The morphology of the lower jaw and teeth of the legless lizard Pseudopus apodus (Anguimorpha, Anguidae, Anguinae) from Eurasia are described in detail and compared with those of other species of the subfamily Anguinae. The lower jaw anatomy of Pseudopus, especially the dentary and teeth, clearly differs from the genera Ophisaurus and Anguis. Even so, Ophisaurus is largely uniform in its lower jaw morphology across species. The teeth of North American Ophisaurus are slender cylinders, the shafts are mesiodistally compressed and bulge lingually; the apices are curved lingually and posteriorly and have weakly developed cutting edges. Southeast Asian and North African Ophisaurus present conical teeth, with broadened bases, apices more distinctly curved lingually and posteriorly, and cutting edges that are distinctly developed. The lingual surfaces of the tooth apices are striated in Ophisaurus and Pseudopus. The lower jaw of Ophisaurus is in many respects similar to that in Anguis, however, the teeth of Anguis are longer and markedly curved posteriorly. The result of the phylogenetic analysis rendered six equally parsimonious trees. Anguis appears in three alternative positions, as the sister taxon to a clade formed by Ophisaurus and Pseudopus, as the sister taxon of Ophisaurus, or as forming a clade with Ophisaurus which is the sister group to Pseudopus. Anat Rec,

The origin of amniotes was a key event in vertebrate evolution, enabling tetrapods to break their ties with water and invade terrestrial environments. Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Using high-resolution X-ray microcomputed tomography, we reveal the three-dimensional architecture of the well preserved endosseous labyrinth of the inner ear in representative species belonging to both groups. Data from the inner ear are coded in a new cladistic matrix of stem and primitive crown amniotes. Both maximum parsimony and Bayesian inference analyses retrieve seymouriamorphs as derived non-crown amniotes and diadectomorphs as sister group to synapsids. If confirmed, this sister group relationship invites re-examination of character polarity near the roots of the crown amniote radiation. Major changes in the endosseous labyrinth and adjacent braincase regions are mapped across the transition from non-amniote to amniote tetrapods and include: a ventral shift of the cochlear recess relative to the vestibule and the semicircular canals; cochlear recess (primitively housed exclusively within the opisthotic) accommodated within both the prootic and the opisthotic; development of a distinct fossa subarcuata. The inner ear of seymouriamorphs foreshadows conditions of more derived groups, whereas that of diadectomorphs shows a mosaic of plesiomorphic and apomorphic traits, some of which are unambiguously amniotelike, including a distinct and pyramid-like cochlear recess.

Pseudopus apodus (Pallas, 1775) is the largest extant legless species of the subfamily Anguinae (Anguimorpha, Anguidae) living mostly in the sub-arid territories ranging from the Balkan area in Europe to Kazakhstan in Asia. The species of other two genera live in North America, South-East Asia and North Africa (Ophisaurus) and Europe and South-West Asia (Anguis). The interrelationships of Anguinae are unresolved; this is in part the consequence of the insufficient knowledge of the cranial, postcranial and integumentary anatomy of the individual anguine species. The aim of this article is to fulfill this gap in our knowledge of the anguine anatomy. Now, in the first part of the project, the individual bones of the exocranium and visceral endocranium of the anguine legless lizard P. apodus are described in detail. In the present study, P. apodus is revealed to have autoapomorphic features of the skull which clearly distinguish it from Anguis and Ophisaurus. In addition, the study of posthatchling ontogeny of exocranium of P. apodus revealed some features, such as a nasal process of premaxilla being slightly widened in about its mid-length, that are also typical for adults of the Ophisaurus and Anguis species as well as extinct species of Pseudopus. This strongly indicates that peramorphic heterochronic process played role in the evolution of the P. apodus skull. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:460-502, 2017. © 2016 Wiley Periodicals, Inc.

In order to allow precise and detailed physical studies of an MgB2 filament made by the internal magnesium diffusion process (IMD), a modified approach (MIMD) using a Mg tube filled with boron powder deformed into wire was introduced. The MIMD process allows easy extraction of the MgB2 filament after the final heat treatment and performance of four-probe resistive measurements and density estimation, which is not possible for standard IMD wires. The Rowell approach has been applied for the grain connectivity from R(T) data of extracted MgB2 for the first time. The filament’s density has been estimated from the precise volume measured by x-ray micro-tomography and mass. The high connectivity and density of the MgB2 filament made by the diffusion process are discussed and compared with those of filaments made by other processes.

The article reports on the first detailed vertebral and rib morphology of anguine taxon Pseudopus apodus using micro-computed tomography. A comparison shows significant morphological differences of vertebrae of Pseudopus relative to those of Anguis and Ophisaurus. Usually, there are 55 presacral vertebrae, two sacral, and 95-97 caudal vertebrae. Pseudopus apodus can be defined by 23 diagnostic features concerning the vertebral column. Although zygapophyseal articulation between atlas and axis is well developed in limbed anguid gerrhonotine lizards like Abronia or Barisia, it is absent in the extant representatives of the clade Anguinae, which are limbless. Thus, our study brings further support to the hypothesis about the complete reduction of this articulation in forms with reduced or absent limbs. Comparison of adult and juvenile morphology of vertebrae of P. apodus was also analyzed. Heterochrony in the evolution of this taxon was previously confirmed by its skull morphology and it can be also documented on the basis of vertebrae. Our data suggest that a peramorphic heterochronic process played a role in the evolution of this largest extant anguine species. Geometric morphometric analyses revealed a pattern of high vertebral disparity among species. We found a clear separation of limbless forms in morphospace. Pseudopus apodus always clusters within Ophisaurus-species confirming molecular and some morphological phylogenies. Only the first tail vertebra shows a distinct difference to those of Jana Ciceková is currently affiliated with The Bridge Language Centre, Baštová 344/7, 811 03 Bratislava 1.

A detailed anatomy of the braincase and stapes of the subadult specimen of Diadectes absitus from early Permian sediments of Germany are described for the first time based on the high-resolution X-ray microcomputed tomography. In contrast to previous studies of Diadectes, the bones of the braincase (opisthotic, prootic, supraoccipital, basioccipital, exoccipital, basisphenoid, and sphenethmoid), and parasphenoid of D. absitus are not co-ossified, but suturally defined. This has allowed for a reconstruction of a complete braincase with all sutures between the individual bones. The opisthotic, prootic, and supraocciptal contain a well-preserved endosseous labyrinth. The three-dimensionalreconstruction of its cavities shows a well-preserved vestibule, three semicircular canals, and well-developed cochlear recess. In addition, a shallow subarcuate fossa is present on the ventral surface of the supraoccipital, which lies medial to the anterior semicircular canal. A typical feature of the diadectid braincase is the presence of the otic tube leading from the fenestra vestibuli to the vestibule. A revision of the topology of this structure is presented here. Here, we describe new structures of the stapes, especially in its proximal portion, as well as its position to the fenestra vestibuli. These structures are described for the first time not only in D. absitus, but for the genus.

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The braincase anatomy of the Pennsylvanian diadectomorph Limnoscelis dynatis is described in detail, based upon high-resolution X-ray microcomputed tomography. Both supraoccipitals and most of the prootics and opisthotics are preserved. The known portions of the left prootic, opisthotic, and supraoccipital enclose complete sections of the endosseous labyrinth, including the anterior, posterior, and lateral semicircular canals, the vestibule, the cochlear recess, and the canal for the endolymphatic duct. The fossa subarcuata is visible anteromedial to the anterior semicircular canal. The presumed endolymphatic fossae occur in the dorsal wall of the posteromedial portion of the supraoccipital. Both the fossa subarcuata and the fossa endolymphatica lie in the cerebellar portion of the cranial cavity. In order to investigate the phylogenetic position of L. dynatis we used a recently published data matrix, including characters of the braincase, and subjected it to maximum parsimony analyses under a variety of character weighting schemes and to a Bayesian analysis. Limnoscelis dynatis emerges as sister taxon to L. paludis, and both species form the sister group to remaining diadectomorphs. Synapsids and diadectomorphs are resolved as sister clades in ∼90% of all the most parsimonious trees from the unweighted analysis, in the single trees from both the reweighted and the implied weights analyses, as well in the Bayesian tree.