Using your head - cranial steering in pterosaurs.

The vast majority of pterosaurs are characterized by relatively large, elongate heads that are often adorned with large, elaborate crests. Projecting out in front of the body, these large heads and any crests must have had an aerodynamic effect. The working hypothesis of the present study is that these oversized heads were used to control the left-right motions of the body during flight. Using digital models of eight non-pterodactyloids ("rhamphorhyncoids") and ten pterodactyloids, the turning moments associated with the head + neck show a close and consistent correspondence with the rotational inertia of the whole body about a vertical axis in both groups, supporting the idea of a functional relationship. Turning moments come from calculating the lateral area of the head (plus any crests) and determining the associated lift (aerodynamic force) as a function of flight speed, with flight speeds being based on body mass. Rotational inertias were calculated from the three-dimensional mass distribution of the axial body, the limbs, and the flight membranes. The close correlation between turning moment and rotational inertia was used to revise the life restorations of two pterosaurs and to infer relatively lower flight speeds in another two.

Growth constraints set an upper limit to theropod dinosaur body size.

Despite nearly 200 years of scientific collecting and study, none of the extinct, bipedal, predatory, theropod dinosaurs have been reliably shown to exceed 12 m in length. Using digital 3D models of theropods with lengths spanning 80 cm to 12 m, their body masses were found to scale to the 3.5 power of body lengths. The lateral area of the pelvis and the cross-sectional area of the tail base of these animals corresponds to the cross-sectional areas of key muscle groups important for balance and locomotion, and both scale to the 2.4 power of body length. Body accelerations in the lateral and forward directions are, using F = ma, given by dividing muscle area (force proxy) by body mass. Plotting these acceleration estimates against body length shows them to decrease exponentially. The largest theropods with body lengths of 10-12 m have less than 10% of the acceleration capacity of the smaller forms. The distinct lack of fossil remains of theropods demonstrably longer than 12 m suggests that the theropod body plan had an upper size limit based on a minimum acceleration threshold. Rotational inertia of the theropod body was found to be proportional to body length raised to the 5.5 power, and with increasing length, the capacity for agility would rapidly diminish. The tight relationship between theropod pelvic area and body length allows for the estimation of body lengths of specimens lacking complete axial skeletons, and this is done for four, large, well-preserved pelves.

Structural Emergence in Particle Dispersions.

Particle dispersions, such as pigment-based inks, comprise weakly bound, milled nanoparticles. The properties of these pigments depend on both their chemical composition and a rather complex structural hierarchy which emerges from these dispersions. The emergence of structure under semidilute conditions is related to the structure of the dilute particles, the particle spacing (mesh size), processing history, and the interaction potential. Kinetic simulations could predict such emergence using these input parameters. In this paper, organic pigments are studied as an example of the importance of emergent structure to predict properties such as brilliance and opacity. Organic pigments are used to impart color to commercial inks, plastics, coatings, and cosmetics. In many cases, dilute pigments are mass fractal structures consisting of aggregated nanoparticles held together by weak van der Waals forces. In water, surfactant is added to create a pigment dispersion (an ink). The final properties of a pigment emerge from a complex interplay between aggregation and dispersion of aggregates as a function of concentration. Samples of the organic pigment yellow 14, PY14, were milled to four primary particle sizes to study the effect on structural emergence. The interaction between surfactant-stabilized PY14 aggregates in an aqueous medium was quantified by the second virial coefficient, A2, which reflects long-range interactions. The degree of aggregation is associated with short-range attractive interactions between primary particles. In this series of pigments, the degree of aggregation increases dramatically with reduction in primary particle size. Concurrently, the second-order virial coefficient, A2, increases reflecting stronger long-range repulsive interactions with particle size. Structural emergence can be understood through the percolation concentration and the filler mesh size. A2 is translated into a repulsive interaction potential for use in dissipative particle dynamics simulations to enable predictive modeling. This description of the interactions between dispersed pigment aggregates allows for a more scientific and predictive approach to understand structural emergence.

What drove reversions to quadrupedality in ornithischian dinosaurs? Testing hypotheses using centre of mass modelling.

The exceptionally rare transition to quadrupedalism from bipedal ancestors occurred on three independent occasions in ornithischian dinosaurs. The possible driving forces behind these transitions remain elusive, but several hypotheses-including the development of dermal armour and the expansion of head size and cranial ornamentation-have been proposed to account for this major shift in stance. We modelled the position of the centre of mass (CoM) in several exemplar ornithischian taxa and demonstrate that the anterior shifts in CoM position associated with the development of an enlarged skull ornamented with horns and frills for display/defence may have been one of the drivers promoting ceratopsian quadrupedality. A posterior shift in CoM position coincident with the development of extensive dermal armour in thyreophorans demonstrates this cannot have been a primary causative mechanism for quadrupedality in this clade. Quadrupedalism developed in response to different selective pressures in each ornithischian lineage, indicating different evolutionary pathways to convergent quadrupedal morphology.

Diving dinosaurs? Caveats on the use of bone compactness and pFDA for inferring lifestyle.

The lifestyle of spinosaurid dinosaurs has been a topic of lively debate ever since the unveiling of important new skeletal parts for Spinosaurus aegyptiacus in 2014 and 2020. Disparate lifestyles for this taxon have been proposed in the literature; some have argued that it was semiaquatic to varying degrees, hunting fish from the margins of water bodies, or perhaps while wading or swimming on the surface; others suggest that it was a fully aquatic underwater pursuit predator. The various proposals are based on equally disparate lines of evidence. A recent study by Fabbri and coworkers sought to resolve this matter by applying the statistical method of phylogenetic flexible discriminant analysis to femur and rib bone diameters and a bone microanatomy metric called global bone compactness. From their statistical analyses of datasets based on a wide range of extant and extinct taxa, they concluded that two spinosaurid dinosaurs (S. aegyptiacus, Baryonyx walkeri) were fully submerged "subaqueous foragers," whereas a third spinosaurid (Suchomimus tenerensis) remained a terrestrial predator. We performed a thorough reexamination of the datasets, analyses, and methodological assumptions on which those conclusions were based, which reveals substantial problems in each of these areas. In the datasets of exemplar taxa, we found unsupported categorization of taxon lifestyle, inconsistent inclusion and exclusion of taxa, and inappropriate choice of taxa and independent variables. We also explored the effects of uncontrolled sources of variation in estimates of bone compactness that arise from biological factors and measurement error. We found that the ability to draw quantitative conclusions is limited when taxa are represented by single data points with potentially large intrinsic variability. The results of our analysis of the statistical method show that it has low accuracy when applied to these datasets and that the data distributions do not meet fundamental assumptions of the method. These findings not only invalidate the conclusions of the particular analysis of Fabbri et al. but also have important implications for future quantitative uses of bone compactness and discriminant analysis in paleontology.

Assessment of serosurveys for H5N1.

BACKGROUND: It has been suggested that the true case-fatality rate of human H5N1 influenza infection is appreciably less than the figure of approximately 60% that is based on official World Health Organization (WHO)-confirmed case reports because asymptomatic cases may have been missed. A number of seroepidemiologic studies have been conducted in an attempt to identify such missed cases. METHODS: We conducted a comprehensive literature review of all English-language H5N1 human serology surveys with detailed attention to laboratory methodology used (including whether investigators used criteria set by the WHO to define positive cases), laboratory controls used, and the clades/genotypes involved. RESULTS: Twenty-nine studies were included in the analysis. Few reported using unexposed control groups and one-third did not apply WHO criteria. Of studies that used WHO criteria, only 4 found any seropositive results to clades/genotypes of H5N1 that are currently circulating. No studies reported seropositive results to the clade 2/genotype Z viruses that have spread throughout Eurasia and Africa. CONCLUSIONS: This review suggests that the frequency of positive H5 serology results is likely to be low; therefore, it is essential that future studies adhere to WHO criteria and include unexposed controls in their laboratory assays to limit the likelihood of false-positive results.

An Src-protein tyrosine kinase inhibitor to reduce cisplatin ototoxicity while preserving its antitumor effect.

Ototoxicity remains a major dose-limiting side effect of cisplatin. The current studies were carried out to evaluate the effectiveness of a novel Src-protein tyrosine kinase inhibitor in protecting the ear from cisplatin ototoxicity without compromising cisplatin's antitumor effects. The Src inhibitor has been shown to be effective in protecting the ear from noise-induced hearing loss. Three studies were carried out to determine whether this compound has otoprotective activity in rats treated with cisplatin. The first two studies used the Src inhibitor as a cotreatment with single doses of cisplatin in Fischer 344/NHsd rats and nude rats, respectively. Cochlear damage was assessed by auditory brainstem response threshold shifts and outer hair cell loss. The third study was carried out in nude rats with implanted HT-29 tumors, and the Src inhibitor was administered as a cotreatment with a lower dose of cisplatin. Cochlear damage and changes in tumor volume were assessed in the third study. In the first two studies, cotreatment with the Src inhibitor reduced cisplatin-induced hearing loss significantly. In the third study, little hearing loss was induced because of the use of a lower dose of cisplatin. However, cotreatment with the Src inhibitor did not exert a negative effect on cisplatin's slowing of tumor growth in the treated rats. The findings suggest that the Src inhibitor may provide an effective cotreatment with cisplatin to reduce cisplatin's ototoxicity, without compromising its antitumor capability.

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs.

The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.

Reduced T(H)1/T(H)17 CD4 T-cell numbers are associated with impaired purified protein derivative-specific cytokine responses in patients with HIV-1 infection.

BACKGROUND: In HIV-1-infected patients impaired IFN-γ responses to purified protein derivative (PPD) are associated with an increased risk of active tuberculosis. Tuberculosis antigen-specific cells are found in the T(H)1/T(H)17 subset of CD4 T cells, which support HIV-1 replication. Selective loss of T(H)1/T(H)17 cells in patients with HIV-1 infection might contribute to reduced tuberculosis-induced immune responses and an increased susceptibility to active tuberculosis. OBJECTIVES: We sought to investigate the association between T(H)1/T(H)17 cells and PPD-specific cytokine responses in HIV-1-infected patients. METHODS: A cross-sectional study was performed on healthy control subjects, HIV-1-infected patients receiving successful antiretroviral therapy (ART(+)), and ART-naive HIV-1-infected patients (ART(-)). All patients studied had evidence of BCG vaccination. Four discrete CD4 T-cell subsets were assessed by flow cytometry: T(H)1/T(H)17 cells (CXCR3(+)CCR6(+)CCR4(-)), T(H)1 cells (CXCR3(+)CCR6(-)CCR4(-)), T(H)17 cells (CXCR3(-)CCR6(+)CCR4(+)), and T(H)2 cells (CXCR3(-)CCR6(-)CCR4(+)). IFN-γ and IL-2 PPD-specific cytokine responses were assessed in PBMCs by using the enzyme-linked immunospot assay. RESULTS: Twenty-nine healthy control subjects, 34 ART(+) patients, and 26 ART(-) patients were recruited. The number and frequency of T(H)1/T(H)17 and T(H)1/T(H)17 CCR5(+) CD4 T cells were significantly reduced in HIV-1-infected patients. IFN-γ and IL-2 PPD responses were significantly lower in ART(-) patients and were partially reconstituted with successful ART. Loss of T(H)1/T(H)17 CCR5(+) cells was associated with reduced IFN-γ and IL-2 PPD responses. CONCLUSIONS: Selective loss of T(H)1/T(H)17 cells may be a risk factor for the development of active tuberculosis in patients with HIV-1 infection and might be a useful biomarker in the development of tuberculosis vaccines.

Fluid dynamics, scaling laws and plesiosaur locomotion.

The evolutionary success of plesiosaurs has led to much attention regarding the dynamics of their locomotion. They exhibit identical tandem flippers, which is unique among all living and extinct species. However, these tandem flippers have been a source of debate regarding plesiosaurs' locomotion and behavior. Here we propose a new approach to studying plesiosaur locomotion based on universal scaling laws in fluid dynamics, which were used to estimate reduced frequency to characterize unsteadiness of an airfoil. It was found that, while the reduced frequency of plesiosaurs with high-aspect ratio flippers is similar to that of sea turtles, the most commonly used living analog, lower aspect ratio plesiosaurs were more similar in reduced frequency to penguins. This implies that plesiosaurs may have had large variations in agility among themselves, depending in particular on the specimen's flipper aspect ratio. While our results are consistent with the previous literature indicating a relationship between plesiosaur neck length and agility, our work supports broad and diverse analogies to living animals. Moreover, based on our results, cruising reduced frequency has some predictive value into manoeuvring behavior, rather than simply cruising behavior.

Spinosaurus is not an aquatic dinosaur.

A predominantly fish-eating diet was envisioned for the sail-backed theropod dinosaur Spinosaurus aegyptiacus when its elongate jaws with subconical teeth were unearthed a century ago in Egypt. Recent discovery of the high-spined tail of that skeleton, however, led to a bolder conjecture that S. aegyptiacus was the first fully aquatic dinosaur. The 'aquatic hypothesis' posits that S. aegyptiacus was a slow quadruped on land but a capable pursuit predator in coastal waters, powered by an expanded tail. We test these functional claims with skeletal and flesh models of S. aegyptiacus. We assembled a CT-based skeletal reconstruction based on the fossils, to which we added internal air and muscle to create a posable flesh model. That model shows that on land S. aegyptiacus was bipedal and in deep water was an unstable, slow-surface swimmer (<1 m/s) too buoyant to dive. Living reptiles with similar spine-supported sails over trunk and tail are used for display rather than aquatic propulsion, and nearly all extant secondary swimmers have reduced limbs and fleshy tail flukes. New fossils also show that Spinosaurus ranged far inland. Two stages are clarified in the evolution of Spinosaurus, which is best understood as a semiaquatic bipedal ambush piscivore that frequented the margins of coastal and inland waterways.

The role of research in viral disease eradication and elimination programs: lessons for malaria eradication.

By examining the role research has played in eradication or regional elimination initiatives for three viral diseases--smallpox, poliomyelitis, and measles--we derive nine cross-cutting lessons applicable to malaria eradication. In these initiatives, some types of research commenced as the programs began and proceeded in parallel. Basic laboratory, clinical, and field research all contributed notably to progress made in the viral programs. For each program, vaccine was the lynchpin intervention, but as the programs progressed, research was required to improve vaccine formulations, delivery methods, and immunization schedules. Surveillance was fundamental to all three programs, whilst polio eradication also required improved diagnostic methods to identify asymptomatic infections. Molecular characterization of pathogen isolates strengthened surveillance and allowed insights into the geographic source of infections and their spread. Anthropologic, sociologic, and behavioural research were needed to address cultural and religious beliefs to expand community acceptance. The last phases of elimination and eradication became increasingly difficult, as a nil incidence was approached. Any eradication initiative for malaria must incorporate flexible research agendas that can adapt to changing epidemiologic contingencies and allow planning for posteradication scenarios.

Postexposure treatment with a Src-PTK inhibitor in combination with N-l-acetyl cysteine to reduce noise-induced hearing loss.

Both the antioxidant, N-l-acetyl cysteine (NAC), and the Src inhibitor, KX1-004, have been used to protect the cochlea from hazardous noise. In order to extend our previous work on KX1-004 with noise exposure, the current studies were undertaken with two goals: (1) to test the effectiveness of NAC and KX1-004 in combination with one another when given in a protection paradigm, and (2) to test the NAC+KX1-004 combination in a postexposure rescue paradigm. The noise exposure for the first experiment consisted of a 4-kHz octave band of noise at 107 dB SPL for 2 hours. The combination of NAC and KX1-004 were administered either prior to the noise exposure or post exposure (rescue). The second experiment was undertaken to extend the findings of the first experiment's rescue paradigm. The 4 kHz octave band noise was delivered at 112 dB SPL for 1 hour, with the experimental drugs delivered only in a rescue paradigm. In Experiment 1, animals treated before the 2-hour noise exposure with the combination of NAC and KX1-004 had from 12 to 17 dB less permanent threshold shift when compared to control saline treated animals. Treatment in the rescue paradigm did not produce any reductions in threshold shift from the 2-hour exposure. In the second experiment, with the 1-hour noise, rescue with KX1-004 or KX1-004 plus NAC yielded small, but significant, reductions in threshold shift. There was no additional benefit from the combination of NAC and KX1-004 over KX1-004 by itself.

Dental microwear texture analysis along reptile tooth rows: complex variation with non-dietary variables.

Dental microwear texture analysis (DMTA) is a powerful technique for reconstructing the diets of extant and extinct taxa. Few studies have investigated intraspecific microwear differences along with tooth rows and the influence of endogenous non-dietary variables on texture characteristics. Sampling teeth that are minimally affected by non-dietary variables is vital for robust dietary reconstructions, especially for taxa with non-occlusal (non-chewing) dentitions as no standardized sampling strategies currently exist. Here, we apply DMTA to 13 species of extant reptile (crocodilians and monitor lizards) to investigate intraspecific microwear differences along with tooth rows and to explore the influence of three non-dietary variables on exhibited differences: (i) tooth position, (ii) mechanical advantage, and (iii) tooth aspect ratio. Five species exhibited intraspecific microwear differences. In several crocodilians, the distally positioned teeth exhibited the 'roughest' textures, and texture characteristics correlated with all non-dietary variables. By contrast, the mesial teeth of the roughneck monitor (Varanus rudicollis) exhibited the 'roughest' textures, and texture characteristics did not correlate with aspect ratio. These results are somewhat consistent with how reptiles preferentially use their teeth during feeding. We argue that DMTA has the potential to track mechanical and behavioural differences in tooth use which should be taken into consideration in future dietary reconstructions.

Maniraptoran pelvic musculature highlights evolutionary patterns in theropod locomotion on the line to birds.

Locomotion is a fundamental aspect of palaeobiology and often investigated by comparing osteological structures and proportions. Previous studies document a stepwise accumulation of avian-like features in theropod dinosaurs that accelerates in the clade Maniraptora. However, the soft tissues that influenced the skeleton offer another perspective on locomotory adaptations. Examination of the pelvis for osteological correlates of hind limb and tail musculature allowed reconstruction of primary locomotory muscles across theropods and their closest extant relatives. Additionally, the areas of pelvic muscle origins were quantified to measure relative differences within and between taxa, to compare morphological features associated with cursoriality, and offer insight into the evolution of locomotor modules. Locomotory inferences based on myology often corroborate those based on osteology, although they occasionally conflict and indicate greater complexity than previously appreciated. Maniraptoran pelvic musculature underscores previous studies noting the multifaceted nature of cursoriality and suggests that a more punctuated step in caudal decoupling occurred at or near the base of Maniraptora.

Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America.

The extremes of dinosaur body size have long fascinated scientists. The smallest (<1 m length) known dinosaurs are carnivorous saurischian theropods, and similarly diminutive herbivorous or omnivorous ornithischians (the other major group of dinosaurs) are unknown. We report a new ornithischian dinosaur, Fruitadens haagarorum, from the Late Jurassic of western North America that rivals the smallest theropods in size. The largest specimens of Fruitadens represent young adults in their fifth year of development and are estimated at just 65-75 cm in total body length and 0.5-0.75 kg body mass. They are thus the smallest known ornithischians. Fruitadens is a late-surviving member of the basal dinosaur clade Heterodontosauridae, and is the first member of this clade to be described from North America. The craniodental anatomy and diminutive body size of Fruitadens suggest that this taxon was an ecological generalist with an omnivorous diet, thus providing new insights into morphological and palaeoecological diversity within Dinosauria. Late-surviving (Late Jurassic and Early Cretaceous) heterodontosaurids are smaller and less ecologically specialized than Early (Late Triassic and Early Jurassic) heterodontosaurids, and this ecological generalization may account in part for the remarkable 100-million-year-long longevity of the clade.

Predicting the buoyancy, equilibrium and potential swimming ability of giraffes by computational analysis.

Giraffes (Giraffa camelopardalis) are often stated to be unable to swim, and while few observations supporting this have ever been offered, we sought to test the hypothesis that giraffes exhibited a body shape or density unsuited for locomotion in water. We assessed the floating capability of giraffes by simulating their buoyancy with a three-dimensional mathematical/computational model. A similar model of a horse (Equus caballus) was used as a control, and its floating behaviour replicates the observed orientations of immersed horses. The floating giraffe model has its neck sub-horizontal, and the animal would struggle to keep its head clear of the water surface. Using an isometrically scaled-down giraffe model with a total mass equal to that of the horse, the giraffe's proportionally larger limbs have much higher rotational inertias than do those of horses, and their wetted surface areas are 13.5% greater relative to that of the horse, thus making rapid swimming motions more strenuous. The mean density of the giraffe model (960 gm/l) is also higher than that of the horse (930 gm/l), and closer to that causing negative buoyancy (1000 gm/l). A swimming giraffe - forced into a posture where the neck is sub-horizontal and with a thorax that is pulled downwards by the large fore limbs - would not be able to move the neck and limbs synchronously as giraffes do when moving on land, possibly further hampering the animal's ability to move its limbs effectively underwater. We found that a full-sized, adult giraffe will become buoyant in water deeper than 2.8m. While it is not impossible for giraffes to swim, we speculate that they would perform poorly compared to other mammals and are hence likely to avoid swimming if possible.

Dietary palaeoecology of an Early Cretaceous armoured dinosaur (Ornithischia; Nodosauridae) based on floral analysis of stomach contents.

The exceptionally well-preserved holotype of the armoured dinosaur Borealopelta markmitchelli (Ornithischia; Nodosauridae) from the Early Cretaceous (Clearwater Formation) of northern Alberta preserves a distinct mass within the abdominal cavity. Fourteen independent criteria (including: co-allochthony, anatomical position, gastroliths) support the interpretation of this mass as ingested stomach contents-a cololite. Palynomorphs in the cololite are a subset of the more diverse external sample. Analysis of the cololite documents well-preserved plant material dominated by leaf tissue (88%), including intact sporangia, leaf cross-sections and cuticle, but also including stems, wood and charcoal. The leaf fraction is dominated (85%) by leptosporangiate ferns (subclass Polypodiidae), with low cycad-cycadophyte (3%) and trace conifer foliage. These data represent the most well-supported and detailed direct evidence of diet in an herbivorous dinosaur. Details of the dietary palaeoecology of this nodosaur are revealed, including: selective feeding on ferns; preferential ingestion of leptosporangiate ferns to the exclusion of Osmundaceae and eusporangiate ferns such as Marattiaceae; and incidental consumption of cycad-cycadophyte and conifer leaves. The presence of significant (6%) charcoal may represent the dietary use of recently burned conifer forest undergoing fern succession, early evidence of a fire succession ecology, as is associated with many modern large herbivores.

Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods.

SYNOPSIS: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. METHODS: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. RESULTS: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). IMPLICATIONS: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.