Volumen 4. Issue 1. Year 2006.

2020-03-28T19:17:25+02:00octubre 26th, 2019|Volumen 4. Issue 1. Year 2006.|

VOLUME 4. NUMBER 1. 2006

Dissolution Behavior of Calcareous Nannoplankton and Possible Alteration of Their Assemblages.

Kyoma Takahashi-Shimase, Satoru Nakashima.


[+info] VOLUME 4. ISSUE 1. 2006 (1 issue)

In order to evaluate alteration of calcareous nannoplankton assemblages during their deposition-diagenesis, a dissolution experiment of calcareous nannoplankton from a marine sediment sample was carried out. An assemblage of calcareous nannoplankton (coccoliths) found in surface sediments taken from the Caribbean Sea was put in stirred pure water with a fixed ionic strength (0.7 mol/l KCl) at 27.5°C to trace their dissolution behaviors. Temporal changes in pH and Ca concentration during the dissolution experiment indicated that the dissolution kinetics were similar to those found in the simple calcite system. By counting numbers of different species and taxonomic groups, the apparent dissolution rates were determined for each species and taxonomic group. The obtained individual dissolution rates differ among different species and taxonomic groups up to a factor of about 9. The resulted nannoplankton assemblages after dissolution were therefore very different from the original ones. This implies that the fossil assemblage can be altered during the deposition-diagenesis by carbonate dissolution processes.

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The Taphonomy of the Micromammals from the Late Middle Pleistocene Site of Hoedjiespunt 1 (Cape Province, South Africa).

Thalassa Matthews, John E. Parkington, Christiane Denys.


[+info] VOLUME 4. ISSUE 1. 2006 (2 issue)

The palaeontological site of Hoedjiespunt 1 (HDP1) has been dated to the late Middle Pleistocene. The rich mammalian fauna, recovered from the site, including four hominid teeth, is believed to have been accumulated by a hyaena. Micromammals were recovered from within the same horizons as the macro fauna. Previous analyses of the micromammals from the hyaena lair did not include a taphonomic analysis, and the agent of accumulation was assumed to be the hyaena responsible for the accumulation of the larger mammals. This assumption had not, however; been verified by a taphonomic analysis of the micromammal assemblages. A taxonomic and taphonomic study was thus carried out on the HDP1 micromammals in order to identify the predator(s) or agents responsible for the micromammal accumulation, and to evaluate the suitability of the assemblage for palaeoenvironmental analysis. The general pattern of species distribution of the murids from the two main fossil-bearing horizons at Hoedjiespunt 1 suggests that the micromammals have come from the same, original assemblage. The similarity observed in the micromammal taxonomy of these horizons is echoed in the taphonomy. The digestion on prey incisors, together with the range and activity patterns of prey species, suggests that the predator responsible for the fossil accumulation was a barn owl. The assemblage may provide a brief window into the micromammal population living on the west coast, in the immediate vicinity of the site, during the late Middle Pleistocene.

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Middle-Range Theory in Paleolithic Archaeology: The Past and the Present.

Levent Atici


[+info] VOLUME 4. ISSUE 1. 2006 (3 issue)

Middle-range theory (MRT), as the concept of intermediate theory between observed empirical data and general theories, was first formulated by the sociologist R.K. Merton in the context of the positivist waves of the 1960s as a reaction to the doctrinaire and descriptive paradigms of previous decades. Among the first archaeologists to employ this concept was L.R. Binford, whose work was particularly influential in the subsequent development of MRT in archaeology. Understanding site formation processes and the mechanisms responsible for generating, modifying and destroying traces of the past has been equated with MRT, particularly in Paleolithic archaeology. The development of MRT has played a crucial role in the formation and elaboration of field techniques, research designs, and new methodologies and, as such, has stimulated new directions and new questions in Paleolithic archaeology. This paper elaborates the definition of middle-range theory and discusses its development and application by archaeologists. Relevant components of MRT such as ethnographic analogy, ethnoarchaeology, experimental archaeology, taphonomy, and uniformitarianism are addressed, and some representative case studies are presented.

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Volumen 5. Issue 1. Year 2007.

2020-03-28T19:18:24+02:00octubre 26th, 2019|Volumen 5. Issue 1. Year 2007.|

VOLUME 5. NUMBER 1. 2007

Micromammals: When Humans are the Hunters.

Genevieve Dewar, Antonietta Jerardino.


[+info] VOLUME 5. ISSUE 1. 2007 (1 issue)

Analysis of the faunal remains from KV502, a Later Stone Age occupation site in Namaqualand, South Africa yielded an assemblage dominated by micromammal cranial remains. The material from KV502 was compared to an assemblage of microfauna collected from the stomach area of a human burial from the same general region. This consisted entirely of post-crania. The pattern of relative abundance of elements, the degree of fragmentation of the long bones, and the level of acid etching observed in the remains of the human burial can be used to identify micromammals consumed by humans. The complementary pattern (or evidence) for processing micromammal remains by humans is identified at KV502. Further, it was determined that from the degree of modification to the bones, humans should be considered a category 5 predator following Andrews' (1990) classification. This increases the database of possible predators of micromammals, which is important when using microfauna to determine palaeoenvironments, as the preferential 'tastes' of a predator will bias the species list.

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Quantification and Age Structure of Semi-Hypsodont Extinct Rodent Populations.

Katerina Vasileiadou, Jerry J. Hooker, Margaret E. Collinson.


[+info] VOLUME 5. ISSUE 1. 2007 (2 issue)

A new method of calculating the MNI and a full lifespan mortality profile in assemblages of semi-hypsodont rodents is proposed. Fossil jaws of the Paleogene theridomyid genera Isoptychus, Theridomys? and Pseudoltinomys show similar patterns of dental replacement, eruption and wear for all three genera. Deciduous premolars on the point of being replaced by their permanent successors coexist in jaws with erupting, unworn, unrooted third molars. The minimum number of individuals (MNI) in a theridomyid assemblage, of which the local origin is demonstrated, can therefore be calculated using the sum of deciduous premolars plus the most abundant of the permanent premolars or third molars. The teeth used to estimate the MNI of a species can also be used for the construction of its mortality profile. The ratio of an age-dependent crown height measurement to an age-independent crown width measurement is used as an age proxy for the establishment of 'age groups'. Wear patterns correspond well to age groups and, thus, broken unmeasurable specimens need not be excluded, as their wear stage can be used to assign them to 'age groups'.
Using these methods, the MNI and mortality profiles of one Isoptychus sp. and two Thalerimys fordi assemblages from the Late Eocene Solent Group (Hampshire Basin, Isle of Wight, southern England) were reconstructed. The mortality is attritional, showing a characteristic 'U-shape' in the distribution of the individuals in 'age groups'. The members of the three species, therefore, died of biological natural causes and not by a catastrophic event. This method can be applied to fossil semi-hypsodont micromammalian species, provided dental ontogeny is known. The method enables the construction of mortality profiles for the complete age range and, consequently, allows the analysis of the accumulation mechanisms of assemblages of semi-hypsodont rodents, with deciduous and permanent premolars. It can readily be applied to assemblages consisting only of isolated teeth.

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Estimating the preservation of tooth structures: towards a new scale of observation.

Yannicke Dauphin, Stéphane Montuelle, Cécile Quantin, Pierre Massard.


[+info] VOLUME 5. ISSUE 1. 2007 (3 issue)

For a better understanding of the fossilization processes and the paleoenvironmental records, knowing the state of preservation of fossil structures is essential. This paper presents how the analysis of tooth structures can be improved by using techniques increasing spatial resolution and accuracy, like atomic force microscopy (AFM). Micro- and nanostructural changes of the fresh and fossil dentine and enamel of two Suidae were thus observed with scanning electron (SEM) and atomic force microscopes. AFM and SEM show similar images for enamel and dentine in fresh teeth, whereas discrepancy occurs for fossil teeth. Both techniques show that dentine is modified by taphonomic and diagenetic processes, but only AFM is able to reveal that enamel is also altered, because AFM magnification and resolution are better than SEM ones. The apparent state of tissue preservation depends on the scale of observation and AFM, an analytical tool and a non-destructive/direct technique, allows a better understanding of the evolution of tissues at a nano-scale.

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The Taphonomist´s Corner: Make hay while the sun shines.

David K. Ferguson


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Ir a Arriba