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Embolomeres have been considered candidate stem-amniotes by many authors, but recent work has shown that anatomical and phylogenetic support for this hypothesis may be ambiguous. Newer phylogenetic approaches focus on the anatomy of the endochondral bones surrounding the brain (neurocranium) and associated dermal investing bones, so accurate description of the neurocranium of tetrapods, and particularly embolomeres, is critical to assess the phylogenetic context of amniote origins. I here amend prior descriptions of the neurocranium of the abundant Early Permian embolomere, Archeria crassidisca , with a description of a previously unreported partial braincase. This specimen reveals features broadly associated with stem-tetrapods of the fin-to-limb transition and recently described in aïstopod stem-tetrapods, including a cranial notochordal remnant, a possible buccohypophyseal canal, and anteroventrally projecting saccular fossae that extend deep into the basioccipital. I present an amended description and reconstruction of the neurocranium and a phylogenetic analysis integrating these codings, which recovers embolomeres more robustly within the tetrapod stem. I review characters previously used to assign embolomeres to the amniote stem and find this evidence is ambiguous or incorrect. I then outline strong character support for a stem-tetrapod position of embolomeres, and implications for the ancestral body plan of crown-group tetrapods. [ABSTRACT FROM AUTHOR]

Introduction: Crested chickens show abnormalities in their anatomy of the skull, endocranium, and brain (including cerebral elongation) and can be appropriate model systems for neuroanatomical evolution, brain-skull integration, and skull and brain deformities. Here, we give a detailed comprehensive description of the skull of crested chickens using the example of the Padovana chicken, including ontogenetic aspects and an allometric analysis of their brain size. Methods: In total, 109 chickens of two different strains of the Padovana chicken were hatched together. All animals were X-rayed weekly during growth. Nine juvenile (ready for hatch) and 22 adult skulls were processed for histology and morphological descriptions, and a further 20 individuals were processed for brain analysis. Results: At hatching, all chicks were already crested, and a distinctive bony protuberance was first observed at the age of 4 weeks. Juvenile chickens exhibit either an open neurocranium or a protuberance. In the adult skull, foramina of different sizes can be found in the frontal bone, but no completely open neurocrania are observed in juveniles. Particularly in Padovana with cranial protuberances, several peculiarities can be observed in the os mesethmoidale, os nasale, os praemaxillare, orbit, and cranial fossae. Additionally, the brain of Padovana with cranial protuberances looks drawn in length with the shape of an hourglass and showed significantly larger encephalization indices than plain-headed breeds, topped only by another crested chicken breed. Discussion: Investigations on chickens with cerebral elongation may facilitate the understanding of skull and brain dysplasia and may provide meaningful insights into cerebral hernia development. Additionally, crested breeds, combined with standard chickens, form a promising comparative system for investigating the emergence of novel brain and skull morphologies. [ABSTRACT FROM AUTHOR]

We conducted a phylogenetic analysis of genetic and anatomical data focusing on golden moles (Chrysochloridae) and tenrecs (Tenrecidae). Our results support the now well-resolved topology for extant tenrecids, in addition to the paraphyly of 'Chrysochlorinae' and the genera Chrysochloris and Chlorotalpa as traditionally used. Carpitalpa arendsi is the sister taxon to Neamblysomus ; together, they compose the sister clade of Amblysomus. Unexpectedly, Calcochloris obtusirostris is the sister taxon of Chrysospalax. The oldest divergence within crown Chrysochloridae is likely to be the node separating Eremitalpa–Huetia or Eremitalpa alone from the remaining species. A Chrysochloris–Cryptochloris root appears most frequently under equally weighted parsimony or with few or no sampled tenrecids, suggesting that it is artefactual. The tropical genus Huetia is among the most widely distributed and anatomically polymorphic in our sample. Eremitalpa and Huetia have a relatively unspecialized hyoid apparatus and short angular process of the dentary. These elements in Huetia show a particular resemblance to those of the Namibian fossil Namachloris , which we reconstruct as a stem chrysochlorid. Crown chrysochlorids are geologically younger than crown tenrecids and probably diversified in the Miocene around the same time as the tenrecid genus Microgale. Fossils of both groups from Eocliff in Namibia are probably late Eocene to early Miocene in age. [ABSTRACT FROM AUTHOR]

IntroductionCrested chickens show abnormalities in their anatomy of the skull, endocranium, and brain (including cerebral elongation) and can be appropriate model systems for neuroanatomical evolution, brain–skull integration, and skull and brain deformities. Here, we give a detailed comprehensive description of the skull of crested chickens using the example of the Padovana chicken, including ontogenetic aspects and an allometric analysis of their brain size.MethodsIn total, 109 chickens of two different strains of the Padovana chicken were hatched together. All animals were X-rayed weekly during growth. Nine juvenile (ready for hatch) and 22 adult skulls were processed for histology and morphological descriptions, and a further 20 individuals were processed for brain analysis.ResultsAt hatching, all chicks were already crested, and a distinctive bony protuberance was first observed at the age of 4 weeks. Juvenile chickens exhibit either an open neurocranium or a protuberance. In the adult skull, foramina of different sizes can be found in the frontal bone, but no completely open neurocrania are observed in juveniles. Particularly in Padovana with cranial protuberances, several peculiarities can be observed in the os mesethmoidale, os nasale, os praemaxillare, orbit, and cranial fossae. Additionally, the brain of Padovana with cranial protuberances looks drawn in length with the shape of an hourglass and showed significantly larger encephalization indices than plain-headed breeds, topped only by another crested chicken breed.DiscussionInvestigations on chickens with cerebral elongation may facilitate the understanding of skull and brain dysplasia and may provide meaningful insights into cerebral hernia development. Additionally, crested breeds, combined with standard chickens, form a promising comparative system for investigating the emergence of novel brain and skull morphologies.

Feeding efficiency of mammalian herbivores is associated with skull traits known to differ between feeding guilds. As climate is known to affect the architecture and functional traits of plants, skull morphology may change as plant traits change along climate gradients. We tested whether skull traits of more than 70% of the extant bovid and cervid species are related to aridity, and whether these relationships differ across feeding guilds (browser, grazer, mixed feeder). We used muzzle width to represent food ingestion and masseteric fossa length to represent oral processing. For the models without phylogeny, both muzzle width and masseteric fossa length increased towards wetter climates for grazers, but not for mixed feeders or browsers. These patterns suggest that grazer diets may change more dramatically across aridity gradients than the other two groups, possibly linked to changes in both the architecture and toughness of grasses. In models accounting for phylogeny, no changes in either trait across aridity gradient were found, which appeared to be due to subfamily differentiation along the aridity gradient. Our results suggest that deeper insights into the evolution of herbivore skulls may be achieved by using quantified diet data to directly test plant trait effects on skull morphology. [ABSTRACT FROM AUTHOR]

Urocordylids represent a group of the late Carboniferous–early Permian basal tetrapods, with short limbs, extremely elongated bodies and a deep and distinctive tail and vertebral architecture, which is indicative of an aquatic habitat. However, the important morphological structures that would indicate their ecological preferences unambiguously (e.g. hyobranchial apparatus, lateral line sulci) remain unknown. Moreover, the high degree of skeletal ossification present in urocordylids contrasts with the common pattern seen in most other basal tetrapods known to inhabit aquatic environments. Here, we describe an exceptionally well-preserved skull, with an associated mandible and a partial postcranial skeleton, of Sauropleura scalaris from the locality of Nýřany, Czech Republic, based on high-resolution micro-computed tomography. The labial surface of the mandible shows the first evidence of the lateral line system in Urocordylidae, which consists of both small pits and elongated grooves, and unambiguously supports the aquatic ecology of the group. The juvenile stage of the specimen provides new information on ontogeny of sauropleurines. The partly ossified opisthotic bone indicates that, unlike development in most other early tetrapods, the otic capsules were among the first neurocranial elements to ossify in nectrideans. Finally, an almost complete caudal region suggests that tails were much longer in sauropleurines than previously assumed. [ABSTRACT FROM AUTHOR]

The unsolved problem in three-dimensional surgical planning for patients with facial deformity, dysgnathia, or asymmetry is the lack of a normative database of "norm skulls" that can be used as treatment objectives. A study was conducted on 90 Eurasian persons (46 male and 44 female adults) for whom cone beam-computed tomography images were available. Inclusion criteria were adult patients with a skeletal Class I pattern, proper interincisal relationship with normal occlusion, the absence of an open bite both in the anterior and posterior region, and a normal and balanced facial appearance; patients with dysgnathia and malformations were excluded. A total of 18 landmarks were digitized and 3D cephalometric measurements were performed and analyzed by means of proportions calculated from the landmarks. Male and female skulls were analyzed, as well as subdivisions revealed by cluster analysis. The data showed that four subtypes of skulls were distinguishable with statistical significance (p < 0.05). A male and a female type subdivided in a brachiocephalic and dolichocephalic phenotype could be identified. For each type, a mean shape was calculated by a Procrustes transformation, which, in turn, was used to create four template skulls from a male and a female skull. This was accomplished by fitting the polygon models of the two skulls to each of the two subtypes based on the landmarks marked on them using a thin plate spline transformation. The normative data of the subtypes can individually serve as a guide for orthodontic surgery in the Eurasian population, which is especially helpful in 3D planning and the execution of craniofacial operations. [ABSTRACT FROM AUTHOR]

In recent decades, the application and adaptation of new technologies have gradually become invaluable in education. When the students are visually impaired, the use of these technologies becomes even more valuable. In this line, a theoretical-practical workshop on human evolution was carried out with 25 students from the Spanish National Organisation for the Blind. Twenty-two realistic replicas of skulls of the main species in human evolution were reproduced with a 3D-FDM printer. Thus, the students were able to learn about the variability of cranial anatomy between species as we could verify with a test to evaluate the usefulness of the technology as a complement to the theoretical explanation. The results were analysed taking into account the sex and age of the students, their educational level, their degree of blindness and previous knowledge of the subject. It showed that the use of 3D models is an excellent support to the teaching-learning process in the case of the visually impaired, since it allows them to form in their imagination a faithful image of the object they hold in their hands, to feel the similarities and morphological differences between the species and to formulate hypotheses about the reasons for them. [ABSTRACT FROM AUTHOR]

Rhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically. The anatomy of the Middle Triassic forms is debated in certain phylogenetically important details. Among several genera from the Anisian of England, Bentonyx sidensis is represented by a near-complete skull. New CT scanning of the holotype skull reveals previously concealed details of the palate and braincase in particular, and this allows comparison with other Middle Triassic rhynchosaurs and confirmation that Bentonyx is a distinct taxon from others of similar age including Fodonyx, Rhynchosaurus, Langeronyx, and Stenaulorhynchus. These are part of the first wave of rhynchosaur diversification in the Middle Triassic. [ABSTRACT FROM AUTHOR]

The Triassic basal sauropodomorph Plateosaurus trossingensis is well-known from mass accumulations at the German localities of Trossingen and Halberstadt and the Swiss locality of Frick, and is significant especially regarding its taphonomy and proposed developmental plasticity. These implications, however, rely on the assumption that this material derives from a single species, which has been questioned. Here we describe new skull material from Frick including eight complete and six partial skulls, more than doubling the number of known skulls of P. trossingensis. This exceptional sample size allows for gaining a deeper understanding of variability that may occur in a single species. The new material includes the first known juvenile skulls of Plateosaurus, allowing for detecting ontogenetic changes. An attempt is made to distinguish between variability caused by taphonomic plastic deformation and intraspecific variability. Plastic deformation may shorten, but not widen bones. A number of characters commonly included in phylogenetic analyses of basal sauropodomorphs are shown to be variable within P. trossingensis, and possibly require re-evaluation. Although P. trossingensis skulls are highly variable, many of the variable characters include intermediate character states and therefore are continuous. No groupings based on skull features, locality, or stratigraphy are apparent. Consequently, the analyzed skull material from the bonebeds of Frick, Trossingen, and Halberstadt bears no evidence for the presence of more than one species.

Extant baleen whales (Mysticeti) have a deciduous foetal dentition, but are edentulous at birth. Fossils reveal that the earliest mysticetes possessed an adult dentition. Aetiocetids, a diverse clade of Oligocene toothed mysticetes, have a series of small palatal foramina and associated sulci medial to the postcanine dentition. The openings have been homologized with lateral palatal foramina that transmit neurovascular structures to baleen in extant mysticetes, thereby implying a co-occurrence of teeth and baleen in aetiocetids. However, homology of the foramina and sulci have been questioned. Using CT-imaging, we report that the lateral palatal foramina of Aetiocetus weltoni are connected internally to the superior alveolar canal, which transmits neurovascular structures to baleen in extant mysticetes and to teeth in extant odontocetes. Furthermore, the lateral palatal foramina of Aetiocetus are separate from the more medially positioned canals for the greater palatine arterial system. These results provide critical evidence to support the hypothesis that the superior alveolar neurovasculature was co-opted in aetiocetids and later diverging mysticetes to serve a new function associated with baleen. We evaluate competing hypotheses for the transition from teeth to baleen, and explore the transition from raptorial feeding in early mysticetes to filter-feeding in extant species. [ABSTRACT FROM AUTHOR]

Taeniolabis taoensis is an iconic multituberculate mammal of early Paleocene (Puercan 3) age from the Western Interior of North America. Here we report the discovery of significant new skull material (one nearly complete cranium, two partial crania, one nearly complete dentary) of T. taoensis in phosphatic concretions from the Corral Bluffs study area, Denver Formation (Danian portion), Denver Basin, Colorado. The new skull material provides the first record of the species from the Denver Basin, where the lowest in situ specimen occurs in river channel deposits ~730,000 years after the Cretaceous-Paleogene boundary, roughly coincident with the first appearance of legumes in the basin. The new material, in combination with several previously described and undescribed specimens from the Nacimiento Formation of the San Juan Basin, New Mexico, is the subject of detailed anatomical study, aided by micro-computed tomography. Our analyses reveal many previously unknown aspects of skull anatomy. Several regions (e.g., anterior portions of premaxilla, orbit, cranial roof, occiput) preserved in the Corral Bluffs specimens allow considerable revision of previous reconstructions of the external cranial morphology of T. taoensis. Similarly, anatomical details of the ascending process of the dentary are altered in light of the new material. Although details of internal cranial anatomy (e.g., nasal and endocranial cavities) are difficult to discern in the available specimens, we provide, based on UCMP 98083 and DMNH.EPV 95284, the best evidence to date for inner ear structure in a taeniolabidoid multituberculate. The cochlear canal of T. taoensis is elongate and gently curved and the vestibule is enlarged, although to a lesser degree than in Lambdopsalis. [ABSTRACT FROM AUTHOR]

Comparative osteological analyses of extant organisms provide key insight into major evolutionary transitions and phylogenetic hypotheses. This is especially true for snakes, given their unique morphology relative to other squamates and the persistent controversy regarding their evolutionary origins. However, the osteology of several major snake groups remains undescribed, thus hindering efforts to accurately reconstruct the phylogeny of snakes. One such group is the Atractaspididae, a family of fossorial colubroids. We herein present the first detailed description of the atractaspidid skull, based on fully segmented micro‐computed tomography (micro‐CT) scans of Atractaspis irregularis. The skull of Atractaspis presents a highly unique morphology influenced by both fossoriality and paedomorphosis. This paedomorphosis is especially evident in the jaws, palate, and suspensorium, the major elements associated with macrostomy (large‐gaped feeding in snakes). Comparison to scolecophidians—a group of blind, fossorial, miniaturized snakes—in turn sheds light on current hypotheses of snake phylogeny. Features of both the naso‐frontal joint and the morphofunctional system related to macrostomy refute the traditional notion that scolecophidians are fundamentally different from alethinophidians (all other extant snakes). Instead, these features support the controversial hypothesis of scolecophidians as "regressed alethinophidians," in contrast to their traditional placement as the earliest‐diverging snake lineage. We propose that Atractaspis and scolecophidians fall along a morphological continuum, characterized by differing degrees of paedomorphosis. Altogether, a combination of heterochrony and miniaturization provides a mechanism for the derivation of the scolecophidian skull from an ancestral fossorial alethinophidian morphotype, exemplified by the nonminiaturized and less extreme paedomorph Atractaspis. [ABSTRACT FROM AUTHOR]

The Triassic basal sauropodomorph Plateosaurus trossingensis is well-known from mass accumulations at the German localities of Trossingen and Halberstadt and the Swiss locality of Frick, and is significant especially regarding its taphonomy and proposed developmental plasticity. These implications, however, rely on the assumption that this material derives from a single species, which has been questioned. Here we describe new skull material from Frick including eight complete and six partial skulls, more than doubling the number of known skulls of P. trossingensis. This exceptional sample size allows for gaining a deeper understanding of variability that may occur in a single species. The new material includes the first known juvenile skulls of Plateosaurus, allowing for detecting ontogenetic changes. An attempt is made to distinguish between variability caused by taphonomic plastic deformation and intraspecific variability. Plastic deformation may shorten, but not widen bones. A number of characters commonly included in phylogenetic analyses of basal sauropodomorphs are shown to be variable within P. trossingensis, and possibly require re-evaluation. Although P. trossingensis skulls are highly variable, many of the variable characters include intermediate character states and therefore are continuous. No groupings based on skull features, locality, or stratigraphy are apparent. Consequently, the analyzed skull material from the bonebeds of Frick, Trossingen, and Halberstadt bears no evidence for the presence of more than one species. [ABSTRACT FROM AUTHOR]

Choristoderes are extinct neodiapsid reptiles that are well known for their unusual cranial anatomy, possessing an elongated snout and expanded temporal arches. Although choristodere skulls are well described externally, their internal anatomy remains unknown. An internal description was needed to shed light on peculiarities of the choristodere skull, such as paired gaps on the ventral surface of the skull that may pertain to the fenestra ovalis, and a putative neomorphic ossification in the lateral wall of the braincase. Our goals were: (i) to describe the cranial elements of Champsosaurus lindoei in three dimensions; (ii) to describe paired gaps on the ventral surface of the skull to determine if these are indeed the fenestrae ovales; (iii) to illustrate the morphology of the putative neomorphic bone; and (iv) to consider the possible developmental and functional origins of the neomorph. We examined the cranial anatomy of the choristodere Champsosaurus lindoei (CMN 8920) using high‐resolution micro‐computed tomography scanning. We found that the paired gaps on the ventral surface of the skull do pertain to the fenestrae ovales, an unusual arrangement that may be convergent with some plesiosaurs, some aistopods, and some urodeles. The implications of this morphology in Champsosaurus are unknown and will be the subject of future work. We found that the neomorphic bone is a distinct ossification, but is not part of the wall of the brain cavity or the auditory capsule. Variation in the developmental pathways of cranial bones in living amniotes was surveyed to determine how the neomorphic bone may have developed. We found that the chondrocranium and splanchnocranium show little to no variation across amniotes, and the neomorphic bone is therefore most likely to have developed from the dermatocranium; however, the stapes is a pre‐existing cranial element that is undescribed in choristoderes and may be homologous with the neomorphic bone. If the neomorphic bone is not homologous with the stapes, the neomorph likely developed from the dermatocranium through incomplete fusion of ossification centres from a pre‐existing bone, most likely the parietal. Based on the apparent morphology of the neomorph in Coeruleodraco, the neomorph was probably too small to play a significant structural role in the skull of early choristoderes and it may have arisen through non‐adaptive means. In neochoristoderes, such as Champsosaurus, the neomorph was likely recruited to support the expanded temporal arches. [ABSTRACT FROM AUTHOR]

Background and aims: Maxillary nerve block via greater palatine foramen (GPF) is most commonly followed procedure for many dental, oral and maxillofacial surgeries. Many standard textbooks mention location of GPF in a general way. Location of GPF with respect to fixed bony landmarks has been studied by many authors in different population groups. The results of those studies showed lot of variability in location of GPF. The data regarding possible existence of sexual dimorphism are sparse. The present study was aimed at contributing further data regarding morphometry of the GPF. An attempt has also been made to look for sexual dimorphism. Material and Methods: One hundred and twenty three adult dry skulls of known sex (male- 55 & female - 68) were studied for GPF with regards to- morphometry, shape, relation to molars, fixed bony landmarks- Median maxillary suture(MMS), Incisive fossa(IF), Posterior border of hard palate(PBHP), Angle between line joining GPF with IF & MMS, direction of opening of GPF into oral cavity. Results: Antero-posterior diameter on left side (p-0.006), transverse diameter on both sides (p-0.000 on left & right side) distance between GPF to IF on both sides (p- 0.013 right side, p-0.02 left side, GPF-PBHP distance on both sides (p-0.001 left side, p-0.002 on right side) showed statistical significance when compared male with female skulls. In both male and female skulls, Oval shape predominated followed by round and slit variety of GPF. Both on right and left side GPF found to be predominantly related to anterior half of 3 rd molar. Direction of opening of GPF into oral cavity was predominantly antero-medial on both sides in male and female skulls. Conclusion: Our study provides a valuable addition to the available literature on location of GPF and also gives an insight to the possible existence of sexual dimorphism.

Water buffaloes and cattle differ considerably with respect to the anatomy of the head. As a result, captive bolt stunners often fail to reliably produce adequate loss of consciousness in water buffaloes and, thus, do not fulfill animal welfare requirements. The goal of the present study was to assess and validate a new stunning device for water buffaloes meeting animal welfare and occupational safety requirements. The newly designed bullet casing gun uses .357 Mag/10.2 g hollow point bullets and has additional safety features. Its effectiveness and usability were assessed under practical conditions in an abattoir as based on widely accepted criteria. Stunning resulted in deep unconsciousness in 19 out of 20 water buffaloes. One 9-year old male did not immediately collapse. Except for very old bulls, the device presented herewith provides a means to stun water buffaloes of both sexes effectively and reliably while keeping occupational hazards to a minimum. [ABSTRACT FROM AUTHOR]

Skulls of 65 American minks from the West Pomeranian Province were examined (farm: n = 33, male: n = 16, female: n = 17; wild: n = 32, male: n = 20, female: n = 12). Craniometric parameters in the number of 24 were determined and measured on each skull. Results were averaged and compared, maintaining the division into sex groups. Males were found to have statistically significant differences between wild and farm animals in 20 parameters; measurements showing no statistically significant differences were: nasal length, postorbital constriction, brain case height and greatest height of the mandibular body. Females were found to have statistically significant differences between wild and farm animals in 6 parameters: condylobasal length, tooth row length, greatest length of the mandible, brain case basis length, postorbital length and palatal length. The percentage conversion of measurements into the greatest length of the skull showed differences in its proportions. Among male skulls, the parameters for which the ratio of differences was more than 2% were palatal length, zygomatic breadth and brain case height. For female skulls, no craniometric parameters showed differences in the skull proportions being greater than 2%. The occurrence of measurable changes in the craniometric parameters between domestic and farm mink populations may indicate that the domestication process is still ongoing and allows distinguishing the population affiliation of an individual specimen. [ABSTRACT FROM AUTHOR]

In early tetrapods, it is assumed that the tympana were acoustically coupled through the pharynx and therefore inherently directional, acting as pressure difference receivers. The later closure of the middle ear cavity in turtles, archosaurs, and mammals is a derived condition, and would have changed the ear by decoupling the tympana. Isolation of the middle ears would then have led to selection for structural and neural strategies to compute sound source localization in both archosaurs and mammalian ancestors. In the archosaurs (birds and crocodilians) the presence of air spaces in the skull provided connections between the ears that have been exploited to improve directional hearing, while neural circuits mediating sound localization are well developed. In this review, we will focus primarily on directional hearing in crocodilians, where vocalization and sound localization are thought to be ecologically important, and indicate important issues still awaiting resolution. This article is part of a Special Issue entitled < Annual Reviews 2015 > . [ABSTRACT FROM AUTHOR]

Chironius is one of the most speciose genera of the South American colubrid snakes. Although the genus represents a well-known radiation of diurnal racers, its monophyly, affinities with other Neotropical colubrid genera, and intrageneric relationships are open questions. Here, we present a phylogenetic analysis of Chironius based on a data matrix that combines one nuclear ( c-mos) and two mitochondrial ( 12S and 16S rRNA) genes with 37 morphological characters derived from scutellation, skull, and hemipenial features. Phylogenetic relationships were inferred using maximum parsimony ( MP) and maximum likelihood ( ML). Our combined morphological and molecular analyses strongly support the monophyly of the genus Chironius and its sister-group relationship with a clade formed by the genera Dendrophidion and Drymobius. Phylogenetic relationships within the genus Chironius is still controversial, although five clades are retrieved with medium to strong support. © 2014 The Linnean Society of London [ABSTRACT FROM AUTHOR]

Abstract: The Early Permian mesosaurids are the oldest known aquatic amniotes with an exclusively Gondwanan distribution. Although several hundred of complete skeletons have been discovered and intensively studied, the anatomy and taxonomic composition of the group, as well as its phylogenetic relationships remain controversial. Several well-preserved mesosaurid specimens found in Uruguay justify a new anatomical reconstruction of the skull of Mesosaurus tenuidens, differing from earlier ones especially in the presence of a lower temporal fenestra. The significance of this structure for the evolution of temporal fenestration in amniotes is evaluated according to the two most recent phylogenetic hypotheses, in which mesosaurids are basalmost sauropsids or basalmost parareptiles. A synapsid-like fenestration may be the primitive condition for Amniota, and it may be also a basal condition for parareptiles, because recent phylogenies suggest a basal position for mesosaurids and lanthanosuchoids within that group, and both possess a lower temporal fenestra. Our results also give a moderately strengthened support for diapsid affinities of turtles. [Copyright &y& Elsevier]

Abstract: Octodontoidea is the most diverse group of caviomorph rodents. The systematics of most of the fossil representatives has been essentially based upon dental characters. Described here is an almost complete skull with dentition assigned to Prospaniomys Ameghino based upon its dental morphology. The specimen comes from the Sarmiento Formation at Pampa de Gan Gan (central Patagonia, Argentina), assigned to the Colhuehuapian SALMA (early Miocene). The most remarkable features are in the posterior portion of the skull, some of them shared with the modern octodontids and interpreted as specialized by previous authors, which contrast with the generalized dental morphology. These combined features were not previously known in other octodontoids. The comparisons with other fossil and extant members of the superfamily suggest that the characters traditionally used to associate Prospaniomys with the echimyids are very probably plesiomorphies. Prospaniomys would represent an early diverging lineage more closely related to modern octodontids than to echimyids, in which cranial structures evolved more rapidly than dental and mandibular ones. [Copyright &y& Elsevier]

Uropeltid snakes are among the most poorly understood clades within Alethinophidia. Their small size, limited geographic distribution, high incidence of endemism, and fossorial behaviour all contribute to the general paucity of systematic collections of these snakes, especially of adequate skeletal preparations, in most museum collections. Their hypothesized position within the higher-order phylogeny of alethinophidian snakes calls attention to the need for additional morphological work on the group. Hypotheses of uropeltid phylogenetic relationships based on morphological analyses are few, and continue to be hampered by limited taxon-sampling and character matrices that rely predominantly on features that are visible on articulated skulls. We utilized high-resolution X-ray computed tomography (HRCT) to investigate the cranial osteology of Plectrurus aureus Beddome, 1880, a species for which no osteological data were previously available. We provide a detailed description of the skull and mandible, and comment on morphological characters and potential phylogenetic relationships. Clarity in character descriptions is of paramount importance, and additional morphological characters are desirable. HRCT provides a nondestructive way to identify new systematically informative morphological characters from digitally disarticulated specimens. The small size of many uropeltid species, including P. aureus, will help to frame a greater appreciation of the limitations of traditional HRCT protocols for revealing detailed anatomical features of small vertebrates. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160, 118–138. [ABSTRACT FROM AUTHOR]

The present study measured the position of the greater palatine foramen relative to adjacent anatomical landmarks in Brazilian skulls. The perpendicular distance of the greater palatine foramen to the midline maxillary suture in Brazilian skulls was about 14 mm and the distance of greater palatine foramen to the incisive foramen was approximately 36 mm. The distance of greater palatine foramen to the posterior border of the hard palate was approximately 3 mm, and the mean angle between the midline maxillary suture and the line from the incisive foramen and the greater palatine foramen was 22.71°. In almost 70% of the cases, the greater palatine foramen opened in an anterior direction. The mean palatine length was approximately 52 mm. In the greater majority of the skulls (93.81%), the greater palatine foramina were opposite or distal to the maxillary third molar. These data will be helpful in comparing these skulls to those from various other regions as well as comparing skulls of different races. It can also provide professionals with anatomical references, in order to block the maxillary division of the trigeminal nerve through the greater palatine foramen. Our results would help clinicians locate the greater palatine foramen in patients with and without upper molars. [ABSTRACT FROM AUTHOR]

Detailed description of the cranial anatomy of the rhynchosaur previously known as Scaphonyx sulcognathus allows its assignment to a new genus Teyumbaita. Two nearly complete skulls and a partial skull have been referred to the taxon, all of which come from the lower part of the Caturrita Formation, Upper Triassic of Rio Grande do Sul, southern Brazil. Cranial autapomorphies of Teyumbaita sulcognathus include anterior margin of nasal concave at midline, prefrontal separated from the ascending process of the maxilla, palatal ramus of pterygoid expanded laterally within palatines, dorsal surface of exoccipital markedly depressed, a single tooth lingually displaced from the main medial tooth-bearing area of the maxilla, and a number of other characters (such as skull broader than long; a protruding orbital anterior margin; anguli oris extending to anterior ramus of the jugal; bar between the orbit and the lower temporal fenestra wider than 0??4 of the total orbital opening; mandibular depth reaching more than 25 of the total length) support its inclusion in Hyperodapedontinae. T. sulcognathus is the only potential Norian rhynchosaur, suggesting that the group survived the end-Carnian extinction event. [ABSTRACT FROM PUBLISHER]

Background Context: The halo skeletal fixator provides the most rigid type of immobilization of all the orthoses that stabilize the cervical spine. Sometimes with older patients (>70 years old), the pin penetrates the cortical and cancellous bone of the skull and enters the intracranial space, which can result in serious complications such as brain injury, infection, hematoma, and loss of cerebrospinal fluid from the subarachnoid space. Currently, there is a lack of relevant literature that examines these concerns. Purpose: To evaluate the thickness of the outer table, diploe, and inner table at the anterolateral and posterolateral pin insertion areas of the skull in elderly cadavers by using computed tomography (CT) scans. In addition, insertion torques at the four standard pin insertion areas was determined by applying halo pins at incremental torque in an effort to suggest safe torque levels for the anterolateral and posterolateral pins. Study Design/setting: A human cadaveric anatomical and biomechanical study relating to thickness and insertion torques at standard pin areas in the elderly. Patient Sample: Twenty-one elderly cadaveric skull specimens. Outcome Measures: Thickness of cortices (tables) and diploe of skull and insertion torque at halo pin insertion areas. Methods: Aquarius Image software at the CT scanner's TeraRecon Aquarius Workstation was used to make the necessary skull thickness measurements at the pin insertion areas. Six, 8, 12, 18, and 36 inch lb of torque were used to determine penetration of the pins through the inner table at each of the four locations (two anterolateral and two posterolateral). Results: The mean anterolateral thickness was 7.36+/-1.57 mm. The average thickness of the outer table, diploe, and inner table were 2.24+/-0.44 mm, 1.52+/-0.41 mm, and 3.59+/-1.70 mm, respectively. The mean posterolateral thickness was 9.47+/-1.12 mm. The average thickness of the outer table, diploe, and inner table were 4.32+/-0.92 mm, 1.88+/-0.35 mm, and 3.27+/-1.21 mm, respectively. No pin penetration was seen at the traditional 8 inch lb of insertion torque in both the anterolateral and posterolateral pin insertion areas. Eighteen inch lb of torque resulted in penetration in 90.48% (19/21) and in 85.71% (18/21) of specimens in the left anterolateral and right anterolateral pin insertion areas, respectively. No penetration was seen even at 36 inch lb of torque in 80.95% (17/21) of the cadavers in both the left and right posterolateral pin insertion areas. Conclusions: The current study supported previous research that 8 inch lb of torque is safe for application of halo pins in the elderly. The posterolateral skull is thicker and stronger than the anterolateral skull. The safe maximum torque is 8 inch lb for anterolateral pin insertion area and 18 inch lb for the posterolateral pin insertion area. [ABSTRACT FROM AUTHOR]

In view of their propositional content (i.e. they can be right or wrong), character statements (i.e. statements that predicate characters of organisms) are treated as low-level hypotheses. The thesis of the present study is that such character statements, as do more complex scientific theories, come with variable scope. The scope of a hypothesis, or theory, is the domain of discourse over which the hypothesis, or theory, ranges. A character statement is initially introduced within the context of a certain domain of discourse that is defined by the scale of the initial phylogenetic analysis. The doctrine of ‘total evidence’ requires the inclusion of previously introduced characters in subsequent studies. As a consequence, the initial scope of character statements is widened to the extent that the scale of subsequent analyses is broadened. Scope expansion for character statements may result in incomplete characters, in the subdivision of characters, or in ambiguity of reference (indeterminacy of the extension of anatomical terms). Character statements with a wide scope are desirable because they refer to characters with the potential to resolve deep nodes in phylogenetic analyses. Care must be taken to preserve referential unambiguity of anatomical terms if the originally restricted scope of a character statement is expanded to match a broad-scale phylogenetic analysis. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 297–308. [ABSTRACT FROM AUTHOR]

Snakes-a subset of lizards-have traditionally been divided into two major groups based on feeding mechanics: "macrostomy," involving the ingestion of proportionally large prey items; and "microstomy," the lack of this ability. "Microstomy"-considered present in scolecophidian and early-diverging alethinophidian snakes-is generally viewed as a symplesiomorphy shared with non-snake lizards. However, this perspective of "microstomy" as plesiomorphic and morphologically homogenous fails to recognize the complexity of this condition and its evolution across "microstomatan" squamates. To challenge this problematic paradigm, we formalize a new framework for conceptualizing and testing the homology of overall character complexes, or "morphotypes," which underlies our re-assessment of "microstomy." Using micro-computed tomography (micro-CT) scans, we analyze the morphology of the jaws and suspensorium across purported "microstomatan" squamates (scolecophidians, early-diverging alethinophidians, and non-snake lizards) and demonstrate that key components of the jaw complex are not homologous at the level of primary character state identity across these taxa. Therefore, rather than treating "microstomy" as a uniform condition, we instead propose that non-snake lizards, early-diverging alethinophidians, anomalepidids, leptotyphlopids, and typhlopoids each exhibit a unique and nonhomologous jaw morphotype: "minimal-kinesis microstomy," "snout-shifting," "axle-brace maxillary raking," "mandibular raking," and "single-axle maxillary raking," respectively. The lack of synapomorphy among scolecophidians is inconsistent with the notion of scolecophidians representing an ancestral snake condition, and instead reflects a hypothesis of the independent evolution of fossoriality, miniaturization, and "microstomy" in each scolecophidian lineage. We ultimately emphasize that a rigorous approach to comparative anatomy is necessary in constructing evolutionary hypotheses that accurately reflect biological reality., (© 2021 American Association for Anatomy.)

Abstract: Objective: To investigate the anatomical variability of the palatine structures in Greek population. Material and methods: 71 Greek adult dry human skulls were examined to detect the position of the greater palatine (GPF) and lesser palatine foramina (LPF) related to adjacent anatomical landmarks. Results: The perpendicular distance of the GPF to the midline sagittal suture was 1.53cm and 0.3cm from the inner border of the alveolar ridge. The mean distance from the posterior palatal border was consistent 0.46cm on the right and 0.47cm on the left side of the skulls. In the greater majority of the skulls (76.2%), the GPF were between proximal–distal surfaces of the 3rd maxillary molar. A single LPF was observed in 53.45% of the skulls, two LPF were observed in 31% of the skulls bilaterally and five LPF were rare (2.1%). The commonest position of LPF was at the junction of the palatine bone and the inner lamella of the pterygoid plate (71.9%). Conclusion: Our results can help clinicians localize the palatine foramina in patients with and without maxillary molars and to predict the depth of a needle to anaesthetise the maxillary nerve with greater success when performing surgical procedures in the hard and soft palate. [Copyright &y& Elsevier]