Placoderms.

For over 70 million years, during the Paleozoic, the placoderms (Greek for 'plated skin'), an extinct group of armoured fishes, were the most abundant and diverse vertebrates on our planet. Some of the first placoderm fossils discovered - such as Bothriolepis with its bone-covered pectoral fins - seemed so bizarre that they were thought to represent turtles or ancient beetles. All placoderms bear thick overlapping dermal plates around the head (called the 'head shield') and an area of the body covered in similar overlapping plates enveloping the pectoral to anal region (called the 'trunk-shield'). Placoderm fossils (Figure 1) are known from every continent on Earth ranging from the early Silurian (∼438 million years ago) to the end Devonian (∼359 million years ago) when they became extinct.

Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte.

The origin and early diversification of jawed vertebrates involved major changes to skeletal and soft anatomy. Skeletal transformations can be examined directly by studying fossil stem gnathostomes; however, preservation of soft anatomy is rare. We describe the only known example of a three-dimensionally mineralized heart, thick-walled stomach, and bilobed liver from arthrodire placoderms, stem gnathostomes from the Late Devonian Gogo Formation in Western Australia. The application of synchrotron and neutron microtomography to this material shows evidence of a flat S-shaped heart, which is well separated from the liver and other abdominal organs, and the absence of lungs. Arthrodires thus show the earliest phylogenetic evidence for repositioning of the gnathostome heart associated with the evolution of the complex neck region in jawed vertebrates.

Morphometric analysis of lungfish endocasts elucidates early dipnoan palaeoneurological evolution.

The lobe-finned fish, lungfish (Dipnoi, Sarcoptergii), have persisted for ~400 million years from the Devonian Period to present day. The evolution of their dermal skull and dentition is relatively well understood, but this is not the case for the central nervous system. While the brain has poor preservation potential and is not currently known in any fossil lungfish, substantial indirect information about it and associated structures (e.g. labyrinths) can be obtained from the cranial endocast. However, before the recent development of X-ray tomography as a palaeontological tool, these endocasts could not be studied non-destructively, and few detailed studies were undertaken. Here, we describe and illustrate the endocasts of six Palaeozoic lungfish from tomographic scans. We combine these with six previously described digital lungfish endocasts (4 fossil and 2 recent taxa) into a 12-taxon dataset for multivariate morphometric analysis using 17 variables. We find that the olfactory region is more highly plastic than the hindbrain, and undergoes significant elongation in several taxa. Further, while the semicircular canals covary as an integrated module, the utriculus and sacculus vary independently of each other. Functional interpretation suggests that olfaction has remained a dominant sense throughout lungfish evolution, and changes in the labyrinth may potentially reflect a change from nektonic to near-shore environmental niches. Phylogenetic implications show that endocranial form fails to support monophyly of the 'chirodipterids'. Those with elongated crania similarly fail to form a distinct clade, suggesting these two paraphyletic groups have converged towards either head elongation or truncation driven by non-phylogenetic constraints.

Liposomal Bupivacaine Suspension for Pain Control Following Ocular Evisceration Surgery.

PURPOSE: To determine the effectiveness of retrobulbar liposomal bupivacaine for controlling postoperative pain following evisceration, compared with 0.75% bupivacaine. METHODS: Randomized controlled trial, in which the postoperative pain scores from 24 patients who had retrobulbar liposomal bupivacaine after an evisceration were compared with the pain scores from 24 patients eviscerated using 0.75% bupivacaine. RESULTS: Patients who received liposomal bupivacaine reported significantly less pain at 24 hours (2.0 out of 10, p = 0.01) and 48 hours (2.2 out of 10, p = 0.01) after surgery than patients who received 0.75% bupivacaine (5.7, and 5.0, respectively). The postoperative pain scores at 1 hour and at 7 days did not significantly differ between the 2 groups. Significantly, fewer patients who received liposomal bupivacaine (0%) than patients who received 0.75% bupivacaine (16.7%) returned emergently during the postoperative period for uncontrolled pain (p ≤ 0.001). CONCLUSIONS: Retrobulbar liposomal bupivacaine is more effective than 0.75% bupivacaine for controlling pain during the first 2 days after evisceration and should be considered for patients undergoing this procedure.

A fairer way to compare researchers at any career stage and in any discipline using open-access citation data.

The pursuit of simple, yet fair, unbiased, and objective measures of researcher performance has occupied bibliometricians and the research community as a whole for decades. However, despite the diversity of available metrics, most are either complex to calculate or not readily applied in the most common assessment exercises (e.g., grant assessment, job applications). The ubiquity of metrics like the h-index (h papers with at least h citations) and its time-corrected variant, the m-quotient (h-index ÷ number of years publishing) therefore reflect the ease of use rather than their capacity to differentiate researchers fairly among disciplines, career stage, or gender. We address this problem here by defining an easily calculated index based on publicly available citation data (Google Scholar) that corrects for most biases and allows assessors to compare researchers at any stage of their career and from any discipline on the same scale. Our ε'-index violates fewer statistical assumptions relative to other metrics when comparing groups of researchers, and can be easily modified to remove inherent gender biases in citation data. We demonstrate the utility of the ε'-index using a sample of 480 researchers with Google Scholar profiles, stratified evenly into eight disciplines (archaeology, chemistry, ecology, evolution and development, geology, microbiology, ophthalmology, palaeontology), three career stages (early, mid-, late-career), and two genders. We advocate the use of the ε'-index whenever assessors must compare research performance among researchers of different backgrounds, but emphasize that no single index should be used exclusively to rank researcher capability.

Author Correction: Elpistostege and the origin of the vertebrate hand.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Elpistostege and the origin of the vertebrate hand.

The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian period (393-359 million years ago)1. These taxa-known as elpistostegalians-include Panderichthys2, Elpistostege3,4 and Tiktaalik1,5, none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian period of Canada, which represents-to our knowledge-the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates.

Neurocranial development of the coelacanth and the evolution of the sarcopterygian head.

The neurocranium of sarcopterygian fishes was originally divided into an anterior (ethmosphenoid) and posterior (otoccipital) portion by an intracranial joint, and underwent major changes in its overall geometry before fusing into a single unit in lungfishes and early tetrapods1. Although the pattern of these changes is well-documented, the developmental mechanisms that underpin variation in the form of the neurocranium and its associated soft tissues during the evolution of sarcopterygian fishes remain poorly understood. The coelacanth Latimeria is the only known living vertebrate that retains an intracranial joint2,3. Despite its importance for understanding neurocranial evolution, the development of the neurocranium of this ovoviviparous fish remains unknown. Here we investigate the ontogeny of the neurocranium and brain in Latimeria chalumnae using conventional and synchrotron X-ray micro-computed tomography as well as magnetic resonance imaging, performed on an extensive growth series for this species. We describe the neurocranium at the earliest developmental stage known for Latimeria, as well as the major changes that the neurocranium undergoes during ontogeny. Changes in the neurocranium are associated with an extreme reduction in the relative size of the brain along with an enlargement of the notochord. The development of the notochord appears to have a major effect on the surrounding cranial components, and might underpin the formation of the intracranial joint. Our results shed light on the interplay between the neurocranium and its adjacent soft tissues during development in Latimeria, and provide insights into the developmental mechanisms that are likely to have underpinned the evolution of neurocranial diversity in sarcopterygian fishes.

New information on Brindabellaspis stensioi Young, 1980, highlights morphological disparity in Early Devonian placoderms.

Acid-prepared specimens of the placoderm Brindabellaspis stensioi (Early Devonian of New South Wales, Australia) revealed placoderm endocranial anatomy in unprecedented detail. Brindabellaspis has become a key taxon in discussions of early gnathostome phylogeny, and the question of placoderm monophyly versus paraphyly. The anterior orientation of the facial nerve and related hyoid arch structures in this taxon resemble fossil osteostracans (jawless vertebrates) rather than other early gnathostomes. New specimens of Brindabellaspis now reveal the previously unknown anterior region of the skull, including an exceptionally elongate premedian bone forming a long rostrum, supported by a thin extension of the postethmo-occipital unit of the braincase. Lateral overlap surfaces indicate an unusual anterior position for the jaws. Digital rendering of a synchrotron radiation scan reveals a uniquely specialized ethmoid commissure sensory canal, doubled back and fused into a midline canal. The visceral surface of the premedian bone has a plexus of perichondral bone canals. An updated skull roof reconstruction of Brindabellaspis adds to the highly variable dermal skull patterns of the probably non-monophyletic 'acanthothoracids'. The unusual morphology revealed by the new specimens suggests that the earliest known reef fish fauna contained a diverse range of fishes with specialized ecological roles.

Safety Comparison of Laryngeal Mask Use With Endotracheal Intubation in Patients Undergoing Dacryocystorhinostomy Surgery.

PURPOSE: This study will determine the safety of laryngeal mask airway (LMA) compared with endotracheal tube (ETT) in patients undergoing general anesthesia for dacryocystorhinostomy (DCR) surgery. METHODS: In this retrospective cohort study, intraoperative and postoperative outcomes of patients who underwent DCR at UAB Callahan Eye Hospital using either LMA or ETT were compared. RESULTS: Over a period of 52 months, 429 patients underwent external DCR surgery. An ETT was used in 37 patients and LMA in 392 patients. Baseline patient characteristics and anesthetic management were similar. No documented cases of blood or gastric aspiration occurred in the total cohort. Our study confirmed the findings of others that there is less cardiovascular lability on LMA placement than with ETT intubation. A 30% increase in heart rate from baseline after intubation (ETT 10.8%, LMA 1.8%; p = 0.010) and after incision (ETT 8.1%, LMA 1.8%; p = 0.047) occurred more frequently in the ETT group. Airway management with an LMA was also less difficult compared with an ETT (ETT 5.7%, LMA 0.5%; p = 0.035). CONCLUSIONS: The use of an LMA for airway control is safe and effective in patients undergoing general anesthesia for DCR surgery. No events of aspiration occurred with LMA use. Heart rate increase was significantly less in the LMA group. In our opinion, use of an LMA for airway control during DCR surgery is superior to use of an ETT. Airway protection, improved hemodynamics, and less difficulty in placement of the laryngeal airway device are all validated by this study.

Neurocranial anatomy of an enigmatic Early Devonian fish sheds light on early osteichthyan evolution.

The skull of 'Ligulalepis' from the Early Devonian of Australia (AM-F101607) has significantly expanded our knowledge of early osteichthyan anatomy, but its phylogenetic position has remained uncertain. We herein describe a second skull of 'Ligulalepis' and present micro-CT data on both specimens to reveal novel anatomical features, including cranial endocasts. Several features previously considered to link 'Ligulalepis' with actinopterygians are now considered generalized osteichthyan characters or of uncertain polarity. The presence of a lateral cranial canal is shown to be variable in its development between specimens. Other notable new features include the presence of a pineal foramen, the some detail of skull roof sutures, the shape of the nasal capsules, a placoderm-like hypophysial vein, and a chondrichthyan-like labyrinth system. New phylogenetic analyses place 'Ligulalepis' as a stem osteichthyan, specifically as the sister taxon to 'psarolepids' plus crown osteichthyans. The precise position of 'psarolepids' differs between parsimony and Bayesian analyses.

Why Australasian vertebrate animals are so unique - A palaeontological perspective.

Australasia has a unique fauna of living vertebrates, which include the oldest known species on the planet (the lungfish Neoceratodus) as well as many diverse, highly endemic families of fish, amphibians, reptiles, birds and mammals. The origin of most of the Australian vertebrate fauna has developed from two phases. Firstly, when Australia was subsumed within the greater Gondwana landmass, migration of animals from one region to another was possible by a land connection. Many of our most primitive forms of reptiles and mammals probably entered the country at this time, such as varanids, madtsooid snakes, monotremes and basal marsupials. Secondly, following the breakup of Gondwana, the isolation of Australia for its last 40 million years and subsequent changing climatic conditions drove the radiation of marsupial, reptile and amphibian families within the continent. The gradual aridification of central Australia further divided the landmass into discrete regional areas characterised by rainfall, vegetation, and climatic zones.

Bayesian Morphological Clock Methods Resurrect Placoderm Monophyly and Reveal Rapid Early Evolution in Jawed Vertebrates.

The phylogeny of early gnathostomes provides an important framework for understanding one of the most significant evolutionary events, the origin and diversification of jawed vertebrates. A series of recent cladistic analyses have suggested that the placoderms, an extinct group of armoured fish, form a paraphyletic group basal to all other jawed vertebrates. We revised and expanded this morphological data set, most notably by sampling autapomorphies in a similar way to parsimony-informative traits, thus ensuring this data (unlike most existing morphological data sets) satisfied an important assumption of Bayesian tip-dated morphological clock approaches. We also found problems with characters supporting placoderm paraphyly, including character correlation and incorrect codings. Analysis of this data set reveals that paraphyly and monophyly of core placoderms (excluding maxillate forms) are essentially equally parsimonious. The two alternative topologies have different root positions for the jawed vertebrates but are otherwise similar. However, analysis using tip-dated clock methods reveals strong support for placoderm monophyly, due to this analysis favoring trees with more balanced rates of evolution. Furthermore, enforcing placoderm paraphyly results in higher levels and unusual patterns of rate heterogeneity among branches, similar to that generated from simulated trees reconstructed with incorrect root positions. These simulations also show that Bayesian tip-dated clock methods outperform parsimony when the outgroup is largely uninformative (e.g., due to inapplicable characters), as might be the case here. The analysis also reveals that gnathostomes underwent a rapid burst of evolution during the Silurian period which declined during the Early Devonian. This rapid evolution during a period with few articulated fossils might partly explain the difficulty in ascertaining the root position of jawed vertebrates.

The cranial endocast of Dipnorhynchus sussmilchi (Sarcopterygii: Dipnoi) and the interrelationships of stem-group lungfishes.

The first virtual cranial endocast of a lungfish from the Early Devonian, Dipnorhynchus sussmilchi, is described. Dipnorhynchus, only the fourth Devonian lungfish for which a near complete cranial endocast is known, is a key taxon for clarifying primitive character states within the group. A ventrally-expanded telencephalic cavity is present in the endocast of Dipnorhynchus demonstrating that this is the primitive state for "true" Dipnoi. Dipnorhynchus also possesses a utricular recess differentiated from the sacculolagenar pouch like that seen in stratigraphically younger lungfish (Dipterus, Chirodipterus, Rhinodipterus), but absent from the dipnomorph Youngolepis. We do not find separate pineal and para-pineal canals in contrast to a reconstruction from previous authors. We conduct the first phylogenetic analysis of Dipnoi based purely on endocast characters, which supports a basal placement of Dipnorhynchus within the dipnoan stem group, in agreement with recent analyses. Our analysis demonstrates the value of endocast characters for inferring phylogenetic relationships.

Early Gnathostome Phylogeny Revisited: Multiple Method Consensus.

A series of recent studies recovered consistent phylogenetic scenarios of jawed vertebrates, such as the paraphyly of placoderms with respect to crown gnathostomes, and antiarchs as the sister group of all other jawed vertebrates. However, some of the phylogenetic relationships within the group have remained controversial, such as the positions of Entelognathus, ptyctodontids, and the Guiyu-lineage that comprises Guiyu, Psarolepis and Achoania. The revision of the dataset in a recent study reveals a modified phylogenetic hypothesis, which shows that some of these phylogenetic conflicts were sourced from a few inadvertent miscodings. The interrelationships of early gnathostomes are addressed based on a combined new dataset with 103 taxa and 335 characters, which is the most comprehensive morphological dataset constructed to date. This dataset is investigated in a phylogenetic context using maximum parsimony (MP), Bayesian inference (BI) and maximum likelihood (ML) approaches in an attempt to explore the consensus and incongruence between the hypotheses of early gnathostome interrelationships recovered from different methods. Our findings consistently corroborate the paraphyly of placoderms, all 'acanthodians' as a paraphyletic stem group of chondrichthyans, Entelognathus as a stem gnathostome, and the Guiyu-lineage as stem sarcopterygians. The incongruence using different methods is less significant than the consensus, and mainly relates to the positions of the placoderm Wuttagoonaspis, the stem chondrichthyan Ramirosuarezia, and the stem osteichthyan Lophosteus-the taxa that are either poorly known or highly specialized in character complement. Given that the different performances of each phylogenetic approach, our study provides an empirical case that the multiple phylogenetic analyses of morphological data are mutually complementary rather than redundant.

A new method for reconstructing brain morphology: applying the brain-neurocranial spatial relationship in an extant lungfish to a fossil endocast.

Lungfish first appeared in the geological record over 410 million years ago and are the closest living group of fish to the tetrapods. Palaeoneurological investigations into the group show that unlike numerous other fishes-but more similar to those in tetrapods-lungfish appear to have had a close fit between the brain and the cranial cavity that housed it. As such, researchers can use the endocast of fossil taxa (an internal cast of the cranial cavity) both as a source of morphological data but also to aid in developing functional and phylogenetic implications about the group. Using fossil endocast data from a three-dimensional-preserved Late Devonian lungfish from the Gogo Formation, Rhinodipterus, and the brain-neurocranial relationship in the extant Australian lungfish, Neoceratodus, we herein present the first virtually reconstructed brain of a fossil lungfish. Computed tomographic data and a newly developed 'brain-warping' method are used in conjunction with our own distance map software tool to both analyse and present the data. The brain reconstruction is adequate, but we envisage that its accuracy and wider application in other taxonomic groups will grow with increasing availability of tomographic datasets.

Getting to the heart of a good fossil.

The discovery of perfectly preserved 113-119 million year old fossilised hearts in a Brazilian fish Rhacolepis has significant implications for palaeontology and comparative anatomy.

Interreader Variability of Computed Tomography for Orbital Floor Fracture.

IMPORTANCE: The timing and indications for repair of orbital floor fractures have been controversial. Current practice dictates that fractures involving more than 50% of the orbital floor should be repaired. Early management is initiated in such situations to prevent long-term sequelae of enophthalmos and diplopia. Because fracture size as measured by computed tomography (CT) is one of the criteria to determine the need for surgical repair, there is a need to know the reliability of this parameter. OBJECTIVE: To assess the variability of CT measurements of orbital floor fractures. DESIGN, SETTING, AND PARTICIPANTS: This study took place between January 1, 2005, and June 1, 2007, at an urban academic medical center. Patients with isolated orbital floor fractures were evaluated by 1 oculoplastic surgeon, and their orbital CT images were subsequently read by 3 neuroradiologists blinded to demographic information and the other readers' measurements. Separately, each was asked to determine the maximal anterior to posterior length and transverse width if a floor fracture existed. MAIN OUTCOMES AND MEASURES: Intraclass correlation coefficients were calculated for length and width using a 2-way mixed-effects model to evaluate the agreement between radiologists. RESULTS: Twenty-three patients met criteria for inclusion in this study (isolated orbital fracture thought to be in need of repair, with diplopia within 30° of primary gaze, and/or enophthalmos >2 mm, and/or 50% of the floor area involved in the fracture). The mean (SD) age of the patients was 31.5 (17.6) years (range, 8-73 years). The magnitude of agreement between the readers as measured by the intraclass correlation coefficient was 0.66 (95% CI, 0.46-0.82) for anterior to posterior length and 0.44 (95% CI, 0.22-0.69) for transverse width, indicating only a moderate degree of concordance. CONCLUSIONS AND RELEVANCE: Although the literature has long held that a floor fracture seen radiographically to involve 50% of the orbital floor has a high likelihood of enophthalmia and should be repaired, this study shows how variable CT measurements of orbital floor fractures can be in a clinical setting, even in trained hands. We question the dependence on such a criterion and reemphasize the importance of making surgical decisions based on clinical findings rather than radiological interpretations.