Pedal proportions of Poposaurus gracilis: convergence and divergence in the feet of archosaurs

The crocodile-line basal suchian Poposaurus gracilis had body proportions suggesting that it was an erect, bipedal form like many dinosaurs, prompting questions of whether its pedal proportions, and the shape of its footprint, would likewise "mimic" those of bipedal dinosaurs. We addressed these questions through a comparison of phalangeal, digital, and metatarsal proportions of Poposaurus with those of extinct and extant crocodile-line archosaurs, obligate or facultatively bipedal non-avian dinosaurs, and ground birds of several clades, as well as a comparison of the footprint reconstructed from the foot skeleton of Poposaurus with known early Mesozoic archosaurian ichnotaxa. Bivariate and multivariate analyses of phalangeal and digital dimensions showed numerous instances of convergence in pedal morphology among disparate archosaurian clades. Overall, the foot of Poposaurus is indeed more like that of bipedal dinosaurs than other archosaur groups, but is not exactly like the foot of any particular bipedal dinosaur clade. Poposaurus likely had a digitigrade stance, and its footprint shape could have resembled grallatorid ichnotaxa, unless digit I of the foot of Poposaurus commonly left an impression.

Tyrant dinosaur evolution tracks the rise and fall of Late Cretaceous oceans

The Late Cretaceous (∼95–66 million years ago) western North American landmass of Laramidia displayed heightened non-marine vertebrate diversity and intracontinental regionalism relative to other latest Cretaceous Laurasian ecosystems. Processes generating these patterns during this interval remain poorly understood despite their presumed role in the diversification of many clades. Tyrannosauridae, a clade of large-bodied theropod dinosaurs restricted to the Late Cretaceous of Laramidia and Asia, represents an ideal group for investigating Laramidian patterns of evolution. We use new tyrannosaurid discoveries from Utah—including a new taxon which represents the geologically oldest member of the clade—to investigate the evolution and biogeography of Tyrannosauridae. These data suggest a Laramidian origin for Tyrannosauridae, and implicate sea-level related controls in the isolation, diversification, and dispersal of this and many other Late Cretaceous vertebrate clades.

Euoplocephalus tutus and the diversity of ankylosaurid dinosaurs in the Late Cretaceous of Alberta, Canada, and Montana, USA

Few ankylosaurs are known from more than a single specimen, but the ankylosaurid Euoplocephalus tutus (from the Late Cretaceous of Alberta, Canada and Montana, USA) is represented by dozens of skulls and partial skeletons, and is therefore an important taxon for understanding intraspecific variation in ankylosaurs. Euoplocephalus is unusual compared to other dinosaurs from the Late Cretaceous of Alberta because it is recognized from the Dinosaur Park, Horseshoe Canyon, and Two Medicine formations. A comprehensive review of material attributed to Euoplocephalus finds support for the resurrection of its purported synonyms Anodontosaurus lambei and Scolosaurus cutleri, and the previously resurrected Dyoplosaurus acutosquameus. Anodontosaurus is found primarily in the Horseshoe Canyon Formation of Alberta and is characterized by ornamentation posterior to the orbits and on the first cervical half ring, and wide, triangular knob osteoderms. Euoplocephalus is primarily found in Megaherbivore Assemblage Zone 1 in the Dinosaur Park Formation of Alberta and is characterized by the absence of ornamentation posterior to the orbits and on the first cervical half ring, and keeled medial osteoderms on the first cervical half ring. Scolosaurus is found primarily in the Two Medicine Formation of Montana (although the holotype is from Dinosaur Provincial Park), and is characterized by long, back-swept squamosal horns, ornamentation posterior to the orbit, and low medial osteoderms on the first cervical half ring; Oohkotokia horneri is morphologically indistinguishable from Scolosaurus cutleri. Dyoplosaurus was previously differentiated from Euoplocephalus sensu lato by the morphology of the pelvis and pes, and these features also differentiate Dyoplosaurus from Anodontosaurus and Scolosaurus; a narrow tail club knob is probably also characteristic for Dyoplosaurus.

Piscivory in the feathered dinosaur Microraptor

The largest specimen of the four-winged dromaeosaurid dinosaur Microraptor gui includes preserved gut contents. Previous reports of gut contents and considerations of functional morphology have indicated that Microraptor hunted in an arboreal environment. The new specimen demonstrates that this was not strictly the case, and offers unique insights into the ecology of nonavian dinosaurs early in the evolution of flight. The preserved gut contents are composed of teleost fish remains. Several morphological adaptations of Microraptor are identified as consistent with a partially piscivorous diet, including dentition with reduced serrations and forward projecting teeth on the anterior of the dentary. The feeding habits of Microraptor can now be understood better than that of any other carnivorous nonavian dinosaur, and Microraptor appears to have been an opportunistic and generalist feeder, able to exploit the most common prey in both the arboreal and aquatic microhabitats of the Early Cretaceous Jehol ecosystem.

An ornithomimid (Dinosauria) bonebed from the Late Cretaceous of Alberta, with implications for the behavior, classification, and stratigraphy of North American ornithomimids

Bonebeds can provide a wealth of anatomical, taphonomic, and ontogenetic information about the specimens preserved within them, and can provide evidence for inferred behavior. The material described here represents the first known bonebed of ornithomimids in North America, and the fourth record of an ornithomimosaur bonebed in the world. Partial skeletons representing three individuals are preserved in this assemblage, each comprising primarily portions of the posterior postcrania (pelvis, hind limbs and tail). All three individuals are morphologically similar, although one is larger in overall size. Given the stratigraphic position of the site, and the morphology of the postcrania, the preserved material represents a taxon from the clade containing Ornithomimus and Struthiomimus. Pedal ungual morphology is examined and found to be too variable to be useful in distinguishing these species taxonomically. This site provides additional evidence of gregarious behavior in ornithomimids and the first probable record of that behavior in North American forms.

Histological variability in fossil and recent alligatoroid osteoderms: systematic and functional implications

Statements about morphological variation in extinct taxa often suffer from insufficient sampling that can be remedied by taking advantage of larger sample sizes provided by related, extant taxa. This analysis quantitatively and qualitatively examines histological and morphological variation of osteoderms from extant and extinct alligatoroid specimens. Statistically significant differences were correlated with changes in osteoderm size and shape. These differences are independent of position on the body, taxonomy, or evolution. Histological variation in alligatoroid osteoderms is due to morphological constraints on the elements themselves, and not taxonomic differences. This has implications for the recognition of histological characters in the osteoderms of extinct archosaur groups that lack extant representatives.

Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications

Oviraptorids are a group of specialized non-avian theropod dinosaurs that were generally one to 8 m in body length. New specimens of baby oviraptorids from the Late Cretaceous of Henan Province are some of the smallest individuals known. They include diagnostic characters such as the relative position of the antorbital fenestra and the external naris, distinct opening in the premaxilla anteroventral to the external naris, antorbital fossa partly bordered by premaxilla posterodorsally, lacrimal process of premaxilla does not contact the anterodorsal process of the lacrimal, parietal almost as long as frontal; in dorsal view, posterior margin forms a straight line between the postzygapophyses in each of the fourth and fifth cervicals; femur longer than ilium. They also elucidate the ontogenetic processes of oviraptorids, including fusion of cranial elements and changes in relative body proportions. Hind limb proportions are constant in oviraptorids, regardless of absolute body size or ontogenetic stage. This suggests a sedentary lifestyle that did not involve the pursuit of similar-sized prey. The functional implications for bite force and therefore dietary preferences are better understood through the study of such small animals. The comparison of the measurements of 115 skeletons indicates that oviraptorids maintain their hind limb proportions regardless of ontogenetic stage or absolute size, which is a pattern seen more commonly in herbivores than in carnivores. This may weakly support the hypothesis that oviraptorids are herbivores rather than active carnivores.

Abdominal contents from two large early cretaceous compsognathids (Dinosauria: Theropoda) demonstrate feeding on confuciusornithids and dromaeosaurids

Two skeletons of the large compsognathid Sinocalliopteryx gigas include intact abdominal contents. Both specimens come from the Jianshangou Beds of the lower Yixian Formation (Neocomian), Liaoning, China. The holotype of S. gigas preserves a partial dromaeosaurid leg in the abdominal cavity, here attributed to Sinornithosaurus. A second, newly-discovered specimen preserves the remains of at least two individuals of the primitive avialan, Confuciusornis sanctus, in addition to acid-etched bones from a possible ornithischian. Although it cannot be stated whether such prey items were scavenged or actively hunted, the presence of two Confuciusornis in a grossly similar state of digestion suggests they were consumed in rapid succession. Given the lack of clear arboreal adaptations in Sinocalliopteryx, we suggest it may have been an adept stealth hunter.

New specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia

Two new specimens of the oviraptorid theropod Nemegtomaia barsboldi from the Nemegt Basin of southern Mongolia are described. Specimen MPC-D 107/15 was collected from the upper beds of the Baruungoyot Formation (Campanian-Maastrichtian), and is a nest of eggs with the skeleton of the assumed parent of Nemegtomaia on top in brooding position. Much of the skeleton was damaged by colonies of dermestid coleopterans prior to its complete burial. However, diagnostic characters are recovered from the parts preserved, including the skull, partial forelimbs (including the left hand), legs, and distal portions of both feet. Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs. The second new specimen, MPC-D 107/16, was collected a few kilometers to the east in basal deposits of the Nemegt Formation, and includes both hands and femora of a smaller Nemegtomaia individual. The two formations and their diverse fossil assemblages have been considered to represent sequential time periods and different environments, but data presented here indicate partial overlap across the Baruungoyot-Nemegt transition. All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments. However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies.

Dinosaur speed demon: the caudal musculature of Carnotaurus sastrei and implications for the evolution of South American abelisaurids

In the South American abelisaurids Carnotaurus sastrei, Aucasaurus garridoi, and, to a lesser extent Skorpiovenator bustingorryi, the anterior caudal ribs project at a high dorsolateral inclination and have interlocking lateral tips. This unique morphology facilitated the expansion of the caudal hypaxial musculature at the expense of the epaxial musculature. Distinct ridges on the ventrolateral surfaces of the caudal ribs of Aucasaurus garridoi are interpreted as attachment scars from the intra caudofemoralis/ilio-ischiocaudalis septa, and confirm that the M. caudofemoralis of advanced South American abelisaurids originated from a portion of the caudal ribs. Digital muscle models indicate that, relative to its overall body size, Carnotaurus sastrei had a substantially larger M. caudofemoralis than any other theropod yet studied. In most non-avian theropods, as in many extant sauropsids, the M. caudofemoralis served as the primary femoral retractor muscle during the locomotive power stroke. This large investment in the M. caudofemoralis suggests that Carnotaurus sastrei had the potential for great cursorial abilities, particularly short-burst sprinting. However, the tightly interlocking morphology of the anterior caudal vertebrae implies a reduced ability to make tight turns. Examination of these vertebral traits in evolutionary context reveals a progressive sequence of increasing caudofemoral mass and tail rigidity among the Abelisauridae of South America.

The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction

Internal cranial anatomy is a challenging area to study in fossilized skulls because of small sample sizes and varied post-mortem preservational alterations. This difficulty has led to the lack of correspondence between results obtained from direct osteological observation and from more indirect reconstruction methods. This paper presents corroborating evidence from direct osteological observation and from reconstruction based on computed X-ray tomography (CT) on the internal cranial anatomy of the ankylosaurid dinosaur Euoplocephalus tutus. A remarkable specimen of Euoplocephalus preserves rarely observed internal cranial structures such as vascular impressions in the nasal cavity, olfactory turbinates and possible impressions of conchae. Comparison with fossils and CT models of other taxa and other Euoplocephalus specimens adds osteological evidence for the previously reconstructed nasal cavity in this dinosaur and revises the previously described braincase morphology. A new interpretation of the ethmoidal homology identifies a mesethmoid, sphenethmoid and ectethmoid. These ethmoidal ossifications are continuous with the mineralized walls of the nasal cavity. The location of the olfactory fenestra provides further evidence that the olfactory regions of the nasal cavity are pushed to the sides of the main airway. This implies that the function of the vascular impressions in the nasal cavity and the looping of the cavity are not related to olfaction. A byproduct of the elongate, looping airway is a dramatic increase in surface area of the nasal respiratory mucosa, which in extant species has been linked to heat and water balance. A role in vocalization as a resonating chamber is another possible function of the looping and elongation of the nasal cavity. Olfaction remains as a possible function for the enlarged olfactory region, suggesting that multiple functions account for different parts of the ankylosaurid nasal cavity that underwent substantial modification. Cranial endocasts show negligible variation within Euoplocephalus, which lends some confidence to interspecific comparisons of endocranial morphology.

A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber

The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution.

Hemodynamic effects of fenofibrate and coenzyme Q10 in type 2 diabetic subjects with left ventricular diastolic dysfunction

OBJECTIVE

To investigate the effects of fenofibrate and coenzyme Q(10) (CoQ) on diastolic function, ambulatory blood pressure (ABP), and heart rate (HR) in type 2 diabetic subjects with left ventricular diastolic dysfunction (LVDD).

RESEARCH DESIGN AND METHODS

We randomized, double-blind, 74 subjects to fenofibrate 160 mg daily, CoQ 200 mg daily, fenofibrate 160 mg plus CoQ 200 mg daily, or matching placebo for 6 months. Echocardiography (including tissue Doppler imaging) and 24-h ABP and HR monitoring were performed pre- and postintervention.

RESULTS

Neither fenofibrate nor CoQ, alone or in combination, altered early diastolic mitral annular myocardial relaxation velocity (E'), early-to-late mitral inflow velocity ratio (E/A), deceleration time, isovolumic relaxation time, or the ratio of early mitral flow velocity to early diastolic mitral annular myocardial relaxation velocity (E/E') compared with placebo (P > 0.05). Fenofibrate and CoQ interactively (P = 0.001) lowered 24-h systolic blood pressure (-3.4 +/- 0.09 mmHg, P = 0.010), with a prominent nocturnal effect (-5.7 +/- 1.5 mmHg, P = 0.006). Fenofibrate (-1.3 +/- 0.5 mmHg, P = 0.013) and CoQ (-2.2 +/- 0.5 mmHg, P < 0.001) independently lowered 24-h diastolic blood pressure. Fenofibrate reduced 24-h HR (-3.3 +/- 0.5 beats/min, P < 0.001), but CoQ had no effect on HR.

CONCLUSIONS

In type 2 diabetic subjects with LVDD, neither fenofibrate nor CoQ, alone or in combination, improved diastolic function significantly. However, fenofibrate and CoQ independently and interactively lowered 24-h blood pressure, and fenofibrate alone reduced 24-h HR.

Tyrannosaur life tables: an example of nonavian dinosaur population biology

The size and age structures for four assemblages of North American tyrannosaurs-Albertosaurus, Tyrannosaurus, Gorgosaurus, and Daspletosaurus-reveal a pronounced, bootstrap-supported pattern of age-specific mortality characterized by relatively high juvenile survivorship and increased mortality at midlife and near the maximum life span. Such patterns are common today in wild populations of long-lived birds and mammals. Factors such as predation and entrance into the breeding population may have influenced tyrannosaur survivorship. This survivorship pattern can explain the rarity of juvenile specimens in museum collections.

Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs

How evolutionary changes in body size are brought about by variance in developmental timing and/or growth rates (also known as heterochrony) is a topic of considerable interest in evolutionary biology. In particular, extreme size change leading to gigantism occurred within the dinosaurs on multiple occasions. Whether this change was brought about by accelerated growth, delayed maturity or a combination of both processes is unknown. A better understanding of relationships between non-avian dinosaur groups and the newfound capacity to reconstruct their growth curves make it possible to address these questions quantitatively. Here we study growth patterns within the Tyrannosauridae, the best known group of large carnivorous dinosaurs, and determine the developmental means by which Tyrannosaurus rex, weighing 5,000 kg and more, grew to be one of the most enormous terrestrial carnivorous animals ever. T. rex had a maximal growth rate of 2.1 kg d(-1), reached skeletal maturity in two decades and lived for up to 28 years. T. rex's great stature was primarily attained by accelerating growth rates beyond that of its closest relatives.

Telehealth and the diagnosis and management of cardiac disease

The financial and personal burden of chronic cardiac disease is high. Costs are likely to increase over the next few decades. Promising applications of telehealth have appeared in the diagnosis and management of cardiac disease and there are indications that telehealth services can improve the management of chronic cardiac disease as well as extend services to remote and rural populations. Telehealth has been applied to the capture of symptoms of cardiac disease with electrocardiography and echocardiography, to the management and rehabilitation of recently discharged patients, and in peer-to-peer consultation where remote expertise can facilitate diagnosis. Telehealth promises cost reductions in service delivery, although there is a need for properly controlled cost-effectiveness trials to underpin telehealth with a firm evidence base.

Hypothalamic paraventricular nucleus injections of urocortin alter food intake and respiratory quotient

Corticotropin releasing hormone (CRH) acts on the central nervous system to alter energy balance and influence both food intake and sympathetically-mediated thermogenesis. CRH is also reported to inhibit food intake in several models of hyperphagia including neuropeptide Y (NPY)-induced eating. The recently identified CRH-related peptide, urocortin (UCN), also binds with high affinity to CRH receptor subtypes and decreases food intake in food-deprived and non-deprived rats. The present experiment characterized further the feeding and metabolic effects of UCN by examining its impact after direct injections into the paraventricular nucleus (PVN) of the hypothalamus. In feeding tests (n=8), UCN (50-200 pmol) was injected into the PVN at the onset of the dark cycle and food intake was measured 1, 2 and 4 h postinjection. In separate rats (n=8), the metabolic effects of UCN were monitored using an open circuit calorimeter which measured oxygen consumption (V(O2)) and carbon dioxide production (V(CO2)). Respiratory quotient (RQ) was calculated as V(CO2)/V(O2). UCN suppressed feeding at all times studied and reliably decreased RQ within 30 min of infusion. Additional work examined the effect of UCN (50-100 pmol) pretreatment on the feeding and metabolic effects of NPY. NPY, injected at the start of the dark period, reliably increased 2 h food intake. This effect was blocked by PVN UCN administration. Similarly, UCN blocked the increase in RQ elicited by NPY alone. These results suggest that UCN-sensitive mechanisms within the PVN may modulate food intake and energy substrate utilization, possibly through an interaction with hypothalamic NPY.

Palaeontology. The beaks of ostrich dinosaurs

Primitive ornithomimids, a ubiquitous group of specialized Cretaceous dinosaurs nested within a clade of predominantly carnivorous theropods, are known to have had teeth, whereas derived ornithomimids had an edentulous beak, which has prompted speculation about their dietary habits. Here we describe two new ornithomimid specimens in which soft-tissue structures of the beak have been preserved. These creatures probably used their beaks to strain food sediment in an aqueous environment, rather than for predation on large animals.

Forensic palaeontology: The Archaeoraptor forgery

The Archaeoraptor fossil was announced as a 'missing link' and purported to be possibly the best evidence since Archaeopteryx that birds did, in fact, evolve from certain types of carnivorous dinosaur. It reportedly came from Early Cretaceous beds of China that have produced other spectacular fossils transitional between birds and extinct non-avian dinosaurs. But Archaeoraptor was revealed to be a forgery in which bones of a primitive bird and a non-flying dromaeosaurid dinosaur had been combined. Here we use high-resolution X-ray computed tomography (CT) to determine the nature and extent of the forgery, as well as how it was built, by imaging the fracture pattern and distribution of materials through the entire specimen.

Posterodorsal amygdala lesions reduce feeding stimulated by 8-OH-DPAT

Injections of the serotonin (5-HT)(1A) agonist, 8-hydroxy-2(di-n-propylamino)tetralin, (8-OH-DPAT), either systemically or into the midbrain raphe nuclei, elicit food intake in otherwise satiated rats. Lesions of the paraventricular nucleus of the hypothalamus are well known for producing long-term overeating, but past research has excluded this site as a potential locus for short-term 8-OH-DPAT feeding effects. More recent work shows that small lesions of the posterodorsal amygdala (PDA) elicit overeating in their own right. Since this and related regions of the amygdala receive 5-HT innervations from the dorsal raphe nucleus (DRN), we determined if PDA lesions might alter feeding after injecting 8-OH-DPAT into this midbrain region. Adult female rats received either bilateral electrolytic lesions of the PDA or sham lesions. After recording weight gains for over 1 month, all rats were implanted with DRN cannulae, then randomly tested every 3-4 days for 1 h intake of standard lab chow after 0, 0.4, 0.8 or 1.6 nmol injections of 8-OH-DPAT. Additional 90 min measures of intake were also made after 0 vs. 250 microg (760 nmol) 8-OH-DPAT s.c. At the two highest DRN doses tested, lesioned rats showed 50% less intake compared to shams. A similar profile emerged after the single s.c. dose. These results suggest that the PDA may be an important locus at which reduced release of endogenous 5-HT stimulates feeding. Alternatively, the PDA may represent part of a larger brain circuit whose integrity is necessary for eliciting intake in response to a variety of feeding stimuli.