A GIS based approach to long bone breakage patterns derived from marrow extraction.

In archaeological assemblages the presence of percussion marks, on the surface of long bones, is an indicator of long bone marrow extraction. The form, quantity and distribution of percussion marks are analysed to gain a better understanding of the marrow extraction process. Patterns of bone percussion damage in archaeological assemblages may highlight standardized actions, possibly related to butchery traditions. However, additional factors could underlie these patterns and should also be considered. In this article we test intuitiveness as a factor in appearance of percussion mark patterns, to see if patterns can appear when bones are being fractured without prior experience with bone fracture properties. To test this hypothesis, for this study we selected a sample of 40 cattle (Bos taurus) long limb bones from a large bone breakage experiment (400 long limb bones), where participants had no previous experience in bone breakage and may thus have broken bones intuitively. We used Geographic Information System (GIS) software to analyse the distribution of percussion marks. Using ArcGIS Spatial Analysts tools, we identified and quantified significant concentrations of percussion marks. Results show that percussion mark patterns emerge for the same bone element, and that specific sides and zones were recurrently selected by experimenters. The distribution of patterns varies among the different long bone elements, and we attribute this variance to an adjustment to bone morphology. In addition, we calculated and identified bone damage patterns resulting from hammerstone percussion. Crossing bone survivorship with percussion mark patterns enabled us to recognise and evaluate the effects of fragmentation and surface visibility in controlled experimental conditions. The GIS method facilitates comparisons between different variables and provides a sophisticated visual representation of results. Enlarging the sample will allow to constitute a more substantial analogous model for fossil assemblages.

Cytogenetic repartition of chicken CR1 sequences evidenced by PRINS in Galliformes and some other birds.

Chicken repeat 1 (CR1) belongs to the non-long repeat class of retrotransposons. Nearly 100000 repeats interspersed in the chicken genome are subdivided into at least six distinct subfamilies, each 300 bp long and all sharing substantial sequence similarity. CR1-like elements were found in genomes from invertebrates to mammals, suggesting their importance for genome structure and/or function. Moreover, numerous data support the hypothesis of their implication in regulation of gene expression. So, the chromosomal distribution of these CR1 sequences in vertebrates is of great interest to improve our knowledge about the genome structure, function and evolution. A comparison of the cytogenetic distribution of CR1 sequences was performed by PRINS using consensus chicken primers on the chromosomes of chicken and species of several bird orders: Galliformes, Anseriformes, Passeriformes and Falconiformes. The study revealed that CR1 repeats are spread over nearly all chicken chromosomes with a higher density on the macrochromosomes and in particular with hot spots on subtelomeric regions of chromosome 1, 2, 3q, 4q, 5q. Their distribution on the macrochromosomes forms a kind of banding pattern, which was not systematically matched with R- or G-banding. This banding pattern appears to be conserved on the chromosomes of the Galliformes studied, irrespective of their karyotypes, rearranged or not. CR1 primers also show similar signals on the chromosomes of birds phylogenetically more distant (Anseriformes, Passeriformes and Falconiformes). This fact confirms the importance of these sequences at the large scale of bird evolution and in the chromosomal structure. The location of CR1 sequences, and in particular of the hot spots, mainly within the richest CG areas are in conformity with the data on an epigenetic role of these highly conserved sequences.