Braincase anatomy of Almadasuchus figarii (Archosauria,Crocodylomorpha) and a review of the cranial pneumaticity in the origins of Crocodylomorpha

Almadasuchus figarii is a basal crocodylomorph recovered from the Upper Jurassic levels of the Cañadón Calcáreo Formation (Oxfordian–Tithonian) of Chubut, Argentina. This taxon is represented by cranial remains, which consist of partial snout and palatal remains; an excellently preserved posterior region of the skull; and isolated postcranial remains. The skull of the only specimen of the monotypic Almadasuchus was restudied using high-resolution computed micro tomography. Almadasuchus has an apomorphic condition in its skull shared with the closest relatives of crocodyliforms (i.e. hallopodids) where the quadrates are sutured to the laterosphenoids and the otoccipital contacts the quadrate posterolaterally, reorganizing the exit of several cranial nerves (e.g. vagus foramen) and the entry of blood vessels (e.g. internal carotids) on the occipital surface of the skull. The endocast is tubular, as previously reported in thalattosuchians, but has a marked posterior step, and a strongly projected floccular recess as in other basal crocodylomorphs. Internally, the skull of Almadasuchus is heavily pneumatized, where different air cavities invade the bones of the suspensorium and braincase, both on its dorsal or ventral parts. Almadasuchus has a large basioccipital recess, which is formed by cavities that excavate the basioccipital and the posterior surface of the basisphenoid, and unlike other crocodylomorphs is connected with the basisphenoid pneumatizations. Ventral to the otic capsule, a pneumatic cavity surrounded by the otoccipital and basisphenoid is identified as the rhomboidal recess. The quadrate of Almadasuchus is highly pneumatized, being completely hollow, and the dorsal pneumatizations of the braincase are formed by the mastoid and facial antra, and a laterosphenoid cavity (trigeminal diverticulum). To better understand the origins of pneumatic features in living crocodylomorphs we studied cranial pneumaticity in the basal members of Crocodylomorpha and found that: (a) prootic pneumaticity may be a synapomorphy for the whole clade; (b) basisphenoid pneumaticity (pre-, postcarotid and rostral recesses) is a derived feature among basal crocodylomorphs; (c) quadrate pneumatization is acquired later in the history of the group; and (d) the rhomboidal sinus is a shared derived trait of hallopodids and crocodyliforms. The marine thallatosuchians exhibit a reduction of the pneumaticity of the braincase and this reduction is evaluated considering the two phylogenetic positions proposed for the clade.     

A unique predator in a unique ecosystem: modelling the apex predator within a Late Cretaceous crocodyliform-dominated fauna from Brazil

Theropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesized to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allows us to characterize the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group with that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialized apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (~600 N), the predation strategies of baurusuchids likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod Allosaurus fragilis and the living crocodylian Alligator mississippiensis) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviors for these animals. The unique selective pressures in the arid to semi-arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa.     

Insight into the evolution of avian flight from a new clade of Early Cretaceous ornithurines from China and the morphology of Yixianornis grabaui

In studies of the evolution of avian flight there has been a singular preoccupation with unravelling its origin. By contrast, the complex changes in morphology that occurred between the earliest form of avian flapping flight and the emergence of the flight capabilities of extant birds remain comparatively little explored. Any such work has been limited by a comparative paucity of fossils illuminating bird evolution near the origin of the clade of extant (i.e. 'modern') birds (Aves). Here we recognize three species from the Early Cretaceous of China as comprising a new lineage of basal ornithurine birds. Ornithurae is a clade that includes, approximately, comparatively close relatives of crown clade Aves (extant birds) and that crown clade. The morphology of the best-preserved specimen from this newly recognized Asian diversity, the holotype specimen of Yixianornis grabaui Zhou and Zhang 2001, complete with finely preserved wing and tail feather impressions, is used to illustrate the new insights offered by recognition of this lineage. Hypotheses of avian morphological evolution and specifically proposed patterns of change in different avian locomotor modules after the origin of flight are impacted by recognition of the new lineage. The complete articulated holotype specimen of Yixianornis grabaui, from the Early Cretaceous Jiufotang Formation of Liaoning Province, in north-eastern China, arguably the best-preserved basal ornithurine specimen yet discovered, provides the earliest evidence consistent with the presence of extant avian tail feather fanning.     

The Circumorbital Bones of the Gekkota (Reptilia: Squamata)

The enormous variation of the orbit in lepidosaurs is better conceptualized in terms of composition and configuration. Broadly, the orbit varies from having totally closed rim to being open posteriorly. Two processes are responsible for changes in the components of the circumorbital series, element loss and fusion. The resulting contacts among elements are the main factors determining orbital configuration. Here, we present a revision of the gekkotan circumorbital bones in the general context of the Lepidosauria. From observations of a sample of 105 species of gekkotans prepared using different techniques, we describe the main changes in the orbit and corroborate the presence or absence of some of the ambiguous elements such as the lacrimal and the jugal. The supraorbital bones of squamates are reviewed and some problems of homology are evaluated using recent phylogenenetic hypothesis. Anat Rec, 2010. © 2009 Wiley‐Liss, Inc.     

The skull of the Miocene Spheniscus urbinai (Aves,Sphenisciformes): osteology,brain morphology,and the cranial pneumatic systems

Spheniscus urbinai represents one of four extinct Spheniscus species from the Cenozoic of southern South America, known from several poorly described diversely complete skulls and postcranial elements. Here, we present a review of the cranial osteology of all known specimens (collected in Argentina, Chile, and Peru), including a paleoneurological analysis using CT scans, and an exploration of its cranial pneumaticity compared to other extinct and living seabirds. Our results show that among Spheniscus species, S. urbinai exhibits slightly greater cranial pneumaticity than the living species. Additionally, we confirm previous findings which indicate that the marked reduction of cranial pneumaticity—which is characteristic of living penguins—occurred early during the Eocene (as observed in the Antarctic penguin MLP 12-I-20-1, but not in the coeval Anthropornis).     

Neuroanatomy and inner ear labyrinths of the narwhal,Monodon monoceros,and beluga,Delphinapterus leucas (Cetacea: Monodontidae)

Narwhals (Monodon monoceros) and belugas (Delphinapterus leucas) are the only extant members of the Monodontidae, and are charismatic Arctic‐endemic cetaceans that are at risk from global change. Investigating the anatomy and sensory apparatuses of these animals is essential to understanding their ecology and evolution, and informs efforts for their conservation. Here, we use X‐ray CT scans to compare aspects of the endocranial and inner ear labyrinth anatomy of extant monodontids and use the overall morphology to draw larger inferences about the relationship between morphology and ecology. We show that differences in the shape of the brain, vasculature, and neural canals of both species may relate to differences in diving and other behaviors. The cochleae are similar in morphology in the two species, signifying similar hearing ranges and a close evolutionary relationship. Lastly, we compare two different methods for calculating 90var – a calculation independent of body size that is increasingly being used as a proxy for habitat preference. We show that a ‘direct’ angular measurement method shows significant differences between Arctic and other habitat preferences, but angle measurements based on planes through the semicircular canals do not, emphasizing the need for more detailed study and standardization of this measurement. This work represents the first comparative internal anatomical study of the endocranium and inner ear labyrinths of this small clade of toothed whales.     

Diaphragmatic defects,limb deficiencies,and ossification defects of the skull: A distinctive malformation syndrome

We report on prenatal and postnatal findings in 4 consecutive fetuses with a pattern of severe congenital anomalies who were born to a healthy nonconsanguineous couple. The spectrum of malformations includes diaphragmatic defects, hypoplastic lungs, omphalocele, limb deficiencies, syndactyly of toes, and ossification defects of the skull. This specific spectrum of anomalies is not fully compatible with that of any established syndrome. No prenatal exposure to any possible teratogen was found. Family history is suggestive for autosomal recessive inheritance, even though germ-line mosaicism in one of the parents cannot completely be excluded. © 1996 Wiley-Liss, Inc.     

Familial lethal skeletal dysplasia with cloverleaf skull and multiple anomalies of brain,eye, face and heart: a new autosomal recessive multiple congenital anomalies syndrome

We report on a 'new' lethal familial short-limb bone dysplasia associated with multiple anomalies in three sibs born to Arabic-Muslim consanguineous healthy parents. Clinical abnormalities included short limbs and short hands, cloverleaf skull, frontal bossing, wide anterior fontanel, hypertelorism, bilateral microphthalmia, cataract, low-set ears, narrow chest, ambiguous genitalia, cardiac ventricular septal defect (VSD) and agenesis of the corpus callosum. Radiological abnormalities included cloverleaf skull, hypoplastic clavicles and scapulae, thin, wavy cupped ribs, flat vertebral bodies with coronal clefting and several unossified vertebral pedicles and hypo-ossification of the pubic bone. The main changes noted in the long bones consisted of short-bowed long bones with abnormal metaphyses and unossified epiphyses. Chondro-osseous morphology documented degenerating chondrocytes with disorganization of the hypertrophied cartilage and short disorganized columns of hypertrophied areas. An autosomal recessive mode of inheritance seems most likely.     

The original boneheads: histologic analysis of the pachyostotic skull roof in Permian burnetiamorphs (Therapsida: Biarmosuchia)

Thickened, pachyostotic skulls are best known in pachycephalosaur dinosaurs, but evolved convergently in Permian burnetiamorphs as well as in some other stem‐mammal groups and Triassic archosauromorphs. Until now, only pachycephalosaur domes have been histologically sampled to reveal patterns of bone tissue microstructure and growth. Using computed tomography and osteohistology, we serially thin‐sectioned one of the smallest burnetiamorph skull caps ever recovered (estimated skull length = 10 cm), as well as an individual nearly twice as large, and here report the first cranial histological data from this clade. We recognize four highly vascularized histological zones visible in coronal thin‐sections, only one of which shares morphological similarities with the tripartite zonation previously reported in pachycephalosaur domes. Zone A forms the endocranial region of the skull cap and records disorganized primary osteons in a fibrolamellar complex. Zone B preserves a border of compact, avascular layers of parallel‐fibered bone surrounding an interior of partially remodeled vascular canals. Interestingly, the outline of Zone B resembles the shape of an incipient skull roof. Zone C forms the thickest portion of the skull cap and is composed of fast‐growing woven bone with minimal osteonal development. The superficial Zone D has a matrix of predominantly woven bone with narrower primary vascular canals than in deeper regions of the skull caps. Unlike in pachycephalosaurs, where primary vascular porosity is thought to decrease through ontogeny, both burnetiamorph skull caps preserve a thick Zone C of highly vascularized tissue. Additionally, the remnants of sutures are visible as radial struts that taper superficially, leaving no trace on the surface of the skull. Even in the smallest individual, the sutures are closed ectocranially, which is unusual, given that some large, presumably adult pachycephalosaur domes preserve open sutural gaps. Although pachycephalosaur and burnetiamorph skull domes are superficially similar, histological analysis reveals differences in their vascularity and construction that imply multiple evolutionary pathways to form an elaborate pachyostotic dome.     

颅骨来源骨髓基质干细胞的分离培养方法

背景：从小鼠颅骨提取的一类骨髓基质干细胞称为PA6细胞,研究者发现当PA6细胞与其他干细胞共培养时可向神经细胞分化,此特性可被应用于神经损伤部位的修复。所以,PA6细胞越来越受到研究者的关注,但目前国内对类似骨髓基质干细胞PA6的提取方法鲜见报道。 目的：分离培养SD大鼠颅骨来源的骨髓基质干细胞,体外观察细胞形态并免疫荧光鉴定。 方法：无菌条件下,取新生的SD大鼠颅骨将其剪碎,用含体积分数为10%胎牛血清的DMEM培养液冲洗颅骨碎片,反复吹打制成单细胞悬液,将其置于培养瓶中培养,多次换液培养纯化细胞。取第2代生长均一的细胞,倒置显微镜下观察细胞形态,并用免疫荧光染色法进行细胞表面标记鉴定。 结果与结论：原代细胞培养24 h后,骨髓基质干细胞开始贴壁;3 d后细胞数量增多,形态呈不规则形、多角形、三角形和扁平形;细胞传代后,形态基本均一,细胞排列呈放射状和束状,贴壁能力较强,部分细胞呈聚集生长,增殖速度比原代有明显的加快。免疫荧光染色检测CD105、CD73、CD44、CD90表达呈阳性,CD45、CD34、CD14和HLA-DR表达呈阴性,证实了提取的细胞为骨髓基质干细胞。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

A review of the European Harpirhynchidae (Acari, Prostigmata) with the description of a new species

Records of the European Harpirhynchidae Dubinin, 1957 (Acari, Prostigmata) are summarized and briefly discussed. This family is represented in Europe by 23 species belonging to three subfamilies, Harpirhynchinae (18 species recorded), Harpypalpinae Fain, 1972 (4 species recorded), and Ophioptinae Southcott, 1956 (1 species recorded). A new species Harpirhynchus dusbabeki sp. nov. from the bearded tit Panurus biarmicus (L., 1758) (Passeriformes, Timaliidae) in Slovakia is described. This new species differs morphologically from the two similar congeneric species, H. nidulans Nitzsch, 1818 and H. galeridae Fain, Bochkov et Mironov, 1999, by having setae 3a and two setae on both genua I and II.