The evolution of tail joint stiffness in oviraptorosaur dinosaurs and its consequences for tail fucntion

Poster Session 3: no. 36Oviraptorosaurs preserve distal tail fronds that are sometimes articulated with a fused pygostyle-like structure. This similarity with birds has led to speculation that they used their tails for display purposes, as in peacocks. The prezygapophyseal morphology and craniocaudally short centra of oviraptorosaur tails indicate a high degree of flexibility per unit of absolute tail length. Their prezygapophyses permitted a large range of motion per joint, which increased tail mobility because the craniocaudally shorter centra allowed the tail to accommodate more joints per unit length. The large muscle volumes reconstructed for oviraptorosaur tails presumably helped to actively stiffen or move them. We predict high passive joint stiffness in their tails because their great depth and breadth created longer moment arms for tissue to leverage its resistance against dorsally/ventrally or laterally directed joint rotation respectively. Shorter tails that evolved via craniocaudally shorter centra also lead to the same prediction because centrum length affects the ...postprin

Modulation Theory and Systems

Contains a report on a research project

Writing Toward Democracy: Service-Learning and Composition

This study will show how encouraging students to write toward democracy could help them to become better writers and citizens. Service-learning can help students learn to write through active inquiry, collaboration with different discourse communities, and consideration of their roles as citizens. However, service-learning must meet three challenges in order to be successful. First, I will argue that freshman composition\u27s subordinate status as a service course to the university can inhibit a pedagogy of service-learning. Even though service-learning may be a useful term to name this pedagogy, I propose that we find a different name in order to emphasize student writers as participants in democracy. We need to start thinking of our work in ways different from just service. We need to encourage students to write toward democracy. Next, service-learning and composition scholarship often emphasize a separation between academia and community, and this perception affects our discussion of discourse. We speak of academic discourse and public discourse as if they were two different languages. I will argue that separating academia from community, and separating academic from public discourse, create unnecessary problems. Drawing upon the work of Dewey, Barris, and others, I call for a “discourse for democracy ill which students choose to write about and act upon problems that matter to them. These kinds of writing assignments will help students to become better writers and also might help them to become better citizens. Finally, are we citizens of the world or citizens of countries or both? Responding to Martha Nussbaum\u27s essay about cosmopolitanism and her belief that our focus as educators should be “world citizenship, rather than democratic or national citizenship (11), I investigate possible definitions of citizenship. I will propose that our service-learning classes need to encourage students to write about their roles within a global community. This study, then, proposes three changes in the use of service-learning with an examination of the scholarship and examples from my teaching

Promoting the 3Rs to enhance the OECD fish toxicity testing framework.

Fish toxicity testing has been conducted since the 1860's in order to help define safe levels of chemical contaminants in lakes, rivers and coastal waters. The historical emphasis on acute lethality testing of chemicals has more recently focussed on long term sublethal effects of chemicals on fish and their prey species. Fish toxicity testing is now embedded in much environment legislation on chemical safety while it is recognized that animal use should be Replaced, Reduced and Refined (the 3Rs) where possible. The OECD Fish Toxicity Testing Framework provides a useful structure with which to address the needs of environmental safety assessment whilst implementing the 3Rs. This commentary aims to promote the implementation of the recommendations of the OECD Fish Toxicity Testing Framework

The extinct, giant giraffid Sivatherium giganteum – skeletal reconstruction and body mass estimation

Sivatherium giganteum is an extinct giraffid from the Plio–Pleistocene boundary of the Himalayan foothills. To date, there has been no rigorous skeletal reconstruction of this unusual mammal. Historical and contemporary accounts anecdotally state that Sivatherium rivalled the African elephant in terms of its body mass, but this statement has never been tested. Here, we present a three-dimensional composite skeletal reconstruction and calculate a representative body mass estimate for this species using a volumetric method. We find that the estimated adult body mass of 1246 kg (857—1812 kg range) does not approach that of an African elephant, but confirms that Sivatherium was certainly a large giraffid, and may have been the largest ruminant mammal that has ever existed. We contrast this volumetric estimate with a bivariate scaling estimate derived from Sivatherium's humeral circumference and find that there is a discrepancy between the two. The difference implies that the humeral circumference of Sivatherium is greater than expected for an animal of this size, and we speculate this may be linked to a cranial shift in centre of mass

Temporal and phylogenetic evolution of the sauropod dinosaur body plan

The colossal size and body plan of sauropod dinosaurs are unparalleled in terrestrial vertebrates. However, to date, there have been only limited attempts to examine temporal and phylogenetic patterns in the sauropod bauplan. Here, we combine three-dimensional computational models with phylogenetic reconstructions to quantify the evolution of whole-body shape and body segment properties across the sauropod radiation. Limitations associated with the absence of soft tissue preservation in fossils result in large error bars about mean absolute body shape predictions. However, applying any consistent skeleton : body volume ratio to all taxa does yield changes in body shape that appear concurrent with major macroevolutionary events in sauropod history. A caudad shift in centre-of-mass (CoM) in Middle Triassic Saurischia, associated with the evolution of bipedalism in various dinosaur lineages, was reversed in Late Triassic sauropodomorphs. A craniad CoM shift coincided with the evolution of quadrupedalism in the Late Triassic, followed by a more striking craniad shift in Late Jurassic–Cretaceous titanosauriforms, which included the largest sauropods. These craniad CoM shifts are strongly correlated with neck enlargement, a key innovation in sauropod evolution and pivotal to their gigantism. By creating a much larger feeding envelope, neck elongation is thought to have increased feeding efficiency and opened up trophic niches that were inaccessible to other herbivores. However, we find that relative neck size and CoM position are not strongly correlated with inferred feeding habits. Instead the craniad CoM positions of titanosauriforms appear closely linked with locomotion and environmental distributions, potentially contributing to the continued success of this group until the end-Cretaceous, with all other sauropods having gone extinct by the early Late Cretaceous

Electron Temperature of Ultracold Plasmas

We study the evolution of ultracold plasmas by measuring the electron temperature. Shortly after plasma formation, competition between heating and cooling mechanisms drives the electron temperature to a value within a narrow range regardless of the initial energy imparted to the electrons. In agreement with theory predictions, plasmas exhibit values of the Coulomb coupling parameter $\Gamma$ less than 1.Comment: 4 pages, plus four figure

Cypria petenensis, a new name for the Ostracod Cypria pelagica Brehm 1932

Recently during the preparation of a comprehensive account of the lake plankton (Hutchinson, in press) a rather unfortunate case of homonymy was discovered in the genus Cypria