Microfaunal remains from a modern east African raptor roost: patterning and implications for fossil bone scatters

Paleobiology ◽  
1999 ◽  
Vol 25 (4) ◽  
pp. 483-503 ◽  
Author(s):  
Kathlyn M. Stewart ◽  
Leola Leblanc ◽  
Diana P. Matthiesen ◽  
Jolee West
Keyword(s):  
Taxonomic Composition ◽  
Olduvai Gorge ◽  
Distinctive Pattern ◽  
Late Cenozoic ◽  
Aquatic Birds ◽  
East African ◽  
Lake Turkana ◽  
Fossil Bone ◽  
Element Profile ◽  
Faunal Diversity

Fish eagles (genus Haliaeetus) potentially have contributed the bones of their prey to many late Cenozoic concentrations of vertebrate microfossils. To evaluate possible biases in the taxa and skeletal elements preserved in assemblages accumulated by fish eagles, which could affect paleoecological and evolutionary interpretations derived from Cenozoic microfaunal localities, a sample of 1883 bones accumulated by modern African fish eagles (H. vocifer) was collected from a roost near Lake Turkana, Kenya. Characteristics of the bone assemblage include (1) taxonomic composition dominated by fish; (2) diverse but small-sized and ecologically restricted animals including inshore fish, aquatic birds, very small nocturnal mammals (which may have been contributed by other raptors), and small reptiles (possible predators on the roost); (3) poor survivorship for specific categories of skeletal elements; (4) considerable bone breakage for all but the smallest animals; and (5) a distinctive pattern of postcranial fragmentation for bird and mammal elements. The fish eagle element profile has some similarities to those of other diurnal raptors, but its cumulative signature can be distinguished from those of other bone accumulators and includes characteristics that would also be manifest in fossil assemblages. Examination of fossil microfaunas from the Plio-Pleistocene localities of Kanapoi (Kenya), Inolelo (Tanzania), and Olduvai Gorge (Tanzania) shows that the patterns of element preservation for Kanapoi and Inolelo do not match those of the Lake Turkana fish eagle roost. Nonetheless, some aspects of the Olduvai Gorge FLKN assemblage show taxonomic and skeletal similarites. In light of the selective choices of prey by fish eagles, the fauna recovered from Olduvai Gorge FLKN might not accurately reflect faunal diversity or patterns of abundance at this locality during the Pleistocene. Because fish eagles of the genus Haliaeetus are found on three continents, have a fossil record extending to the Miocene, and deposit bones in a habitat conducive to preservation, the taxa preserved at many other late Cenozoic microfaunal sites also might be biased. Therefore, taphonomic profiles of late Cenozoic microfaunal assemblages should be compared against the taphonomic profiles typical of fish eagle roosts before faunal characterizations of sites are applied in analyses of paleoecological evolution.

Algal composition and biomass in the tropical soda lake Chitu with focus on seasonal variability of Arthrospira fusiformis (Cyanophyta)

2016 ◽  
Vol 67 (4) ◽  
pp. 483 ◽  
Author(s):  
Tadesse Ogato ◽  
Demeke Kifle ◽  
Brook Lemma
Keyword(s):  
Seasonal Variability ◽  
Soda Lakes ◽  
Soda Lake ◽  
Dry Weight ◽  
Taxonomic Composition ◽  
Algal Community ◽  
Environmental Drivers ◽  
East African ◽  
Chl A ◽  
Algal Abundance

The vital ecological functions of the East African soda lakes are much dependent on Arthrospira, which forms a natural nearly monoalgal populations and serves as the main diet for the huge flocks of flamingos in the present study lake Chitu (Ethiopia). This study investigated algal taxonomic composition and biomass, and the seasonal variability in the abundance of Arthrospira fusiformis in response to some environmental drivers (e.g. rainfall, salinity and nutrients) using samples collected over an annual cycle. The algal community was composed of a few taxa (15 species), with exclusive dominance of A. fusiformis. Chlorophyll-a (Chl-a) and dry weight, and abundance of A. fusiformis were notably high and exhibited seasonal variations, with significantly (P<0.05) higher levels of Chl-a and dry weight during the rainy season. The observed strong correlations of algal abundance and biomass with rainfall (positively) and alkalinity-salinity (negatively), probably suggest that hydrological control of the salinity is the major driving force for the seasonal variability of A. fusiformis in the lake. Further hydrological modifications that enhance salinisation may greatly affect A. fusiformis thereby causing instability of the flamingos with eventual impairment of the ecosystem values of the lake.

Zebras (Genus Equus) from nine Quaternary sites in Kenya, East Africa

1981 ◽  
Vol 18 (2) ◽  
pp. 330-341 ◽  
Author(s):  
C. S. Churcher
Keyword(s):  
East Africa ◽  
Rift Valley ◽  
Olduvai Gorge ◽  
East African ◽  
Northern Kenya ◽  
Lake Magadi ◽  
Tana River ◽  
The Common ◽  
Grevy’S Zebra

The Olduvai zebra, Equus oldowayensis, is identified or confirmed from the following sites: Olorgesailie, Lake Magadi; Marsabit Road, Northern Kenya; Chemoigut Beds (Chesowanja), Baringo Basin; Wajir, Northeast Kenya; Bura, Tana River; Makalia River (MacInnes Site), Rift Valley; Legetet, Koru; Karmosit, Suguta River; and Kanjera, Homa Mountain, all in Kenya, on the evidence from isolated teeth and other fragments. Burchell's zebra, E. burchellii, appears to have been absent from all the sites except possibly Olorgesailie and the Chemoigut Beds.E. oldowayensis is known from about 1.8 Ma ago in Bed I at Olduvai Gorge and from about 1.9 Ma ago in the Shungura Formation (Member G) in the Omo deposits, before which no reliable records are recognised. It was the common and dominant zebra of the latest Pliocene and Pleistocene in the East African plains and was replaced by the present common zebra, E. burchellii, only during the latest Pleistocene and Holocene times. E. oldowayensis is similar to modern Grevy's zebra, E. grevyi, to which it gave rise, and these two zebras are not directly related to Burchell's zebra.

URANIUM VARIATIONS IN A DATED FOSSIL BONE SERIES FROM OLDUVAI GORGE, TANZANIA

Archaeometry ◽  
1974 ◽  
Vol 16 (2) ◽  
pp. 129-135 ◽  
Author(s):  
M. G. SEITZ ◽  
R. E. TAYLOR
Keyword(s):  
Olduvai Gorge ◽  
Fossil Bone

scholarly journals Ichthyofaunal diversity of the Omo-Turkana basin, East Africa, with specific reference to fish diversity within the limits of Ethiopian waters

Check List ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 2059 ◽  
Author(s):  
Mulugeta Wakjira ◽  
Abebe Getahun
Keyword(s):  
Native Species ◽  
River System ◽  
Specific Reference ◽  
Fish Diversity ◽  
East African ◽  
Lake Turkana ◽  
Turkana Basin ◽  
Northern Portion ◽  
Omo River ◽  
Annotated Checklist

The freshwaters of the East African nation of Ethiopia are divided into nine main drainage basins. One of these, the Omo-Turkana basin, spans a large part of southwestern Ethiopian highlands and northern Kenya, and consists of the Omo-Gibe (or simply, Omo) River and a northern portion of Lake Turkana. Despite some development activities, including proposed dam construction with potential impacts on ichthyofaunal diversity, the Ethiopian part of the basin generally lacks comprehensive study or full scientific documentation. During the current surveys 31 species were identified from the lower Omo River and Ethiopian part of Lake Turkana, with some new records for the basin. The Omo River system was found to be richer in species while Lake Turkana has a higher abundance. Ichthyofaunal diversity within Ethiopian waters is specifically addressed, and an annotated checklist for native species of the basin is provided.

Ecological, taxonomic, and taphonomic components of the post-Paleozoic increase in sample-level species diversity of marine benthos

Paleobiology ◽  
2006 ◽  
Vol 32 (4) ◽  
pp. 533-561 ◽  
Author(s):  
Michał Kowalewski ◽  
Susan L. Barbour Wood ◽  
Wolfgang Kiessling ◽  
Martin Aberhan ◽  
Franz T. Fürsich ◽  
...  
Keyword(s):  
Fossil Record ◽  
Empirical Work ◽  
Alpha Diversity ◽  
Taxonomic Composition ◽  
Taxonomic Structure ◽  
Late Cenozoic ◽  
Time Intervals ◽  
Data Set ◽  
Marine Benthos ◽  
Sampling Procedures

Biological veracity of the sharp diversity increase observed in many analyses of the post-Paleozoic marine fossil record has been debated vigorously in recent years. To assess this question for sample-level (“alpha”) diversity, we used bulk samples of shelly invertebrates, representing three major fossil groups (brachiopods, bivalves, and gastropods), to compare the Jurassic and late Cenozoic sample-level diversity of marine benthos. After restricting the data set to single-bed, whole-fauna, bulk samples (n≥ 30 specimens) from comparable open marine siliciclastic facies, we were able to retain 427 samples (255 Jurassic and 172 late Cenozoic), with most of those samples originating from our own empirical work.Regardless of the diversity metric applied, the initial results suggest that standardized sample-level species (or genus) diversity, driven by evenness and/or richness of the most common taxa, increased between the Jurassic and late Cenozoic by at least a factor of 1.6. When the data are partitioned into the three dominant higher taxa, it becomes clear that (1) the bivalves, which dominated the samples for both time intervals, increased in sample-level diversity between the Jurassic and the late Cenozoic by a much smaller factor than the total fauna; (2) the removal of brachiopods, which were a noticeable component of the Jurassic samples, did not significantly affect standardized sample-level diversity estimates; and (3) the gastropods, which were rare in the Jurassic but common in many late Cenozoic samples, contributed notably to the increase in sample-level diversity observed between the two time intervals. Parallel to these changes, the samples revealed secular trends in ecological structure, including Jurassic to late Cenozoic increases in proportion of (1) infauna, (2) mobile forms, and (3) non-suspension-feeding organisms. These trends mostly persist when data are restricted to bivalves.Supplementary analyses indicate that these patterns cannot be attributed to sampling heterogeneities in paleolatitudinal range, lithology, or paleoenvironment of deposition. Likewise, when data are restricted to samples dominated by species with originally aragonitic shells, the observed temporal changes persist at a comparable magnitude, suggesting that the pervasive loss of aragonite in the older fossil record is unlikely to have been the primary cause of the observed patterns. The comparable ratio of identified to unidentified species and genera, observed when comparing the Jurassic and late Cenozoic samples, indicates that the relatively poorer (mold/cast) preservation of Jurassic aragonite species also is unlikely to have been responsible for the observed patterns. However, the diagenesis-related taphonomic and methodological artifacts cannot be ruled out as an at least partial contributor to the observed post-Paleozoic changes in diversity, taxonomic composition, and ecology (the outcomes of the three tests of the diagenetic bias available to us are incongruent).The study demonstrates that the post-Paleozoic trends in the sample-level diversity, ecology, and taxonomic structure of common taxa can be replicated across multiple studies. However, the diversity increase estimated here is much less prominent than suggested by many previous analyses. The results also narrow the list of causative explanations down to two testable hypotheses. The first isdiagenetic bias—a spurious trend driven by either (a) increasing taphonomic loss of small specimens in the older fossil record or (b) a shift in sampling procedures between predominantly lithified rocks of the Mesozoic and predominately unlithified, and therefore sievable, sediments of the late Cenozoic. The second hypothesis isgenuine biological changes—macroevolutionary trends in the structure of marine benthic associations through time, consistent with predictions of several related models such as evolutionary escalation, increased ecospace utilization, and the Mesozoic marine revolution. Future studies should focus on testing these two rival models, a key remaining challenge for identifying the primary causative mechanism for the long-term changes in sample-level diversity, ecology, and taxonomic structure observed in the Phanerozoic marine fossil record.

Archaeology of Early Pastoralism in East Africa

2021 ◽  
Author(s):  
Peter Robertshaw
Keyword(s):  
East Africa ◽  
Domestic Animals ◽  
Archaeological Sites ◽  
East African ◽  
Lake Turkana ◽  
Northern Tanzania ◽  
Stage Process ◽  
Pastoral Neolithic ◽  
Humid Period ◽  
Demic Diffusion

The first East African pastoralists arrived at the shores of Lake Turkana soon after the end of the African Humid Period, about 5,000 years ago. In the preceding millennia of the Holocene, fishing economies characterized East Africa. The domestic animals of the early pastoralists were not indigenous to East Africa, nor did they spread through the region simultaneously. Early pastoralist archaeological sites around Lake Turkana comprise settlements and remarkable monumental cemeteries. The expansion of pastoralists further south through East Africa was a two-stage process, probably because of the challenges posed by the presence of diseases fatal to livestock. First, caprines spread south and appear to have been integrated into existing forager subsistence systems. Then, starting toward the end of the 2nd millennium bce, specialized pastoralism began to be established across central and southern Kenya and into northern Tanzania. While analysis of lipid residues on potsherds has demonstrated that these Pastoral Neolithic (PN) peoples milked their animals, the question of whether agriculture was also practiced remains unresolved. Analyses of ancient DNA have shown there were at least two episodes of demic diffusion associated with the spread and establishment of the PN in East Africa. Considerable diversity is present in the PN, with three distinct cultures generally recognized across East Africa south of Lake Turkana. Moreover, there is even greater diversity observed in the decoration and shapes of ceramics. However, this cultural diversity is not matched by human genetic diversity, at least among the analyzed skeletons from two of the three cultures—the Elmenteitan and the Savanna Pastoral Neolithic.

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