Morphology of the palate and braincase of Dimetrodon milleri

The palate and partial braincase of the holotype of Dimetrodon milleri (MCZ 1365) are preserved in three dimensions, but have yet to be described in detail. Here, we describe these structures for the first time for this species, and compare them with the better-known specimens of D. limbatus. Interesting characteristics of the morphology include the patterns of articulation of the palatal elements, including the palatine and vomer, and anatomy of the pterygoid in the posterior region of the palatal vacuities. Dimetrodon milleri is found to differ from D. limbatus in the lack of teeth on the ectopterygoid, the shape of the basal process of the epipterygoid, and the anterior extent of the palatine and pterygoid. The two species are similar in the relative position of the basicranial articulation, but differ significantly from that in other sphenacodontids, including Secodontosaurus and Sphenacodon. The evolution of these cranial features will be the subject of future phylogenetic analyses of sphenacodontids.     

The cranial and cervical osteology of the european oystercatcher Haematopus ostralegus L.

The cranial and cervical osteology of the European oystercatcher, Haematopus ostralegus L. is completely described from both whole skeletons and spirit specimens. Contrary to previous reports, the postorbital ligament shows variability in bifurcation and attachment, with the posterior branch, where present, attaching either to the suprameatic process or the zygomatic process. In addition, the quadrate ligament, which had been described as originating from the suprameatic process, appears instead to attach to the zygomatic process in some specimens. The caudal mandibular fenestra, earlier considered absent in oystercatchers, is present in all specimens examined. The cranium is additionally distinguished by a number of features which may be unique to oystercatchers. A fourth, previously unrecorded, division of the maxillopalatine strut is present, while the palatine process of the premaxilla is reduced to a thickening along the edge of the premaxillary process of the palatine. The distinctiveness of the oystercatcher cranium is particularly evident in the area of the quadratomandibular articulation, which possesses features potentially important for stabilizing the joint. A deep retroarticular notch is present, guiding a large medial jugomandibular ligament along the posterior margin of the articulation. A lateral mandibular tuberosity, which is received dorsally by an emargination of the jugal arch and quadrate, may act as an osteological brace, preventing posterior shifting of the closed mandible. The 15 cervical vertebrae are divided on the basis of structural criteria into three sections.     

Description of two new genera, Santelmoa and Bentartia and two new species of Zoarcidae (Teleostei, Perciformes) from the Southern Ocean

Two new genera of lycodine zoarcid fish, Santelmoa and Bentartia, and two new species, Santelmoa carmenae and Bentartia cinerea, are described from 13 specimens collected from the Gerlache Strait, Southern Ocean, at 1,056-m depth. Santelmoa can be distinguished from all other lycodine genera by the combination of the following characters: anterior portion of frontals fused; scapular foramen open; ceratohyal–epihyal articulation interdigitating; cranium narrowed; supratemporal commissure and occipital pores absent; intercalar reaching the prootic; parasphenoid wing well developed; palatal arch well developed; posterior hyomandibular ramus short; post-temporal ventral ramus well developed; six branchiostegal rays; vertebrae asymmetrical; pelvic fin rays ensheathed; scales, lateral line, pyloric caeca, palatine and vomerine teeth present. Bentartia differs from the remaining lycodine genera by the following combination of characters: basioccipital and exoccipitals fused; supraoccipital–exoccipital articulation broadly contacting; ceratohyal–epihyal articulation interdigitating; post-temporal ventral ramus weak; two posterior nasal pores; cranium narrowed; supratemporal commissure and occipital pores absent; intercalar set posteriorly; palatal arch well developed; posterior hyomandibular ramus not elongate; parasphenoid wing high; six branchiostegal rays; vertebrae asymmetrical; pelvic fin rays ensheathed; scales, lateral line, pyloric caeca, palatine and vomerine teeth present. The relationships of the two new genera are discussed.     

Ontogeny of the maxillary barbel muscles in Clarias gariepinus (Siluroidei: Clariidae), with some notes on the palatine-maxillary mechanism

Siluroids are characterized by the presence of a palatine-maxillary mechanism, which enables a controlled mobility of the maxillary barbels. In Clarias gariepinus , the ontogeny of this mechanism is studied and described as well as those muscles related to the maxillary barbel. Two muscles are distinguished: (1) retractor tentaculi , connecting the maxilla to the suspensorium, and (2) extensor tentaculi , running from the ventro-lateral face of the skull to the posterior half of the palatine. These typical catfish muscles are derived from muscles that are present in generalized teleost fishes. The retractor muscle is believed to be derived from the A₃ muscle of the adductor mandibulae complex. The extensor muscle is formed from the anterior fibres of the adductor arcus palatini. The palatine is rod-like in C. gariepinus and articulates with the orbitonasal lamina in larval specimens and with its ossification, the lateral ethmoid, in juvenile and adult specimens. The articulation occurs via a long cartilaginous strip on the dorsal face of the autopalatine, thereby enabling both a rotation and a restricted sliding.     

Zur Evolution basicranialer Gelenke bei Vögeln,insbesondere bei Hühner- und Entenvögeln (Galloanseres)

On the evolution of basicranial articulations of birds, especially of fowl and waterfowl (Galloanseres) Basicranial articulations are among the most neglected structures of the avian feeding apparatus. Based on the presented ontogenetic evidence two nonhomologous types of basicranial articulations are distinguished in birds: 1. A basipterygoid articulation developing from an early embryonic quadratopolar comissure, which is homologous to the basipterygoid articulation of other amniotes. This diarthrosis is present in all paleognathous as well as in many juvenile and some adult neognathous birds. 2. A rostropterygoid articulation developing through apposition of the pterygoid on the parasphenoid. This secondary articulation is known from galliform and ansenform birds (Galloanseres). Based on ontogenetic evidence as well as functional analysis following hypothesis explaining the evolution of rostropterygoid articulations in the Galloanseres is proposed: 1. In the groundplan of birds (Aves, sensu Gauthier 1986) a basipterygoid articulation was present continuously during ontogeny. It protected the pterygoid-quadrate articulation against propalineal distortion by controlling the movement of the caudal end of the flexible, but undivided pterygopalatinal bar. This construction is preserved in recent paleognaths. 2. In the groundplan of the Neognathae an intrapterygoid joint subdividing the pterygopalatinal bar was formed in juveniles. Consequently the basipterygoid articulation had lost its function in adults and was therefore developed only in embryonic and juvenile stages. This condition is present in many recent neognaths. 3. In the stemline of the Galloanseres the intrapterygoid joint was already formed in embryos. Since an undivided pterygopalatinal bar is absent in any ontogenetic stage of the Galloanseres, no basipterygoid articulation is being formed. The recent Galloanseres retain this developmental pattern. 4. In the groundplan of the Galloanseres a newly developed rostropterygoid articulation was present providing a support for the pterygopalatinal bar. This articulation could withstand not only pressure but also increasing tension occurring as a consequence of the development of a gliding jaw joint and a firm grip with beak tips, both consequences of increasing herbivory in the Galloanseres. Since the basipterygoid articulation was reduced, a new secondary joint had to be developed.     

Prey transport in "palatine-erecting" elapid snakes

Cobras and mambas are members of a group of elapid snakes supposedly united by the morphology and inferred behavior of their palatine bone during prey transport (palatine erectors). The palatine erectors investigated (Dendroaspis polylepis, Naja pallida, Ophiophagus hannah, Aspidelaps scutatus, A. lubricus) show differences in the morphology of their feeding apparatus that do not affect the overall behavior of the system. We delineated the structures directly involved in producing palatine erection during prey transport. Palatine erection can be achieved by a colubroid muscle contraction pattern acting on a palato-pterygoid bar with a movable palato-pterygoid joint and a palatine that is stabilized against the snout. The palatine characters originally proposed to cause palatine erection are not required to produce the behavior and actually impede it in Naja pallida. Palatine-erecting elapids share a fundamental design of the palato-maxillary apparatus with all higher snakes. A set of plesiomorphic core characters is functionally integrated to function in prey transport using the pterygoid walk. Variant characters are either part of a structural periphery unrelated to the core structures that define function or patterns of variation are subordinate character sets operating within functional thresholds of a single system.     

Skeletal morphology of the mud star,Ctenodiscus crispatus (Echinodermata: Asteroidea)

The morphology of the following eight major ossicle types is described and illustrated for the goniopectinid asteroid Ctenodiscus crispatus: terminal plates, superomarginal and inferomarginal ossicles, adambulacral and ambulacral ossicles, odontophores, oral intermediate plates, and superambulacral ossicles. Development, variation, and relationships with soft body-parts and with other ossicles are embphasized. Each ossicle type is distinguished by numerous structures related to its function and to articulation with adjoining skeletal elements. Because major structures (such as pustules, alveoli, and articulation surfaces) distinguishing ossicle types develop early during ontogeny, immature ossicles are readily identifiable. However, changes in form and orientation of these structures occur during ossicle growth. Ontogenetic changes are influenced by development of associated skeletal and soft parts. Ambulacral and adambulacral ossicles near the peristome are highly modified but retain the basic characteristics of structure and orientation which define these major types of skeletal elements.     

昆都仑鱼(Kuntulunia)的新材料及其系统位置的讨论

本文根据对宁夏六盘山群马东山组的长鳍昆都仑鱼(Kuntulunia longipterus, Liu, Ma et Liu 1982)的新材料的研究,对其形态特征做了一些补充和订正。在此基础上,笔者支持刘宪亭等人将昆都仑鱼归入华夏鱼科(Huashiidae)及华夏鱼科归入骨舌鱼类的观点。并且认为华夏鱼类代表了一新的亚目——华夏鱼亚目(Huashioidei subordo. nov.)。     

The chemical fractionation of lymphatic organs

A method for chemically fractionating lymphatic organs has been described. The method has been shown to be applicable to bovine palatine tonsils, sheep palatine tonsils, and bovine thymus. Approximately 50 per cent of the dry weight of tonsils and about 30 per cent of thymus has been found to be soluble in the 0.15 M NaCl extract. Four components have been isolated which together account for 65 per cent by weight of the material in the extracts. Four other components have been identified and partially defined by means of electrophoretic mobility, solubility, or some other chemical or physical property.     

The postorbital palatoquadrate articulation in elasmobranchs

Although modern hexanchiforms are the only extant elasmobranchs with a postorbital articulation, according to most morphological and molecular cladistic analyses they are not basal, suggesting that Huxley ( 1876 Proc Zool Soc 1876;24–59) correctly identified this articulation as “an altogether secondary connection.” A postorbital articulation is present in many Paleozoic sharks, but differs from that found in hexanchiforms in its morphology, topographic position on the braincase, and inferred ontogenetic origins. Furthermore, a postorbital articulation is absent in hybodonts (the putative extinct sister group to neoselachians). It is proposed that the term amphistylic should be restricted to the modern hexanchiform condition, where the articular facet is located on the primary postorbital process. An identical articulation probably existed in some extinct galeomorphs (e.g., ?Synechodus dubrisiensis, ?Paraorthacodus), but is not widespread within elasmobranchs generally. The term archaeostylic (“ancient pillar”) is proposed here for the suspensorial arrangement in Paleozic sharks with a postorbital articulation on the ventrolateral part of the lateral commissure. Such an articulation is not known in other gnathostomes and may represent a basal chondrichthyan synapomophy (especially if ?Pucapampella is a stem chondrichthyan), suggesting that the autodiastylic pattern is not primitive for chondrichthyans and that holocephalans have secondarily lost a postorbital articulation. The amphistylic condition may have arisen from the archaeostylic, or it could have been acquired independently within neoselachians, but in either case it is most parsimoniously viewed as apomorphic. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

The cranial osteology and hyolaryngeal apparatus of Rhinophrynus dorsalis (Anura: Rhinophrynidae) with comparisons to recent pipid frogs

The cranial osteology (including the hyolaryngeal apparatus) of Rhinophrynus dorsalis (Anura: Rhinophrynidae) is described from whole skeletons and serial cross sections. Some unique features of the extensively ossified skull include the enlarged and protracted olfactory region, for which the nasals form part of the septum nasi; the relatively short maxillaries and broad premaxillaries, and the immense quadratojugal; the extreme forward position of the quadrate; the lack of a firm articulation of the pterygoid and quadrate with the neurocranium and crista parotica; the quadrate lacking the distinct processes typical of other frogs; a single foramen for Nn. II–VII; a large, distinct operculum; and a bipartite hyale. Rhinophrynus shares other unusual cranial characteristics with the other pipoid frogs, Xenopus, Pipa, Hemipipa, and Hymenochirus. Among these features are the presence of a single frontoparietal in the adult, and the absence of parasphenoid alae, palatines, and mentomeckelian bones. Rhinophrynus differs from the pipids in the lack of a columella and a palatine process on the premaxilla, and in the possession of a quadratojugal, parahyoid bone, paired prevomers, olfactory eminence, massive quadrate that lacks distinguishable processes, a modified squamosal, and a bipartite hyale. Although the cranium of Rhinophrynus is distinctive, the evolutionary significance of its unusual features will remain obscure until comparable data are gathered from other closely related groups, the Discoglossoidea and the Pelobatoidea.     

Human palatal growth evaluated on medieval crania using nerve canal openings as references

The purpose of this investigation was to measure postnatal lengthening and widening of the hard palate by use of nerve canal openings as references. The relationship of the dentition to the greater palatine foramina was also investigated. Thirty-nine medieval dry skulls were examined, 22 from children and 17 from adults. All crania were photographed at a 1:1 scale. The dimensions of the maxilla and the location of the dentition were determined from the photographs. The study showed that palatal growth in length in the sagittal plane takes place anterior to the greater palatine foramen. The growth increment in the area between the incisive foramen and the transverse palatine suture is more pronounced than the growth increment in the area between the transverse palatine suture and the greater palatine foramen. The distance from the greater palatine foramina to the posterior margin of the palate did not increase significantly with age. The growth in width seems to continue into adult life. The first permanent molars and the surrounding bone are moved forwards in relation to the greater palatine foramina during growth. The space for the developing maxillary premolars and molars therefore has to be obtained by growth in the transverse palatine suture. © 1996 Wiley-Liss, Inc.     

The cranial arteries of turtles and their evolutionary significance

In this paper the cranial arteries, cranial arterial foramina, and bony canals of the Cheloniidae, Chelydridae, Pelomedusidae, and Chelidae are described in detail. From skull studies and published material, the general cranial arterial patterns of all the turtle families can be inferred. Sea turtles, the Cheloniidae and Dermochelyidae, possess both a large stapedial artery and a large artery supplying the orbit, which is possibly similar to the primitive cranial arterial pattern for turtles. From a primitive pattern in which stapedial and palatine arteries supply the orbit, the Chelydridae and Testudinidae retained a large stapedial artery and reduced the palatine artery, while the Kinosternidae and Dermatemydidae developed a large palatine artery and reduced the stapedial artery. The Trionychidae and probably the Carettochelyidae evolved a complex arterial pattern in which the stapedial artery was reduced somewhat and the pseudopalatine artery was substituted for the palatine artery. Pleurodires in general retained a large stapedial artery and reduced or eliminated the palatine artery. The Podocneminae, including the Madagascar species, developed a highly modified carotid canal, which is found in no other turtle group. The facts which have been presented should aid in fossil skull studies and in understanding the evolutionary background of recent turtles.     

Analysis of a control system for speech movements]

Analyzing the control quality in autonomic contour of articulation control system an account is made for the nonlinearities of the type of the zone ofunsensitivity, limitation and logarithmic response of the receptor. Regions of stablity and autooscillation frequency are determined. The role of recontrolling value is stated as a criterion of the control quality. It is suggested that the mechanisms of some stammering forms are concerned with the initiation of autooscillations in the articulation control system.     

Palatine bone in human cyclopia

In human cyclopia, a maxillopalatine mass separates the median orbit from the oral cavity. The palatine component of this bony mass has been studied in serial sections through the median third of the head in three perinatal human specimens presenting with a median orbit and proboscis. One head was sectioned in the sagittal plane and two in the coronal plane. The course of each neurovascular bundle arising from the maxillary artery and nerve was used to facilitate the identification of the various parts of the palatine bone. The data obtained were used to outline the palatine component of the maxillopalatine mass as it presented on the inferior aspect of a dried cyclops skull. The suggestion is made that the abnormalities of the palatine bone in human cyclopia are secondary to the absence of the presphenoid and the nasal cavity.     

Morphology and evolution of the ectethmoid-mandibular articulation in the meliphagidae (Aves)

The ectethmoid-mandibular articulation in Melithreptus and Manorina (Meliphagidae: Aves) consists of the dorsal mandibular process fitting into and abutting against the ventral ectethmoid fossa; it forms a brace for the mandible. This articulation in Melithreptus is a typical diarthrosis with long folded capsular walls. The mandible, thus, has two separate articulations, each with a different axis of rotation. No other genus of Meliphagidae (except Ptiloprora) or any other avian family possesses a similar feature. The jaw and tongue musculature of Melithreptus are described. The two muscles opening the jaws are well developed, while those closing the jaws are small. The tongue muscles show no special developments. A large maxillary gland, presumably muscus secreting, covers the ventral surface of the jaw muscles. Its duct opens into the oral cavity just behind the tip of the upper jaw. The frilled tip of the tongue rests against the duct opening. The ectethmoid-mandibular articulation braces the adducted mandible against dorsoposteriorly directed forces. The mandible can be held closed without a compression force exerted by the mandible on the quadrate, permitting the bird to raise its upper jaw with greater ease and less loss of force. The tongue can be protruded through the slight gap between the jaws, moving against the duct opening and thus be coated with mucus. Presumably, these birds capture insects with their sticky tongue. Hence, the ectethmoid-mandibular articulation is an adaptation for this feeding method; it evolved independently in three genera of the Meliphagidae. The ectethmoid-mandibular articulation demonstrates that a bone can have two articulations with different axes of rotation, that the two articular halves can separate widely, and that articular cartilages can be flat and remain in contact over a large area. Its function suggests that the basitemporal articulation of the mandible found in many other birds has a similar function. And it demonstrates that in the evolution of the mammalian dentary-squamosal articulation, the new hinge did not have to lie on the same rotational axis as the existing quadrate-articular hinge.     

Focal palatine erosion associated with dental malocclusion in captive cheetahs

A severe palatine disorder caused by maloccluded molars was discovered in captive adult cheetahs at the San Diego Wild Animal Park. This defect has been labeled focal palatine erosion (FPE). Subsequently, a total of 59 cheetahs from several institutions have been examined to evaluate the occurrence and etiology of this disorder. Maloccluded lower molars contacting the palatal mucosa appear to be the primary source of irritation. Infection develops when decaying food and grass particles become lodged in the resulting defect. Eventually, complete palatine perforation results which can extend into the nasal passages and eventually lead to systemic disorders. Of 59 cheetahs studied, 15 displayed various stages of FPE. Examination of 26 museum skull specimens revealed four cases of palatine perforation. These four were from a group of eight animals that were zoo raised. Focal palatine erosion appears to be a result of dietary factors. All cheetahs with FPE received a commercially prepared soft diet while in captivity. The lack of normal biting, tearing, and pulling action associated with natural prey capture and consumption could result in malocclusion caused by atrophy from disuse of the masticatory apparatus. Improper occlusion could also stem from insufficient wear or unsynchronized development of the opposing dental arches. All but two cases of FPE were found in cheetahs imported from a limited area in southwest Africa in 1970, or their offspring. Since molar size and jaw structure can be inherited, there may be genetic factors involved but more data are needed to support this idea. Treatment includes changing diet, reducing the height of the offending molar, controlling infection, eliminating irritants, and in some cases, surgical reconstruction.     

Differentiation of the palatine tonsillar tissues of the human fetus]

Differentiation of epithelial and lymphoid tissues of the palatine tonsils was studied in human embryos at the age of 8-34 weeks of development by means of histochemical, immunomorphological and morphometric methods. The anlage of the palatine tonsils appears at the age of 9 weeks of fetal development. At the age of 13-14 weeks of fetal development the tonsil suspension contains 2 subpopulations of lymphocytes possessing properties of T-cells differing in the ability of their superficial receptors to interact with sheep erythrocyte antigens forming rosettes (RFC--rosette forming cells) and with antigens of their own erithrocytes (autoRFC). The number both increases sharply by the 16th week of gestation. Simultaneously, essential alterations are noted in epithelial and lymphoid tissues. In epithelium of crypts cornified cells appear; the amount of lymphoid tissue increases sharply, primary follicles without reactive centers appear, lymphocytic infiltration of epithelium occurs. The amount of RFC does not change considerably, and the amount of autoRFC has a tendency towards some increase. From the data obtained, it is possible to suggest that human palatine tonsils already at embryonic period participate in functioning of immunogenic organs and in maintaining of immunologic homeostasis of the fetal organism.     

Tonsil-derived mesenchymal progenitor cells acquire a follicular dendritic cell phenotype under cytokine stimulation

Tonsils comprise part of the mucosal immune system and contain lymphocytes, macrophages, and follicular dendritic cells (FDCs). FDCs are located in the B cell area of the follicles of secondary lymphoid organs, such as the spleen, tonsils, or lymph nodes, and they trap and retain immune complexes on their surfaces to regulate B cell activation and maturation. Stromal cells from the palatine tonsils are often used for FDC in vitro studies, and it has been reported that human palatine tonsils may be a good source of multipotent mesenchymal cells. Therefore, we assessed whether tonsil-derived mesenchymal stromal cells could differentiate into a FDC-like phenotype. We discovered that stromal cells isolated from human tonsils not only had the potential to differentiate into various cell types of mesenchymal origin, but they also could differentiate into FDC-like cells under cytokine stimulation in vitro.     

A nektaspid arthropod from the Early Cambrian Sirius Passet fauna, with a description of retrodeformation based on functional morphology

ABSTRACT. The Sirius Passet fauna from the Lower Cambrian of North Greenland yields a diverse suite of poorly sclerotized arthropods. A new nektaspid from the fauna described here differs from typical naraoiids in having six thoracic segments and in being isopygous. Soft parts are poorly known, but posterior limbs are preserved in some specimens. Although specimens are invariably highly flattened, details of the axial articulation suggest that the animal could enrol. The widths of the articulating half rings can be used to reconstruct both the degree of rotation at each articulation during enrolment and the height at which each point along the half ring is above the fulcrum, and this in turn may be used to make a full three-dimensional reconstruction of the exoskeleton. This method of retrodeformation is in principle applicable to the reconstruction of other taxa, especially trilobites, found in shales.