Distal Tarsus Research Articles

Hindlimb Skeletal Structure of the Green-winged Macaw: An Anatomical Study

In birds, the forelimb bones undergo modification to facilitate muscle attachment for flight, enabling the movement of wings up and down. Conversely, hindlimb bones primarily support walking and perching functions, necessitating evolutionary adaptations in their structure. Therefore, this study aims to document the gross anatomical features of hind limb bones in Green-winged Macaws, including the femur, tibio-tarsus, tarsometatarsus, and digits. The bones were sourced from six Green-winged Macaw carcasses undergoing post-mortem examination at the Department of Veterinary Pathology, Madras Veterinary College, Chennai. Preparation was conducted using the wet maceration technique. In the femur, the proximal end displayed a large, well-defined spherical head medially, accompanied by a small depression called the fovea capitis, and a distinct neck. The tibio-tarsus exhibited a small roughened area on its lateral border for fibula attachment, with a larger medial and smaller lateral condyle at the proximal extremity, along with a linear cinemal crest along the medial border. The fibula's distal extremity tapered into a free point, articulating at the caudolateral aspect of the tarsometatarsus. The tarsometatarsus displayed fused distal tarsals with metatarsals II, III, and IV, while Metatarsus I remained a separate bone, forming the base of the first toe. The proximal extremity of the tarsometatarsus featured two large concave articular facets for condyles from the distal extremity of the tibio-tarsus, and a facet for the distal end of the fibula caudolaterally. The Macaw's hind limb consisted of four digits, forming a zygodactyl foot arrangement.

Morphology and ontogeny of carpus and tarsus in stereospondylomorph temnospondyls.

Skeletal development is well known in temnospondyls, the most diverse group of Paleozoic and Mesozoic amphibians. However, the elements of carpus and tarsus (i.e., the mesopodium) were always the last bones to ossify relative to the other limb bones and with regard to the rest of the skeleton, and are preserved only in rare cases. Thus, in contrast to the other parts of the limb skeleton, little is known about the ontogeny and sequence of ossification of the temnospondyl carpus and tarsus. We intended to close this gap by studying the ontogenies of a number of Permo/Carboniferous stereospondylomorphs, the only temnospondyls with preserved growth series in which the successive ossification of carpals and tarsals can be traced. Studying the degree of mesopodial ossification within the same species show that it is not necessarily correlated with body size. This indicates that individual age rather than size determined the degree of mesopodial ossification in stereospondylomorphs and that the largest individuals are not necessarily the oldest ones. In the stereospondylomorph tarsus, the distal tarsals show preaxial development in accordance with most early tetrapods and salamanders. However, the more proximal mesopodials exhibit postaxial dominance, i.e., the preaxial column (tibiale, centrale 1) consistently started to ossify after the central column (centralia 2-4, intermedium) and the postaxial column (fibulare). Likewise, we observed preaxial development of the distal carpals in the stereospondylomorph carpus, as in most early tetrapods for which a statement can be made. However, in contrast to the tarsus, the more proximal carpals were formed by preaxial development, i.e., the preaxial column (radiale, centrale 1) ossified after the central column (centralia 2-4, intermedium) and before the postaxial column (ulnare). This pattern is unique among known early tetrapods and occurs only in certain extant salamanders. Furthermore, ossification proceeded from distal to proximal in the central column of the stereospondylomorph carpus, whereas the ossification advanced from proximal to distal in the central column of the tarsus. Despite these differences, a general ossification pattern that started from proximolateral (intermedium or centrale 4) to mediodistal (distal tarsal and carpal 1) roughly in a diagonal line is common to all stereospondylomorph mesopodials investigated. This pattern might basically reflect the alignment of stress within the mesopodium during locomotion. Our observations might point to a greater variability in the development of the mesopodium in stereospondylomorphs and probably other early tetrapods than in most extant tetrapods, possibly mirroring a similar variation as seen in the early phases of skeletogenesis in salamander carpus and tarsus.

Impact of periarticular osteophytes of the distal tarsus diagnosed in nonlame yearling Standardbred horses on racing performance.

The aim of this study was to identify the radiographic prevalence of periarticular osteophytes of the distal tarsus in nonlame yearling Standardbred horses, and to evaluate its potential impact on race performance. Cross-sectional cohort study. Client-owned yearling Standardbred horses (n = 416). Bilateral tarsal radiographs were available from all horses for review. Osteophytes were measured on radiographs using clinical visualization software and categorized by size. Racing records were obtained from the United States Trotting Association. Regression analysis was used to determine associations between presence or size of periarticular osteophytes and performance parameters with sex and gait covariates. Of 416 Standardbred yearlings without clinical lameness, 113 (27.1%) had distal tarsal periarticular osteophytes. Regression analyses revealed few associations between the presence of periarticular osteophytes and performance parameters. Affected horses had fewer starts at 4 years of age (incident rate ratio [IRR] 0.92, p = .01) and fewer lifetime starts (IRR 0.95, p = .003), but the effect size was small. Within the affected group, osteophyte size was only associated with number of starts at 3 (IRR 0.67, p < .0001). Sex and gait affected many performance parameters. The prevalence of distal tarsal periarticular osteophytes was similar to that in other breeds. Periarticular osteophytes of the distal tarsus appeared to be a largely incidental finding in nonlame yearling Standardbreds intended for harness racing. Distal tarsal periarticular osteophytes in young, nonlame Standardbred horses should affect racing potential only minimally. This is in contrast to reports from other disciplines.

New information on gorgonopsian pedal morphology based on articulated material from Zambia.

Descriptions detailing the postcranial skeleton of gorgonopsians lag far behind those of the group's cranial anatomy. Indeed, most recent phylogenetic recent work has focused exclusively on cranial features, leaving systematic variation in the rest of the skeleton undocumented. Here I describe the articulated pedes of a small gorgonopsian from the upper Permian upper Madumabisa Mudstone Formation of Zambia's Luangwa Basin. Between the two sides, the pedal phalangeal formula can be confidently reconstructed as 2-3-4-5-4, with one disc-like phalanx present in digits three and five, and two discs present in digit four. The lateralmost distal tarsal is confirmed to be a compound element formed by the fusion of distal tarsals four and five, as evidenced by a groove circumscribing the distolateral corner of the element. Nonetheless, a prominent gap was probably present proximal to metatarsal five. A preliminary review of variation in the relative sizes and orientations of the pedal elements shows the possibility that this anatomical unit could contribute phylogenetically useful data. For example, the presence of a disc-like phalanx in digit five likely represents the retention of the primitive phalangeal formula of the pes compared to its absence in a specimen tentatively referred to the derived rubidgeine gorgonopsian Dinogorgon, but this hypothesis requires testing within a broader phylogenetic context.

Ankle structure of the Tokay gecko (Gekko gecko) and its role in the deployment of the subdigital adhesive system.

The remarkable ability of geckos to adhere to smooth surfaces is often thought of in terms of external structures, including the branching setae that make contact with the surface producing van der Waals forces. Some geckos also exhibit unique movements of the distal segments of the limbs during locomotion and static clinging, including active digital hyperextension and considerable pedal rotation. During static clinging, geckos can exhibit considerable adduction/abduction of the pes while the crus and thigh remain firmly adpressed to the substratum. This decoupling of pedal adduction/abduction from ankle flexion/extension and pedal long-axis rotation is a significant departure from pedal displacements of a typical lizard lacking adhesive ability. The structure of the ankle is likely key to this decoupling, although no detailed comparison of this complex joint between pad-bearing geckos and other lizards is available. Here we compare the configuration of the mesotarsal joint of nongekkotan lizards (Iguana and Pristidactylus) with that of the Tokay gecko (Gekko gecko) using prepared skeletons, scanning electron microscopy, and micro-computed tomographic (µCT) scans. We focus on the structure of the astragalocalcaneum and the fourth distal tarsal. The mesotarsal joint exhibits a suite of modifications that are likely associated with the secondarily symmetrical pes of pad-bearing geckos. For example, the lateral process of the astragalocalcaneum is much more extensive in G. gecko compared with other lizards. The mesotarsal joint exhibits several other differences permitting dissociation of long-axis rotation of the pes from flexion-extension movement, including a reduced ventral peg on the fourth distal tarsal, an articulatory pattern dominated by a well-defined, expansive distomesial notch of the astragalocalcaneum, and an associated broad proximodorsal articulatory facet of the fourth distal tarsal. Pad-bearing geckos are capable of effectively deploying their intricate adhesive system across a broad array of body angles because of this highly modified ankle. Future research should determine whether the differences encountered in G. gecko (and their extent) apply to the Gekkota as a whole and should examine how the elements of the ankle move dynamically during locomotion across a range of taxa.

Radiological, vascular osteochondrosis occurs in the distal tarsus, and may cause osteoarthritis.

Osteochondrosis occurs due to failure of the blood supply to growth cartilage. Osteochondrosis lesions have been identified in small tarsal bones and suggested to cause distal tarsal osteoarthritis; however, it has not been determined whether distal tarsal osteochondrosis lesions were the result of vascular failure. To perform post-mortem arterial perfusion and micro-computed tomography (CT) of the central (CTB) and third tarsal bones (TIII) of fetuses and foals up to 5months old, to describe tarsal development and any lesions detected. Descriptive, nonconsecutive case series. Twenty-three animals that died or were euthanased from 228days of gestation to 5months old were collected, comprising two fetuses and nine foals of miscellaneous breeds and 12 Icelandic Horse foals, a breed with high prevalence of distal tarsal osteoarthritis. One hindlimb from each foal was perfused arterially with barium, and the CTB and TIII were examined with micro-CT. Perfusion yielded partial information from 41% of the animals. The CTB and TIII were supplied by nutrient arteries and perichondrial vessels with vertical, transverse and circumferential configurations. Fourteen of the 23 (61%) animals had focal defects in the ossification front, that is, radiological osteochondrosis. The majority of lesions matched the configuration and development of vertical vessels. Additionally, full-thickness, cylindrical defects matched transverse vessels, and the long axes of some dorsal lesions matched circumferential vessels. Lack of histological validation. Post-mortem perfusion was poor for examination of the blood supply to the growth cartilage of the CTB and TIII. Radiological osteochondrosis lesions were compatible with vascular failure because they were focal, and because lesion geometry matched vessel configuration. The relationship between osteochondrosis and distal tarsal osteoarthritis warrants further investigation.

Multidisciplinary Approach for the Management and Treatment of Diabetic Foot Infections with a Resorbable, Gentamicin-Loaded Bone Graft Substitute.

Diabetic patients are at increased risk of developing foot ulcers which may cause bone infections associated with a high probability of both amputation and mortality. Therefore, prompt diagnosis and adequate treatment are of key importance. In our Diabetic Foot Unit, effective multidisciplinary treatment of osteomyelitis secondary to diabetes involves the application of a gentamicin-eluting calcium sulphate/hydroxyapatite bone graft substitute to fill residual bone voids after debridement. The data of all patients treated with the gentamicin-eluting calcium sulphate/hydroxyapatite bone graft substitute for diabetic foot infections with ulcer formation and osteomyelitis at metatarsals, calcaneus and hindfoot at our institute from July 2013 to September 2016 were retrospectively collected and evaluated. A total of 35 patients were included in this retrospective single-arm case series and were either continuously followed up for at least one year or until healing was confirmed. Nineteen lesions affected the distal row of tarsus/talus, ten the calcaneus and a further six were located at the metatarsals. While all of the metatarsal lesions had healed at 1-year follow-up, the healing rate in the hindfoot region was lower with 62.5% at the calcaneus and 72.2% at the distal tarsus and talus at 12 months, respectively. The overall cure rate for ulcerous bone infection was 81.3%. In two calcaneal lesions (25%) and two lesions of distal tarsus/talus (11.1%) amputation was considered clinically necessary. Promising results were achieved in the treatment of diabetic foot infections with soft tissue ulcers by a multidisciplinary approach involving extensive debridement followed by adequate dead space management with a resorbable gentamicin-eluting bone graft substitute.

Reassessment of the Triassic archosauriform Scleromochlus taylori: neither runner nor biped, but hopper.

The six known specimens of Scleromochlus taylori and casts made from their negative impressions were examined to reassess the osteological evidence that has been used to interpret Scleromochlus’s locomotion and phylogenetic relationships. It was found that the trunk was dorsoventrally compressed. The upper temporal fenestra was on the lateral surface of skull and two-thirds the size of the lower, the jaw joint posteriorly placed with short retroarticular process, and teeth short and subconical, but no evidence of external nares or antorbital fossae was found. The posterior trunk was covered with ~20 rows of closely spaced transversely elongate dorsal osteoderms. The coracoid was robust and elongate. The acetabulum was imperforate and the femoral head hemispherical and only weakly inturned such that the hip joint was unsuited to swinging in a parasagittal plane. The presence of four distal tarsals is confirmed. The marked disparity of tibial and fibular shaft diameters and of proximal tarsal dimensions indicates that the larger proximal tarsal is the astragalus and the significantly smaller tarsal is the calcaneum. The astragalus and calcaneum bear little resemblance to those of Lagosuchus, and the prominent calcaneal tuber confirms that the ankle was crurotarsal. There is no evidence that preserved body and limb postures are unnatural, and most specimens are preserved in what is interpreted as a typical sprawling resting pose. A principal component analysis of skeletal measurements of Scleromochlus and other vertebrates of known locomotor type found Scleromochlus to plot with frogs, and that finding combined with skeletal morphology suggests Scleromochlus was a sprawling quadrupedal hopper. Phylogenetic analyses found that Scleromochlus was not an ornithodiran, but was either within the Doswelliidae or outside the clade consisting of the most recent common ancestor of the Erythrosuchidae and Archosauria and all its descendants.

Foals Developmental Orthopedic Disease Associated with Metabolic and Biometric Characterization of Pregnant Overweight Crioulo Mares

Background: Musculoskeletal changes in growing foals can be linked to metabolic disorders which affect the cartilage metabolism associated of obesity during the late gestation of the mares, negatively affecting the athletic performance of the otherwise prospective foals. High basal insulin levels can be associated with increased weight and obesity of the mares, altering the supply of the glucose to the fetus and the production of IGF-1, which plays an important role in the endochondral cartilage metabolism. The present study aims to describe the association of the articular and the physeal possible lesions and the IGF-1 levels of the foals to metabolic and biometric measurements alterations of the overweight Crioulo mares in the late gestation.Materials, Methods &amp; Results: A prospective and observational cohort study was conducted using the foals and the overweight mares at field conditions. Twenty-eight foals and their overweight mothers were utilized. The foals’ biometric and metabolic features as weight and height; glucose, total cholesterol, cholesterol HDL, triglycerides, basal insulin, leptin, glucose, total T4 and IGF-1 were analyzed, from the birth until the weaning period around sixth month of life of it. All the foals, at the weaning period, were submitted to the radiograph examination of the tarsal joints and the metacarpal-phalangeal joints to evaluate signs of lesions and the possible distal metacarpal physeal changes, respectively. The mares’ biometric and metabolic features as weight, height and fat tail-head deposition; basal insulin, leptin, glucose, total cholesterol, cholesterol HDL and triglycerides were analyzed at the final period of gestation. The basal insulin levels of the foals at the second, fourth and sixth month of life were 9.87 + 1.82 µUI/mL, 9.13 + 1.94 µUI/mL, 9.39 + 2.54 µUI/mL. The IGF-1 levels of the foals at the second, third, fourth, fifth and sixth month of life were 290.27 + 79.72 ng/mL; 180.77 + 66.22 ng/mL; 151.79 + 46.64 ng/mL; 110.81 + 33.13 ng/mL and 89.59 + 14.00 ng/mL. Foals presented osteoarthritis (92.85%) of the distal tarsal joints and 50% of it presented physitis of the distal metacarpal epiphyseal plate. The weight and the basal insulin levels of the mares at the last three months of gestation were 501.80 + 6.4 kg, 511.76 + 8.0 kg, 533.23 + 8.2 kg and 11.7 + 2.1 µUI/mL, 9.8 + 1.1 µUI/mL, 13.7 + 1.6 µUI/mL, respectively.Discussion: In the present study, from the second to the sixth month of the period life, the foals showed IGF-1 levels of 290 to 89 ng/mL, and demonstrated, at 6-month-old, a prevalence of 92.85% of distal tarsus lesions and 50% of physitis of the distal metacarpal epiphyseal plate. In association, the overweight mares showed an increase of the insulin basal levels when nearing parturition. The occurrence of physitis in 50% of the 6-month-old foals in the present study demonstrate that the metabolic changes are involved in this process and the IGF-1 levels were observed to be lower than in healthy foals of other breeds. The lower IGF-1 levels during the developmental period of the foals are associated with a decrease of bone density and mass, musculoskeletal atrophy and osteoarthritis. In the present study, the decreasing curve of IGF-1 levels (P &lt; 0.05) of the foals, from the second to sixth month of life, is similar to others researches with foals from other breeds from 0 to 7 months of life. In previous researches with Crioulo horses, it was observed that foals aged less than 18 months had up to 100% of prevalence of articular tarsus lesions. This suggest that the tarsus lesions observed in 92.85% of the 6-month-old foals in the present study, could not heal and that lesions should remain in the foals to adulthood.

Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: postcranial skeleton

PRISM FUND TRINITY COLLEGE CAMBRIDGE ST JOHN'S COLLEGE OXFORD SMITHSONIAN INSTITUTION (WASHINGTON DC)

Lethal mutations in Euphydryas aurinea beckeri (Lederer, 1853) (Lepidoptera: Nymphalidae) from Sierra Blanca, Malaga, Spain

Two Euphydryas aurinea beckeri females from Sierra Blanca, Malaga, Spain were captured and returned to the U.K.; each laid a single egg batch on Succisa pratensis. Both batches hatched and the resulting larvae were reared through to adulthood. One group of larvae produced butterflies with three different mutations: pupae with spines, legs lacking distal tarsals and claws, and with appendages attached to the genitalia which protruded though the rear of the abdomens in both males and females. The other group of larvae produced normal males and females.

A new stem hynobiid salamander (Urodela, Cryptobranchoidea) from the Upper Jurassic (Oxfordian) of Liaoning Province, China

ABSTRACTHynobiids are a group of small- to moderate-sized salamanders living primarily in Asia. They are a primitive crown-group clade, with a poor fossil record. Several hynobiid-like taxa have been discovered from the Lower Cretaceous strata of northern China during the last 20 years, with Liaoxitriton zhongjiani and Nuominerpeton aquilonaris identified as the oldest known stem hynobiids. However, the record of pre-Cretaceous hynobiid-like taxa is only known by Liaoxitriton daohugouensis, of which both the morphology and the congeneric status with L. zhongjiani remain problematic. Here, we report on a new hynobiid-like salamander, Linglongtriton daxishanensis, gen. et sp. nov., on the basis of two specimens from the Upper Jurassic Lanqi/Tiaojishan Formation (∼160 Ma) of Liaoning Province, China. Linglongtriton is diagnosed by a unique combination of features revealed by both observation under microscope and micro-computed tomography (μCT) scan of the holotype, including nasals separated from each other at the midline; prootic, opisthotic, and exoccipital retained as discrete elements; dentary with a lateral groove; articular not ossified; metacarpal III enlarged; a single centrale; and distal tarsals 4 and 5 fused into a single element. Phylogenetic analysis identified Linglongtriton and several other hynobiid-like taxa, including Liaoxitriton daohugouensis, as stem hynobiids, thereby extending the temporal range of the stem by at least 40 Ma—from the Early Cretaceous (Aptian–Barremian) to the Middle Jurassic (Bathonian). Comparative study of Linglongtriton with living and fossil hynobiids sheds new lights on the evolution and developmental mechanisms of several characters, including nasal separation and tarsal elements.

The relationship between sagittal hoof conformation and hindlimb lameness in the horse.

Lameness can be multifactorial and may result from the accumulation of multiple seemingly unrelated causes. The identification of factors associated with lameness could be one method to decrease incidence of lameness and prolong the equine athlete's competitive life. To determine if there is an association between hoof balance in the sagittal plane and hindlimb lameness. Case-control study. Eighty client-owned horses with hindlimb lameness (cases) and 80 horses with no detectable hindlimb lameness (controls) were prospectively enroled following lameness evaluation as either cases (lameness localised with regional anaesthesia) or controls (no hindlimb lameness). Lameness cases were divided based on location (stifle, tarsus, proximal metatarsus and other sites). Lateromedial radiographs were performed on hind hooves and plantar angle of the distal phalanx (PADP) was determined. The prevalence of negative/neutral PADP and median PADPs were calculated. Conditional logistic regression and Wilcoxon signed rank tests were used to analyse PADPs, and odds ratios were calculated. Significance was set at P<0.05. The mean PADP was significantly smaller in cases compared to controls. The mean PADP was significantly smaller in horses with lameness localised to tarsus and proximal suspensory, but not the stifle. Lameness in horses was associated with a negative/neutral PADP (Odds ratio [OR] 3.87, 95% confidence interval [95% CI] 1.97-7.61, P<0.01), with lameness localised to the tarsus (OR 4.98, 95% CI 1.34-18.54, P=0.01) and proximal suspensory (OR 5.16, 95% CI 1.11-23.89, P=0.03) being associated with a negative/neutral PADP. It is unknown whether the negative/neutral PADP contributed to lameness or lameness resulted in lower PADP. Horses with hindlimb lameness localised to the distal tarsus and proximal metatarsus, but not the stifle, were more likely to have negative/neutral PADPs. Corrective farriery to improve PADP may be investigated further as one component in the treatment of hindlimb lameness localised to regions proximal to the foot. The Summary is available in Portuguese - see Supporting Information.

High field magnetic resonance imaging contributes to diagnosis of equine distal tarsus and proximal metatarsus lesions: 103 horses.

Injury of the distal tarsus and proximal metatarsus commonly causes lameness. Magnetic resonance imaging (MRI) allows concurrent assessment of both the distal tarsal joints and suspensory ligament origin, and aids identification of lesions that may otherwise go undetected by other modalities. In this retrospective observational study, the medical records of a veterinary imaging center were searched for MRI exams of the distal tarsus and proximal metatarsus for the years 2012 through 2014. Studies for 125 limbs of 103 horses were identified and retrospectively evaluated by two board-certified veterinary radiologists. Soft tissue and osseous changes were characterized and graded by degree of severity. The patients' signalment, lameness severity, and results of diagnostic analgesia were recorded. Osteoarthritic changes of the distal intertarsal and tarsometatarsal joints were the most common findings. Other findings included bone marrow lesions, degenerative changes of the small cuboidal bones, subchondral cystic lesions, and intertarsal desmopathy. Suspensory ligament desmopathy was found in 53% of limbs. Fourty-seven percent of limbs that responded to analgesia of the proximal suspensory ligament had more severe lesions in the distal tarsus. Bone marrow lesions of the third tarsal bone were the only MRI finding that correlated with grade of lameness in patients for which lameness grade was reported. The grade of lameness has a poor correlation with the severity of lesions found on MRI. The findings support the use of MRI for simultaneous evaluation of the proximal metatarsus and distal tarsus, particularly given the difficulty of lesion localization with diagnostic analgesia.

Fact or fiction: what can diagnostic anaesthesia really tell us?

Diagnostic anaesthesia is a key part of lameness investigation but aberrant results are often seen, which can be confusing. An appreciation of both the strengths and limitations of diagnostic analgesia is essential. Anatomically complex regions, such at the distal limb, distal carpus and distal tarsus, can be particularly challenging. Clinical experience and good anatomical knowledge are beneficial, as is an appreciation of relevant research. This article explores the subjectivity of diagnostic analgesia on a block-by-block basis, including a review of the peer reviewed literature, with a view to managing owner expectations.

Structure and evolution of the ankle bones in pterosaurs and other ornithodirans

ABSTRACTThe ankle bone assembly of pterosaurs has received little attention, even though it is critical for understanding the functional morphology of the leg and the foot and has far-reaching implications for interpretations of stance and gait in ornithodirans in general, as well as for any role the leg may have had in the flight of pterosaurs. Of particular importance are the distal tarsal bones, which are seldom preserved clearly. Their concave proximal facets articulate with the medial and lateral condyles (comprising the astragalus and, at least basally, the calcaneum) of the tibiotarsus. Distally, they articulate with metatarsals II–IV, and the relatively large metatarsal V articulates on the distolateral side of the lateral distal tarsal. The homology of these bones in pterosaurs can be established with reference to other early-branching ornithodirans, and the morphology of the bones implies similar functional roles and ranges of motion. The medial distal tarsal is likely the fusion of distal tarsals 2 + 3, and the lateral distal tarsal is distal tarsal 4, a pattern reflected in ontogeny. The pterosaur ankle was capable of plantarflexion, but adduction and abduction of the feet were greatly limited. A synoptic survey of available tarsal bones of pterosaurs shows that the morphology of these bones remained relatively unchanged from the most basal pterosaurs to the pteranodontids and the azhdarchoids. Comparisons among a variety of ornithodirans show that the basic functional pattern did not vary importantly, although some ornithodiran subgroups evolved unique schemes of development and sequential ossification.Citation for this article: K. Padian. 2017. Structure and evolution of the ankle bones in pterosaurs and other ornithodirans. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1364651.

Upper lid crease approach for margin rotation in trachomatous cicatricial entropion without external sutures.

To describe the use of a lid crease incision for upper eyelid margin rotation in cicatricial entropion combining internal traction on the anterior lamella, tarsotomy, and tarsal overlap without external sutures. Surgical description: The main steps of the procedure consisted of exposure of the entire tarsal plate up to the eyelashes followed by tarsotomy through the conjunctiva. A double-armed 6.0 polyglactin suture was then passed through the distal tarsal fragment to the marginal section of the orbicularis oculi muscle. As the sutures were tied, the distal tarsus advanced over the marginal section, and traction was exerted on the marginal strip of the orbicularis muscle. There were no bolsters or external knots. The pretarsal skin-muscle flap was closed with a 6.0 plain gut suture. We used this procedure at a tertiary hospital in Saudi Arabia from 2013 to 2014. Sixty upper lids of 40 patients (23 women and 17 men) were operated on, with an age range of 44-99 years [mean ± standard deviation (SD) = 70.9 ± 13.01 years]. Bilateral surgery was performed on 21 patients. Follow-up ranged from 1 to 12 months (mean 3.0 ± 2.71 months). Forty percent of the patients (24 lids) had more than 3 months' follow-up. The postoperative lid margin position was good in all cases. Trichiasis (two lashes) was observed in only one patient with unilateral entropion on the medial aspect of the operated lid. The upper lid margin can be effectively rotated through a lid crease incision with internal sutures. The technique combines the main mechanisms of the Wies and Trabut approaches and avoids the use of bolsters or external sutures, which require a second consultation to be removed. Some other lid problems, such as ptosis, retraction, or dermatochalasis, can be concomitantly addressed during the procedure.

Reverse saphenous conduit flap in small animals: Clinical applications and outcomes.

Due to the lack of skin elasticity defects of the distal hind limb can be a challenge to close. This article assesses a well-described, but completely under-used technique for closure of wounds on the distal tarsus. The technique was used with good success in six cases presenting to the Bryanston Veterinary Hospital with a wide range of underlying pathology ranging from trauma to neoplastic disease of the tarsus. All six cases were treated with a reverse saphenous conduit flap and two of them underwent radiation therapy with no adverse side effects. All cases showed excellent results with a very low degree of flap necrosis that never exceeded 15% of the total flap area. This skin flap provides an excellent treatment method that is reliable in closure of defects of the distal tarsus with few adverse effects. To the author's knowledge there has been only one previously published report on the clinical use of this type of skin flap, even though the flap is well described in most texts.

The hooked element in the pes of turtles (Testudines): a global approach to exploring primary and secondary homology.

The hooked element in the pes of turtles was historically identified by most palaeontologists and embryologists as a modified fifth metatarsal, and often used as evidence to unite turtles with other reptiles with a hooked element. Some recent embryological studies, however, revealed that this element might represent an enlarged fifth distal tarsal. We herein provide extensive new myological and developmental observations on the hooked element of turtles, and re-evaluate its primary and secondary homology using all available lines of evidence. Digital count and timing of development are uninformative. However, extensive myological, embryological and topological data are consistent with the hypothesis that the hooked element of turtles represents a fusion of the fifth distal tarsal with the fifth metatarsal, but that the fifth distal tarsal dominates the hooked element in pleurodiran turtles, whereas the fifth metatarsal dominates the hooked element of cryptodiran turtles. The term 'ansulate bone' is proposed to refer to hooked elements that result from the fusion of these two bones. The available phylogenetic and fossil data are currently insufficient to clarify the secondary homology of hooked elements within Reptilia.

Radial arrangement of Janus-like setae permits friction control in spiders

Dynamic attachment is the key to move on steep surfaces, with mechanisms being still not well understood. The hunting spider Cupiennius salei (Arachnida, Ctenidae) possesses hairy attachment pads (claw tufts) at its distal legs, consisting of directional branched setae. The morphological investigation revealed that adhesive setae are arranged in a radial manner within the distal tarsus. Friction of claw tufts on smooth glass was measured to reveal the functional effect of seta arrangement within the pad. Measurements revealed frictional anisotropy in both longitudinal and transversal directions. Contact behaviour of adhesive setae was investigated in a reflection interference contrast microscope (RICM). Observations on living spiders showed, that only a small part of the hairy pads is in contact at the same time. Thus the direction of frictional forces is depending on leg placement and rotation. This may aid controlling the attachment to the substrate.