Abstract:
The study area has excellent exposures of upper Jurassic sedimentary rock which is situated
in north western Ethiopian plateau. This research is focused on detail field investigation,
description and systematics of upper Jurassic bivalves for the reconstruction of depositional
environment and ecology. Different scientific methods were followed in order to achieve and
accomplish the stated research problem and the objectives of the study with three main
methods. These are pre-field work, detail main fieldwork and post field work.
Totally six hundred fifty-two specimens of fossil bivalves have been collected and fifty-four
representative samples were prepared for systematic paleontology by identifying down to
species level where possible from the Antalo limestone formations in the Blue Nile Basin from
three sections with two associations. The sections from which the specimens have been
collected include Filikilik section (31%), Demibeza section (48%) and Geligele section (21%).
Twenty-one bivalve species have been identified and described systematically and they are
belonging to two superfamily, nineteen family, three subfamily, eighteen genera, four
subgenera. From the twenty one species, 16 species belong to Demibeza section (Pholadomya
socialis, Bucardiomya somaliensis, Pholadomya hemicardia, Pholadomya lirata, Pholadomya
aubryi, Pholadomya murchisoni, Pholadomya beamontensis, Palaeonucula lateralis,
Paleonucula cuneiformis, Pterotrigonia scabra, Liostrea acuminate, Eligmus asiaticus,
Actinostrean gregareum, Nanogyra nana, Nanogyra fourtaui and Ilmatogyra africana), six
species were identified from Filikilik (Modiolus bipartitus, Modiolus imbricatus, Paleonucula
cuneiformis, Pholadomya murchisoni, paleonucula lateralis and Nanogyra nana ) and six
species from Geligele (Nanogyra fourtaui ,Ilmatogyra africana, Nanogyra nana and Liostrea
acuminate, Graphaea balli and Exogyra fourtaui) are described systematically. Bivalves in
the study area represent mainly Basinal environments and deep shelf. No endemic species
were recorded from the studied sections
