84 research outputs found
Palaeoecological implications of the preservation potential of soft-bodied organisms in sediment-density flows: testing turbulent waters
No full textInterpreting how far organisms within fossil assemblages may have been transported and if they all originated from the same location is fundamental to understanding whether they represent true palaeocommunities. In a three-factorial experimental design, we used an annular flume to generate actualistic sandy sediment-density flows that were fast (2 ms−1) and fully turbulent in order to test the effects of flow duration, sediment concentration, and grain angularity on the states of bodily damage experienced by the freshly euthanized polychaete Alitta virens. Results identified statistically significant effects of flow duration and grain angularity. Increasing sediment concentration had a statistically significant effect with angular sediment but not with rounded sediment. Our experiments demonstrate that if soft-bodied organisms such as polychaetes were alive and then killed by a flow then they would have been capable of enduring prolonged transport in fast and turbulent flows with little damage. Dependent upon sediment concentration and grain angularity, specimens were capable of remaining intact over flow durations of between 5 and 180 min, equating to transport distances up to 21.6 km. This result has significant palaeoecological implications for fossil lagerstätten preserved in deposits of sediment-density flows because the organisms present may have been transported over substantial distances and therefore may not represent true palaeocommunities
Data from: Palaeoecological implications of the preservation potential of soft-bodied organisms in sediment-density flows: testing turbulent waters
No full textInterpreting how far organisms within fossil assemblages may have been transported and if they all originated from the same location is fundamental to understanding whether they represent true palaeocommunities. In a three-factorial experimental design, we used an annular flume to generate actualistic sandy sediment-density flows that were fast (2 ms−1) and fully turbulent in order to test the effects of flow duration, sediment concentration, and grain angularity on the states of bodily damage experienced by the freshly euthanized polychaete Alitta virens. Results identified statistically significant effects of flow duration and grain angularity. Increasing sediment concentration had a statistically significant effect with angular sediment but not with rounded sediment. Our experiments demonstrate that if soft-bodied organisms such as polychaetes were alive and then killed by a flow then they would have been capable of enduring prolonged transport in fast and turbulent flows with little damage. Dependent upon sediment concentration and grain angularity, specimens were capable of remaining intact over flow durations of between 5 and 180 min, equating to transport distances up to 21.6 km. This result has significant palaeoecological implications for fossil lagerstätten preserved in deposits of sediment-density flows because the organisms present may have been transported over substantial distances and therefore may not represent true palaeocommunities.,Table of experimental trials with recorded states of bodily damageExperimental combinations of flow duration, sediment concentration and grain angularity with corresponding recorded states of bodily damage.Table of raw data.docx</span
Preprint: Experimental protocol for validation of Computational Fluid Dynamics palaeoecological simulations
No full textSupplementary data associated with the preprinted publication 'Experimental protocol for validation of Computational Fluid Dynamics palaeoecological simulations' by Drage, Pates, and Minter (2025)
Palaeoecology of an Early Permian playa lake trace fossil assemblage from Castle Peak, Texas, USA
No full textTrace fossils: a fundamental framework and basic unit for quantifying ecosystem change
No full textOrganisms and their environments have been interacting and modifying one another since life began. The modification of an environment by one organism such that it affects other organisms is known as ecosystem engineering and such modifications can result in long-term changes that have evolutionary consequences. Behavioral interactions between organisms and sediments are one such type of ecosystem engineering and the importance of the effects were first realized by Charles Darwin. The results of behavioral interactions between organisms and sediments are recorded as trace fossils. As yet, trace fossils are an underutilized resource for studying environmental and ecosystem change and are largely underappreciated by those outside of the ichnological community. Here, I propose that trace fossils provide us with a fundamental framework and the basic unit for quantifying such changes. Just as there are many versions of the same play with different actors, we can still identify the play by the roles that are being performed and the same is true for trace fossils in that we can characterize an ecosystem regardless of the animals present. Unlike ecological studies involving body fossils, which are often temporally and spatially restricted, trace fossils enable us to compare ecosystems through time and across environments. The application of existing methods such as cluster analysis and the development of new numerical techniques for quantifying ecosystems based on trace fossils will allow us to tackle questions relating to ecosystem engineering through time, the colonization of different environments and the recovery from mass extinctions. It will also open up the use of animal traces in modern habitat mapping. Together, these will provide insights for future challenges to society in predicting the impacts of environmental change on ecosystems and biodiversity.Simposio IV: Icnología: su aporte en interpretaciones paleoecológicas y paleobiológicasFacultad de Ciencias Naturales y Muse
Ichnology of the nonmarine Permian : ichnotaxonomy, palaeoenvironments and palaeoethology of the southwest USA
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
Nest-seeking rock ants (<i>Temnothorax albipennis</i>) trade off sediment packing density and structural integrity for ease of cavity excavation
No full textWe investigated excavation and nest site choice across sediment-filled cavities in the ant Temnothorax albipennis. Colonies were presented with sediment-filled cavities, covering a spectrum from ones that should be quick to excavate but will form a weak enclosing wall to those that should be slow to excavate but form a strong wall. Overall, colonies only showed a significant preference for cavities that were fastest to excavate over those that were slowest. The speed of decision making and moving appears paramount over the suitability of the sediment for forming an enclosing wall. The mechanism behind the choice is the differential between the rates at which alternatives are excavated and accumulate ants. The rates for a particular type of cavity were unaffected by the type with which it was paired. This suggests that there is no significant competition between sites during the decision-making process. Certain colonies were able consistently to discriminate across more closely matched alternatives. These colonies required a greater number of ants to be present and took longer before beginning to move. A race is run between alternatives to become habitable but the process may be tuned across colonies such that it may run for longer and an incorrect or split decision is less likely.</p
Retelling racialized violence, remaking white innocence: the politics of interlocking oppressions in transgender day of remembrance
No full textTransgender Day of Remembrance has become a significant political event among those resisting violence against gender-variant persons. Commemorated in more than 250 locations worldwide, this day honors individuals who were killed due to anti-transgender hatred or prejudice. However, by focusing on transphobia as the definitive cause of violence, this ritual potentially obscures the ways in which hierarchies of race, class, and sexuality constitute such acts. Taking the Transgender Day of Remembrance/Remembering Our Dead project as a case study for considering the politics of memorialization, as well as tracing the narrative history of the Fred F. C. Martinez murder case in Colorado, the author argues that deracialized accounts of violence produce seemingly innocent White witnesses who can consume these spectacles of domination without confronting their own complicity in such acts. The author suggests that remembrance practices require critical rethinking if we are to confront violence in more effective ways. Description from publisher's site: http://caliber.ucpress.net/doi/abs/10.1525/srsp.2008.5.1.2
The fish swimming trace <i>Undichna unisulca</i> from the Silurian of Sweden: probably the oldest vertebrate locomotion trace fossil
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