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.

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.

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.

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.

Copulation in antiarch placoderms and the origin of gnathostome internal fertilization.

Reproduction in jawed vertebrates (gnathostomes) involves either external or internal fertilization. It is commonly argued that internal fertilization can evolve from external, but not the reverse. Male copulatory claspers are present in certain placoderms, fossil jawed vertebrates retrieved as a paraphyletic segment of the gnathostome stem group in recent studies. This suggests that internal fertilization could be primitive for gnathostomes, but such a conclusion depends on demonstrating that copulation was not just a specialized feature of certain placoderm subgroups. The reproductive biology of antiarchs, consistently identified as the least crownward placoderms and thus of great interest in this context, has until now remained unknown. Here we show that certain antiarchs possessed dermal claspers in the males, while females bore paired dermal plates inferred to have facilitated copulation. These structures are not associated with pelvic fins. The clasper morphology resembles that of ptyctodonts, a more crownward placoderm group, suggesting that all placoderm claspers are homologous and that internal fertilization characterized all placoderms. This implies that external fertilization and spawning, which characterize most extant aquatic gnathostomes, must be derived from internal fertilization, even though this transformation has been thought implausible. Alternatively, the substantial morphological evidence for placoderm paraphyly must be rejected.

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.

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.

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.

Devonian arthrodire embryos and the origin of internal fertilization in vertebrates.

Evidence of reproductive biology is extremely rare in the fossil record. Recently the first known embryos were discovered within the Placodermi, an extinct class of armoured fish, indicating a viviparous mode of reproduction in a vertebrate group outside the crown-group Gnathostomata (Chondrichthyes and Osteichthyes). These embryos were found in ptyctodontids, a small group of placoderms phylogenetically basal to the largest group, the Arthrodira. Here we report the discovery of embryos in the Arthrodira inside specimens of Incisoscutum ritchiei from the Upper Devonian Gogo Formation of Western Australia (approximately 380 million years ago), providing the first evidence, to our knowledge, for reproduction using internal fertilization in this diverse group. We show that Incisoscutum and some phyllolepid arthrodires possessed pelvic girdles with long basipterygia that articulated distally with an additional cartilaginous element or series, as in chondrichthyans, indicating that the pelvic fin was used in copulation. As homology between similar pelvic girdle skeletal structures in ptyctodontids, arthrodires and chondrichthyans is difficult to reconcile in the light of current phylogenies of lower gnathostomes, we explain these similarities as being most likely due to convergence (homoplasy). These new finds confirm that reproduction by internal fertilization and viviparity was much more widespread in the earliest gnathostomes than had been previously appreciated.

The Prevalence of Air Regurgitation and Its Consequences After Conjunctivodacryocystorhinostomy and Dacryocystorhinostomy in Continuous Positive Airway Pressure Patients.

PURPOSE: To describe the prevalence of air regurgitation into the periocular region in continuous positive airway pressure (CPAP) patients with a history of conjunctivodacryocystorhinostomy with a Lester Jones tube and a dacryocystorhinostomy with silicone intubation, as well as problems caused by this regurgitation and methods to cope. METHODS: A retrospective chart review of patients who either underwent a conjunctivodacryocystorhinostomy or dacryocystorhinostomy was performed. Patients were contacted via phone interview. Demographic information, history of sleep apnea, use of CPAP, and presence of air regurgitation and associated complications were recorded. Institutional review board/ethics committee approval was obtained. RESULTS: Two patients who underwent a conjunctivodacryocystorhinostomy with Lester Jones tube and were on CPAP were identified. Both complained of air regurgitation, sensation of Lester Jones tube moving due to regurgitation, and periodic eye pain. Twenty-two patients who underwent a dacryocystorhinostomy with silicone stent and used CPAP were identified. Of these, 16 (72.7%) complained of air regurgitation. Difficulty sleeping (56.2%), dry eye symptoms upon waking (68.8%), eye pain upon waking (31.3%), and blurry vision upon waking (12.5%) were the commonest complaints due to air regurgitation. A total of 7 (43.7%) patients had to discontinue their CPAP at some point due to symptoms. CONCLUSIONS: This study brings to light the prevalence of air regurgitation in dacryocystorhinostomy procedures, and its associated symptoms. Given that this procedure is much more common than conjunctivodacryocystorhinostomy, surgeons should consider asking patients before performing surgery whether they use CPAP. Patients should be consented regarding the risk of air regurgitation and associated dry eye, foreign body sensation, and eye pain.

Live birth in the Devonian period.

The extinct placoderm fishes were the dominant group of vertebrates throughout the Middle Palaeozoic era, yet controversy about their relationships within the gnathostomes (jawed vertebrates) is partly due to different interpretations of their reproductive biology. Here we document the oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp. nov., from the Late Devonian Gogo Formation of Australia (approximately 380 million years ago). The new specimen, remarkably preserved in three dimensions, contains a single, intra-uterine embryo connected by a permineralized umbilical cord. An amorphous crystalline mass near the umbilical cord possibly represents the recrystallized yolk sac. Another ptyctodont from the Gogo Formation, Austroptyctodus gardineri, also shows three small embryos inside it in the same position. Ptyctodontids have already provided the oldest definite evidence for vertebrate copulation, and the new specimens confirm that some placoderms had a remarkably advanced reproductive biology, comparable to that of some modern sharks and rays. The new discovery points to internal fertilization and viviparity in vertebrates as originating earliest within placoderms.

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.

A Late Devonian coelacanth reconfigures actinistian phylogeny, disparity, and evolutionary dynamics.

The living coelacanth Latimeria (Sarcopterygii: Actinistia) is an iconic, so-called 'living fossil' within one of the most apparently morphologically conservative vertebrate groups. We describe a new, 3-D preserved coelacanth from the Late Devonian Gogo Formation in Western Australia. We assemble a comprehensive analysis of the group to assess the phylogeny, evolutionary rates, and morphological disparity of all coelacanths. We reveal a major shift in morphological disparity between Devonian and post-Devonian coelacanths. The newly described fossil fish fills a critical transitional stage in coelacanth disparity and evolution. Since the mid-Cretaceous, discrete character changes (representing major morphological innovations) have essentially ceased, while meristic and continuous characters have continued to evolve within coelacanths. Considering a range of putative environmental drivers, tectonic activity best explains variation in the rates of coelacanth evolution.

An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia.

How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

A novel surgical technique for the treatment of giant fornix syndrome.

PURPOSE: To describe a novel surgical treatment for patients with chronic relapsing conjunctivitis, corneal epitheliopathy, and ptosis secondary to giant fornix syndrome. METHODS: A retrospective case series was performed looking at the presence or absence of preoperative symptoms of eye irritation, tearing, blurry vision, and discharge in 6 patients diagnosed with giant fornix syndrome. Their examination findings were noted, and all patients underwent an extensive conjunctivoplasty with resection of redundant forniceal conjunctiva with subconjunctival antibiotics. Final visual acuity, symptoms, and examination findings were noted with a minimum follow up of 9 months. RESULTS: Six patients were treated from November 2009 to November 2011. Duration of symptoms ranged from 3 to 40 months. Four patients were women while 2 were men, with age ranging from 61 to 85 years. Common symptoms were severe mucopurulent discharge, eye redness, tearing, and irritation with examination findings of severe conjunctival discharge and injection, corneal epitheliopathy, upper eyelid ptosis, and a deep upper and lower eyelid fornix. Most patients had undergone previous treatments with topical and/or oral antibiotics or steroids. All patients underwent surgical intervention using the surgical technique to be described with resolution of their symptoms, and even an improvement of 2 or more lines of best corrected visual acuity (3 of 5 patients). CONCLUSIONS: The authors' novel surgical technique helps restore the abnormal anatomy found in patients with giant fornix syndrome and thus, helps resolve chronic relapsing conjunctivitis and surface disease associated with this often underdiagnosed condition. Further studies are needed to evaluate the risk of entropion and dry eye syndrome due to the modification of the posterior lamella.

An exceptional Devonian fish from Australia sheds light on tetrapod origins.

The transition from fishes to tetrapods was one of the most dramatic events in the evolution of vertebrates, but many pivotal fossils are incomplete, resulting in gaps in the data that are used for phylogenetic reconstruction. Here we present new observations from the most complete, acid-prepared Devonian tetrapodomorph fish yet discovered, Gogonasus, which was previously placed just crownward of Kenichthys and rhizodontids, the most primitive taxa on the tetrapod lineage. Unexpectedly, Gogonasus shows a mosaic of plesiomorphic and derived tetrapod-like features. Whereas the braincase and dermal cranial skeleton exhibit generalized morphologies with respect to Eusthenopteron or Panderichthys, taxa that are traditionally considered to be phyletically close to tetrapods, the presence of a deeply invaginated, wide spiracle, advanced internal spiracular architecture and near-horizontal hyomandibula are specialized features that are absent from Eusthenopteron. Furthermore, the pectoral fin skeleton of Gogonasus shares several features with that of Tiktaalik, the most tetrapod-like fish. A new phylogenetic analysis places Gogonasus crownward of Eusthenopteron as the sister taxon to the Elpistostegalia. Aspects of the basic tetrapod limb skeleton and middle ear architecture can now be traced further back within the tetrapodomorph radiation.

Diagnosis and management of an intraorbital vascular fistula.

A spontaneous intraorbital arteriovenous fistula is an extremely rare phenomenon. More commonly, arteriovenous fistulas occur spontaneously as carotid cavernous fistulas and dural cavernous fistulas or are secondary to trauma. Surgical approaches vary widely and each carries their own set of potential problems. The purpose of this single case report was to provide an example of a successful treatment of a rare, spontaneous intraorbital vascular fistula.

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.

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.

Patient experience with blepharoplasty.

PURPOSE: To prospectively study patients' postoperative experience with blepharoplasty and to determine how closely patients' expectations compare with their actual experience. METHODS: A prospective observational study of 51 consecutive patients undergoing bilateral upper eyelid blepharoplasty by a single surgeon (J.A.L.) between October 2008 and May 2009 was performed. Prior to surgery, patients were asked to rate, on a scale of 1 to 10, their expectations of pain, swelling, bruising, blurred vision, impairment of ability to function in daily activities, and itching. Patients were then asked to rate these 6 elements at 7 time points: 30 minutes, 4 hours, 24 hours, 2 days, 3 days, 1 week, and 2 months. The number of pain pills utilized was also assessed. An analysis of the data was performed to determine our patients' experience with blepharoplasty surgery. The paired t test was used to determine the statistical significance of patients' expectations compared with their actual reported experience. RESULTS: In this cohort of patients, the authors found the following: blurred vision and impairment in ability to function peaked in the immediate postoperative period, pain peaked at 4 hours, swelling and bruising peaked at 24 hours, and itching peaked at 3 days. The mean number of narcotic pain pills used by patients in the postoperative period was 2.45. Patients underestimated the degree of swelling, blurred vision, and impairment in ability to function experienced following surgery. CONCLUSIONS: Postoperative patient experience with blepharoplasty is based largely on anecdotal evidence; the data from this study will facilitate more objectively based preoperative counseling.