrically
well dated. It yielded abundant mammalian fossils among these Proboscidea were common
elements; there were seven proboscidean species (Anancus kenyensis, Stegodon kaisensis,
Elephas ekorensis, Deinotherium bozasi, Elephas recki, Loxodonta exoptata, and Loxodonta
adaurora) that went extinct during Pleistocene.
The comparative description on old Omo collection maxillary associated right and left
molars, mandibular associated left molar and the recently discovered fragmentary mandibular
associated molars recovered from the Shungura was compared with complete and nearly
complete molar specimens their taxa. Dental metric measurements were conducted from the
original materials of Shungura and metric data were compared as illustrated in table 4.13.
Morphological observations were made both from the original and published materials from
contemporaneous sites in eastern Africa such as Koobi Fora, Shungura, Allia Bay and Middle
Awash. The Morphological description and metric comparison of the dental materials from the
Shungura confirm that the relationships among the three taxa in eastern African sites changed at
the same rate through their evolution.
Results from the biometric analysis indicate that, different subspecies of Elephas recki
show statistically significant evolutionary changes in terms of the biometric traits. Generally, the
results show that there is no clear progressive increase in crown height. Instead, some sudden
changes in morphological features and no progressive trends in the lineage of Elephas recki
throughout the Plio-Pleistocene of Shungura were observed.
V
The results from the mesowear angle analysis of this study show that, there is no
significant difference in the mean mesowear angle values (ranging from 120 o to 130o) of the
entire lineage of Elephas recki through Plio-Pleistocene in the Shungura. These mean mesowear
angle values in general indicated that, Elephas recki adapted consistently to C4 dominated diet
during their evolution.
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Keywords
Shungura, Elephas, Biometrics, Dental Morphology, Mesowear, Paleodiet, Paleoenvironments