Colin Palmer

University of Bristol | UB · School of Earth Sciences

Launch is the most energetically expensive part of flight and is considered a limiting factor in the size of modern flyers. Pterosaurs reached significantly larger sizes than modern flyers and are proposed to have launched either bipedallly or quadrupedally. We investigated the ability of a medium-sized ornithocheiraean pterosaur to assume the pose...

Various Mesozoic marine reptile lineages evolved streamlined bodies and efficient lift-based swimming, as seen in modern aquatic mammals. Ichthyosaurs had low-drag bodies, akin to modern dolphins, but plesiosaurs were strikingly different, with long hydrofoil-like limbs and greatly variable neck and trunk proportions. Using computational fluid dyna...

Although extant land birds take to the air by leaping, generating the initial take-off velocity primarily from the hindlimbs, the detailed musculoskeletal mechanics remain largely unknown. We therefore simulated in silico the take-off leap of the zebra finch, Taeniopygia guttata, a model species of passerine, a class of bird which includes over hal...

Take-off is a critical phase of flight, and many birds jump to take to the air. Although the actuation of the hindlimb in terrestrial birds is not limited to the sagittal plane, and considerable non-sagittal plane motion has been observed during take-off jumps, how the spatial arrangement of hindlimb muscles in flying birds facilitates such jumps h...

Bird feather shafts are light, stiff, and strong, but the fine details of how their structure, mechanics and function relate to one another remains poorly understood. The missing piece in our understanding may be the various fibrous layers that make up the shaft's cortex. Detailed imaging techniques are needed to enable us to capture, analyse and q...

Ichthyosaurs are an extinct group of fully marine tetrapods that were well adapted to aquatic locomotion. During their approximately 160 Myr existence , they evolved from elongate and serpentine forms into stockier, fish-like animals, convergent with sharks and dolphins. Here, we use computational fluid dynamics (CFD) to quantify the impact of this...

Birds often accumulate large fat and protein reserves to fuel long-distance flights. While it is well known that species that fly the longest accumulate the largest amounts of fuel, considerable cross-species variation in fuel load is seen after controlling for overall migration distance. It remains unclear whether this variation can be explained b...

Body mass estimates provide valuable information about the ecology and biomechanics of extinct animals. They have particular importance for flying animals, as mass directly influences flight capabilities, and so behaviour. For pterosaurs, which include the largest animals ever to have flown, previous methods of mass estimation have produced a wide...

The extinct ocean-going plesiosaurs were unique within vertebrates because they used two flipper pairs identical in morphology for propulsion. Although fossils of these Mesozoic marine reptiles have been known for more than two centuries, the function and dynamics of their tandem-flipper propulsion system has always been unclear and controversial....

Thepreservationofthewingmembraneofpterosaursisverypoorandtheavailablefos- sil evidence does not allow its properties to be reconstructed. In contrast, the fossil record for the wing bones is relatively good and the advent of CT scanning has made it possible to build high- fidelity structural models of the wing spar. The bending strength of the wing...

Feathers have been evolving for more than 130 million years under selection pressures to become light, stiff and strong. However, a detailed investigation into their material structure (and properties) is still lacking. Previously, using nanoindentation and μCT, we have shown that feather shafts are fibrous laminar composites and that their structu...

Total body mass (TBM) is known to be related to a number of different osteological features in vertebrates, including limb element measurements and total skeletal mass. The relationship between skeletal mass and TBM in birds has been suggested as a way of estimating the latter in cases where only the skeleton is known (e.g., fossils). This relation...

Fundamental allometry dictates that there must be an upper limit to the size of flying vertebrates. The largest extant birds are around 3m in wingspan and 15kg in weight. Fossil birds may have reached 7m wingspan and weighed as much as 70kg, but they are dwarfed by the giant pterosaurs - 250kg late cretaceous azhdarchids with wing spans of more tha...

The reconstruction of any fossil animal is fraught with many uncertainties, which in the case of pterosaurs include the problematic phylogenetic bracketing and the very limited soft tissue preservation. Fortunately the record for these animals does include some excellently preserved three-dimensional fossil bones that, since the advent of CT scanni...

Living in water imposes severe constraints on the evolution of the vertebrate body. As a result of these constraints, numerous extant and extinct aquatic vertebrate groups evolved convergent osteological and soft-tissue adaptations. However, one important suite of adaptations is still poorly understood: dermal cover morphologies and how they influe...

Flight feathers have evolved under selective pressures to be sufficiently light and strong enough to cope with the stresses of flight. The feather shaft (rachis) must resist these stresses and is fundamental to this mode of locomotion. Relatively little work has been done on rachis morphology, especially from a mechanical perspective and never at t...

Cretaceous pterosaurs (azhdarchids, pteranodontids) are well known for giant wing spans, sometimes up to 10-12 metres: the size of small aircraft. Had these pterosaurs evolved to be as big as possible and was there a limit to their flight capabilities? Here, we present an analysis using aerodynamic design principles to determine the factors limitin...

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The evolution of avian flight is contentious and while it is now well established that modern birds are descended from theropod dinosaurs and that the presence of feathers predates the ability to fly, the process of transition from feathered, ground based dinosaurs to their feathered, flight capable descendants is less clear. While the evolutionary...

The diverse cartilaginous fish lineage, Batoidea (rays, skates, and allies), sister taxon to sharks, comprises a huge range of morphological diversity which to date remains unquantified and unexplained in terms of evolution or locomotor style. A recent molecular phylogeny has enabled us to confidently assess broadscale aspects of morphology across...

Air Space Proportion (ASP) is a measure of how much air is present within a bone, which allows for a quantifiable comparison of pneumaticity between specimens and species. Measured from zero to one, higher ASP means more air and less bone. Conventionally, it is estimated from measurements of the internal and external bone diameter, or by analyzing...

Pterosaurs have a substantially reduced trabecular network, consisting of fewer well-defined and enlarged struts, rather than the spongy network of fine, numerous trabeculae found in the cancellous bone of most other vertebrates. This reduction has been considered highly functional, associated with reduction in skeletal mass to produce a framework...

Understanding the aerodynamic performance of feathered, non-avialan dinosaurs is critical to reconstructing the evolution of bird flight. Here we show that the Early Cretaceous five-winged paravian Microraptor is most stable when gliding at high-lift coefficients (low lift/drag ratios). Wind tunnel experiments and flight simulations show that susta...

Air Space Proportion (ASP) is a measure of how much air is present within a bone, whichallows for quantifiable comparison of pneumaticity between specimens and species.Measured from zero to one, higher ASP means more air and less bone. Conventionally, it is estimated from measurements of the internal and external bone diameter. Thus far,very little...

Body mass estimation in extinct animals can provide information about ecology and biomechanics of the animal and is vital for flying animals as it determines its ability to take off, land, and indeed, fly. However, existing mass estimation methods for pterosaurs produce a wide range of values, especially in the larger animals. This hinders our unde...

The primary feathers of birds are subject to cyclical forces in flight causing their shafts (rachises) to bend. The amount the feathers deflect during flight is dependent upon the flexural stiffness of the rachises. By quantifying scaling relationships between body mass and feather linear dimensions in a large data set of living birds, we show that...

Animals that fly must be able to do so over a huge range of aerodynamic conditions, determined by weather, wind speed and the nature of their environment. No single parameter can be used to determine-let alone measure-optimum flight performance as it relates to wing shape. Reconstructing the wings of the extinct pterosaurs has therefore proved espe...

Models are a principal tool of modern science. By definition, and in practice, models are not literal representations of reality but provide simplifications or substitutes of the events, scenarios or behaviours that are being studied or predicted. All models make assumptions, and palaeontological models in particular require additional assumptions...

The flight of pterosaurs and the extreme sizes of some taxa have long perplexed evolutionary biologists. Past reconstructions of flight capability were handicapped by the available aerodynamic data, which was unrepresentative of possible pterosaur wing profiles. I report wind tunnel tests on a range of possible pterosaur wing sections and quantify...

This paper addresses the material boat culture of Vietnam both in its current context and more specifically through an assessment of how the boats of Vietnam have been studied in the past. It presents a comprehensive summary of past publications describing the construction, use and variety of boats in the region, from the earliest volumes to modern...

Scholars in rhetoric are increasingly attentive to the power of places and spaces to shape rhetorical performance. This article takes up the connection between ethos and location identified by several recent scholars, arguing that affiliation with and representation of material environments plays a crucial role in ethos. Ethos strategies are furthe...

The most cited work (by far) to provide safety factor estimates for the wing bones of flying vertebrates is inaccurate. Kirkpatrick ([Kirkpatrick, 1994][1]) presented extremely low measurements for the material properties of wing bones and anomalous estimates of applied loading that deflate

Article that addresses the variety in boat construction in the context of Bangladesh.

Pterosaurs, flying reptiles from the Mesozoic, had wing membranes that were supported by their arm bones and a super-elongate fourth finger. Associated with the wing, pterosaurs also possessed a unique wrist bone--the pteroid--that functioned to support the forward part of the membrane in front of the leading edge, the propatagium. Pteroid shape va...

Perhaps the most iconic of pterosaurs is the Late Cretaceous Pteranodon, known for its large wing span of up to 5.6 m or more and a remarkable long bony crest at the back of the head. The function of this crest has been the subject of much controversy, having been interpreted as an aerodynamically beneficial structure, perhaps acting as an airbrake...

Weatherliness is widely considered to have been an important ability for ancient sailing vessels, yet little firm experimental or theoretical data on the matter is available. However, by drawing on a variety of sources of model-test data and trials of full-scale replicas, it is possible to establish a general picture of what might have been possibl...

The balance of sailing vessels makes an important contribution to sailing characteristics, but its measurement is far from trivial. Traditionally, balance has been determined from the geometric centres of hulls and sails, but experimental results show that this approach is highly inaccurate. Designers overcome this difficulty by the use of a heuris...

  The Kuehneosauridae (Late Triassic, Britain, USA) had remarkable adaptations, most notably their elongate mid-dorsal ribs that were presumably covered with a skin membrane in life. These lateral ‘wings’ have always been linked with some form of gliding adaptation, but quantitative studies have been limited. Here, we provide a thorough aerodynamic...

Written in non-technical language, this book sets new standards for the documentation of water transport, and introduces styles of boat-building which are unlikely to be found outside the sub-Continent. A fascinating read for anyone intererested in boats or the South Asian way of life, as well as ethnographers, and maritime archaeolgists and histor...

The country boats of Bangladesh provide a vital transportation network in a country of waterways and regular flooding. Traditionally they have relied exclusively on renewable energy inputs for their motive power. In recent years they have suffered severe economic decline due to competition from trucks and buses running on new road systems. This dec...

For certain commercial sail projects, particularly those in parts of the developing world, there are very good reasons for using soft sail rigs. However, apart from the Bermudian rig, which has been developed for yacht racing, very little is known of the performance of different rigs.The direct measurement of sailing rig performance is a very diffi...