Light rings in Chinese pine (Pinus tabulaeformis) in semiarid areas of north China and their palaeo-climatological potential

Light rings in conifer trees are characterized by a light-coloured, narrow latewood band of thin-walled tracheids. Most reports on light rings have been for subarctic and subalpine regions, and little is known about their occurrence in semiarid areas. Dendrochronological methods were used to date the occurrence of light rings in Chinese pine (Pinus tabulaeformis) in the semiarid region of north China. The anatomical and chemical characteristics and the potential environmental controls of their formation were investigated. Light rings in Chinese pine were dated to the year of their formation. The wall thickness and lumen diameter of the wood cells of light rings and reference rings were distinctly different. However, the configuration of the light-ring latewood cell walls was normal, although they were thinner than average, and their lignification had been completed normally. The climate characteristics that result in light-ring formation appear to be ongoing severe drought from the previous autumn to July of the current year in conjunction with a warm summer, suggesting that light rings can be used as indicators for past drought events.     

Muscle architecture of the common chimpanzee (Pan troglodytes): perspectives for investigating chimpanzee behavior

Thorpe et al. (Am J Phys Anthropol 110:179–199, 1999) quantified chimpanzee (Pan troglodytes) muscle architecture and joint moment arms to determine whether they functionally compensated for structural differences between chimpanzees and humans. They observed enough distinction to conclude that musculoskeletal properties were not compensatory and suggested that chimpanzees and humans do not exhibit dynamically similar movements. These investigators based their assessment on unilateral limb musculatures from three male chimpanzees, of which they called one non-adult representative. Factors such as age, sex, and behavioral lateralization may be responsible for variation in chimpanzee muscle architecture, but this is presently unknown. While the full extent of variation in chimpanzee muscle architecture due to such factors cannot be evaluated with data presently available, the present study expands the chimpanzee dataset and provides a preliminary glimpse of the potential relevance of these factors. Thirty-seven forelimb and 36 hind limb muscles were assessed in two chimpanzee cadavers: one unilaterally (right limbs), and one bilaterally. Mass, fiber length, and physiological cross-sectional area (PCSA) are reported for individual muscles and muscle groups. The musculature of an adult female is more similar in architectural patterns to a young male chimpanzee than to humans, particularly when comparing muscle groups. Age- and sex-related intraspecific differences do not obscure chimpanzee-human interspecific differences. Side asymmetry in one chimpanzee, despite consistent forelimb directional asymmetry, also does not exceed the magnitude of chimpanzee-human differences. Left forelimb muscles, on average, usually had higher masses and longer fiber lengths than right, while right forelimb muscles, on average, usually had greater PCSAs than left. Most muscle groups from the left forelimb exhibited greater masses than right groups, but group asymmetry was significant only for the manual digital muscles. The hind limb exhibited less asymmetry than the forelimb in most comparisons. Examination of additional chimpanzees would clarify the full range of inter- and intra-individual variation.     

On the head morphology of Phyllium and the phylogenetic relationships of Phasmatodea (Insecta)

Friedemann K., Wipfler B., Bradler S. and Beutel R.G. 2011 . On the head morphology of Phyllium and the phylogenetic relationships of Phasmatodea (Insecta). —Acta Zoologica (Stockholm) 00 : 1–16. External and internal head structures of Phyllium siccifolium are described in detail. The findings are compared with conditions found in other phasmatodeans and members of other neopteran lineages. The compiled 125 characters were analysed cladistically. A clade Eukinolabia (Phasmatodea + Embioptera) was confirmed. Synapomorphies of these two taxa are the shift of the origin of M. tentorioparaglossalis to the hind margin of the prementum, the presence of M. tentorioscapalis medialis, and antennal muscles that originate exclusively on the anterior tentorial arms. Within Eukinolabia, the position of Timema remains somewhat ambiguous because of missing anatomical data. However, it was confirmed as sister group of Euphasmatodea in a monophyletic Phasmatodea. Apomorphic groundplan features of Euphasmatodea are salivary ducts with separate external openings, apically rounded glossae, the presence of the galealobulus, and the reduction of the antennifer. The monophyly of Neophasmatidae was confirmed. Autapomorphies are the loss of M. frontobuccalis posterior, the anteriorly or dorsally directed maxillary palps, and the reduction of the mandibular incisivi. The analysis of characters of the head yielded three new autapomorphies of Phylliinae, the presence of a protuberance on the attachment site of the dorsal tentorial arms, dorsoventrally flattened maxillary‐ and labial palps, and possibly the narrow and U‐shaped field of trichomes on the apical part of the galea.     

Ontogeny of the jaw apparatus and suspensorium of the Tetraodontiformes

Konstantinidis, P. and Johnson, G. David 2012. Ontogeny of the jaw apparatus and suspensorium of the Tetraodontiformes. —Acta Zoologica (Stockholm) 93 : 351–366. The jaw apparatus and suspensorium of adult Tetraodontiformes are well adapted to a durophagous feeding habit. Anatomical indicators are the short, stout jaws and a suspensorium in which the quadrate lies in the same vertical plane as the autopalatine. In contrast, the palatoquadrate of larval Tetraodontiformes generally resembles that of larval percomorphs – a more posteriorly positioned quadrate and a slender and long Meckelian cartilage. Among Tetraodontiformes, the Triacanthodidae retain a protrusible upper jaw and a versatile suspensorium. The jaws of the Balistoidei have greater mobility achieved by a reduced autopalatine that has lost its bony contact with the suspensorium. In contrast to the Balistoidei, the beak‐like jaws of the Tetraodontoidei lack individual teeth in the biting part of the jaws. The autopalatine is enlarged, which results in immobilization of the ethmopalatine articulation. The Ostraciidae are exceptional in having the distal part of the autopalatine reduced, while the proximal part remains attached to the suspensorium.     

黄缘闭壳龟消化系统、呼吸系统的解剖

黄缘闭壳龟消化管总长度为背甲长的3.5～4.2倍.食管和胃壁厚,扩展性强,内壁有数条纵行皱襞.小肠较长,约占消化管总长度的60.9%,无盲肠,肠内壁有大小不一的纵行皱襞.肝较大,为体重的4.8%左右.胰脏长条形,沿十二指肠分布.气管和支气管均由呈"O" 形完全闭合的软骨环和环间韧带所构成.气管较长,有45～55个软骨环;支气管较短,有30～40个软骨环.肺长囊形,蜂窝状,紧贴在背甲的内表面,从肩带一直延展到腰带.     

Endocranial anatomy and life habits of the Early Triassic archosauriform Proterosuchus fergusi

Proterosuchids are an important group of carnivorous basal archosauriforms characterized by a bizarre and enigmatic downturned premaxilla that overhangs the lower jaw. They are particularly significant because they radiated in the immediate aftermath of the Permian–Triassic mass extinction and represent one of the best known ‘disaster taxa’ following that event. While traditionally considered to be semi-aquatic, recent histological studies and geological data have suggested that it is more likely that they inhabited terrestrial environments. By using computed tomographic (CT) data, we virtually reconstruct the brain endocast and endosseous labyrinths of two adult specimens of Proterosuchus fergusi from the earliest Triassic of South Africa, in an attempt to understand its life habits within the context of basal archosauriform evolution. Endocasts reveal that the brain cavity is tubular in shape and the endosseous labyrinths are highly pyramidal. The angle of the lateral semicircular canal suggests that P. fergusi naturally held its head upwards ~17°, while the length of the cochlear duct suggests its auditory abilities were specialized towards low-frequency sounds. Furthermore, beam theory analysis suggests that the rostrum of P. fergusi is highly resistant to both bending and torsion when compared to modern crocodilians, although this resistance is neither enhanced nor reduced by the overhanging premaxilla. Comparative anatomical analyses suggest P. fergusi was probably a semi-aquatic, generalist apex predator capable of surviving the harsh environmental perturbations of the Early Triassic.     

Schweingruber’s cosmos of inspiration

Born 29^th February 1936 near Bern, Switzerland, Fritz Hans Schweingruber worked as a teacher until 1965, obtained a PhD in botany from the University of Basel in 1972 (where he also obtained a Professorship in 1976), and started his lifelong career at the Swiss Federal Research Institute WSL in Birmensdorf right afterwards. Fritz developed a dendrochronological network across much of the Northern Hemisphere, expanded wood (xylem) science beyond forests, implemented wood anatomical techniques into dendroecology and paleoclimatology, and enthusiastically trained thousands of students, of which hundreds remained actively involved in the still emerging field of tree-ring research. Though Fritz died 7^th January 2020 after an extraordinary academic career, his intellectual legacy will continue to inspire scholars around the world.