Morphological taphonomic transformations of fossil bones in continental environments, and repercussions on their chemical composition

Abstract

The aim of this paper is to provide a summary of structural or surface modifications of vertebrate bone remains in continental palaeoenvironments that may have repercussions on their chemical composition. Both before and after burial, a different set of physical, chemical and biological agencies may produce modifications of the bone morphological structure and/or bone chemical composition. Several of these morphological modifications are diagnostic of particular agents, which otherwise may not be noticed or identified in a fossil association. In order to understand diagenesis, those events that occurred before final burial have to be considered, as they may strongly modify the bone morphological structure and influence post–burial changes.

Apatite Biominerals

“…After cell death, the first alteration is related to the destruction of the organic matrix by microorganisms and hydrolysis [141][142][143][144][145]. This process is of course important for tissues with a high content of organic components, such as fish scales and bones, and seems rather limited in the case of mature enamel.…”

“…Although the ions released by dissolution can certainly be locally reused at the precipitation loci, similar to the in vivo remodeling of bone, the system around the fossil is largely open and several foreign elements stabilizing the apatite structure such as fluorine, silicon, heavy metals (Pb, Ba) and rare earth elements play a determining role in this recrystallization, modify the apatite composition and characteristics [113]. The kinetics of these processes depend on the presence of groundwater, dissolved mineral ions, pH and temperature and also on the fossil apatite characteristics (composition, crystal size) and fossil porosity [141,144,147]. Thus small bones and trabecular bone are more strongly altered than cortical, compact bone.…”

The survival of organic matter in bone: a review

“…Passage through the stomach of an animal is one such process known to lead to acid hydrolysis and this leaves tell-tale signs on the bone (Denys et al 1995;Fernández-Jalvo et al 2002). In the burial environment, Collins et al (1995) assumed in their basic model of collagen degradation that extremes of pH would be mitigated by the mineral, which would act as a pH buffer.…”

Observações sobre a repartição espacial dos restos fósseis de preguiça-gigante (gênero Eremotherium) na Lagoa Uri de Cima, Pernambuco, Brasil

“…As raízes das plantas absorvem água carregada com íons minerais obtidos da degradação da matéria orgânica, incluída aquela dos restos ósseos soterrados. A associação simbiótica entre raízes e fungos (Mycorrizae) e/ou raízes e algumas bactérias (Rhizobium) é essencial para o crescimento da planta e a permite retirar vários elementos químicos da superfície óssea (Fernández-Jalvo et al, 2002), deixando marcas características.…”