The vermiculate surface pattern in brow ridges of Australopithecines and other very ancient hominids

A convoluted surface pattern of fine ridges, pits, and grooves characterized the brow ridges of Australopithecines and other very ancient fossil hominids. This vermiculate configuration terminated rather abruptly just below the fronto-zygomatic suture in Australopithecines. It was resistant to oriented cracking from weathering or fractures, contrasting with the smooth but structurally oriented zygomatic bone adjacent to it. The pattern apparently developed as individuals matured. The vermiculate pattern seems to have been a feature of brow surface in hominids through much of their identifiable history, despite substantial changes in shape and size of the supraorbital region during human evolution. Limitations on the area of vermiculate surface in Australopithecines suggest that the pattern was associated in some yet undetermined manner with overlying soft tissues. This gives evidence on the cause and functional significance of the vermiculate pattern in Neandertal and modern crania. Problems of describing surfaces as “vermiculate” are raised by observation of elaborations of surface relief on two individuals.     

Evidence of fungal decay in petrified legume wood from the Neogene of the Bengal Basin,India

Silicified fossil legume woods of Cynometroxylon Chowdhury & Ghosh collected from the Neogene (late Miocene) sediments of the Bengal Basin, eastern India, exhibit fungal decay seldom found in the fossil record. The wood possesses numerous perforate areas on the surface that seem to be the result of extensive fungal activity. In transverse section, the decayed areas (pockets) appear irregular to ellipsoidal in outline; in longitudinal section these areas of disrupted tissue are somewhat spindle-shaped. Individual pockets are randomly scattered throughout the secondary xylem or are restricted to a narrow zone. The aforesaid patterns of decay in fossil wood show similarities with that of white rot decay commonly produced by higher fungi, specifically basidiomycetes and ascomycetes. The host fossil wood harbors abundant ramifying and septate fungal hyphae with knob like swellings similar to pseudoclamps in basidiomycetes, and three-celled conidia-like reproductive structures. This record expands our current knowledge of wood decaying fungi-host plant interaction in the Neogene tropical forests of Peninsular India.     

Silurian fungal remains: probable records of the Class Ascomycetes

Among the abundant plant microfossils obtained from the late Silurian Burgsvik Sandstone are spores and filaments whose morphology suggests a fungal origin. These include large multiseptate spores resembling conidia of present-day Fungi Imperfecti; ovate, reniform, rugulately ornamented unicellular spores; branched filaments with perforate septa; and filaments with flask-shaped appendages resembling phialides. We suggest that these microfossils represent the remains of the imperfect stages of terrestrial Ascomycetes, and provide evidence for an origin of this group at least contemporaneous with the earliest land plants. Larger, ovoid and cylindrical heterogeneous bodies composed of hyphal fragments resemble the fecal pellets of mycophagous microarthropods. The implications of these in terms of early terrestrial ecosystems are discussed.     

Small Celastraceae and Polygonaceae twigs from the Upper Cenozoic (Ituzaingó Formation) of the La Plata Basin,Argentina

Two new wood types from the Late Cenozoic of the Ituzaingó Formation, La Plata Basin, Northeast Argentina add to our knowledge of South American Cenozoic plants. The materials were preserved by siliceous cellular permineralization, and they were prepared for microscopic examination by surface polishing and in thin sections. The anatomy of these new species was described. The relationship and comparison with the nearest living relatives (NLRs) are discussed. Maytenoxylon perforatum Franco gen. and sp. nov. is described as the first fossil wood referable to Celastraceae from South America. This new fossil species is related to extant Maytenus Molina. The other fossil twig, Ruprechtioxylon breae Franco sp. nov., has features of the Polygonaceae family and particularly resembles the extant specie Ruprechtia laxiflora Meisn. The occurrence of these fossil woods in south-eastern South America suggests that a relatively warm and dry to seasonally dry climate prevailed over this region of Gondwana during the Upper Cenozoic. It also provides new evidence for the hypothesis of the more wide distribution of Seasonally Dry Tropical Forest (SDTF) during the Upper Cenozoic.     

Pliocene facies and fossil contents of Qaret El-Muluk formation at Wadi El-Natrun depression, Western Desert, Egypt

Summary A sequence of late Pliocene sediments (Qaret El-Muluk Formation) covers large areas within Wadi El-Natrun depression; at the western periphery of the Nile Delta. The exposed sequence is composed of friable sands. mudstones, shales and minor limestones with combined total thickness of approximately 50 m. The fossil content consists of fresh and brackish water elements; charophytes, ostracods, gastropods, oysters and benthonic foraminifera. Planktonic forams which suggest marine influence have been also recorded. Terrestrial and aquatic continental vertebrate fauna includes mammals, reptiles, fish and aves. Several subtypes of ichthyoliths have been discovered in this study. Both lithological and paleontological data testify to a depositional environment which belongs to a marginal region where fluvial and marine deposition meet in shallow brackish lagoons. The sediments display changes from channelled fluvial sands to deltaic interbedded sands and mudstones to lagoonal shales and limestones to lacustrine chara limestones. Vertical stacking of facies is indicative of a series of transgressive-regressive events. The transgression brought shallow lagoonal conditions to the area. The transgressions were incomplete due to high rate of fluvial input. The lagoon dried up intermittently and calcretes and red brown soils were formed. Each regression is indicated by river generated clastic influx. During periods of active fluvial input, fluvial sediments prograded lagoonward. The clastic material was probably a mixture of reworked detritus from older sediments. An admixture of first cycle material from the basement rocks of the Red Sea hills cannot be ruled out. The diversity of provenance argues for several channels of a large river which existed during the late Pliocene.     

白蚁化石的地理分布及其演变

在地球的地质变迁中,白蚁类群的祖先,因古地理、古气候和古生物以的影响,基地理分布逐渐由高纬度向低纬度、由于冷地区向湿热地区变动。在漫长的历史演变过程中,一些属种遭到灭绝;一些属新的古生态环境中,演化成新的类群;一些属篑是得以存留下来,且延续生存至今。     

辽宁西部晚中生代地层研究之进展及存在问题——辽宁西部晚中生代地层和鱼群研究之四

辽宁西部晚中生代地层的综合层序为:义县组、九佛堂组、沙海组/张老公屯组、阜新组和孙家湾组.中西部朝阳—喀左—建昌以及凌源—三十家子盆地的义县组大致相当于东部阜新—义县—锦州盆地的狭义义县组及其底部的北票尖山含化石沉积夹层;中西部的九佛堂组则可与东部的金刚山、吐呼鲁和九佛堂三个岩组相对比;张老公屯组火山岩在层序上大部分可能位于九佛堂组和阜新组之间.以北票鲟、中华弓鳍鱼和狼鳍鱼为代表的鱼类化石普遍见于中国北方热河群及其相当岩群的下部河湖相地层中,以粒鳞鱼、固阳鱼和副狼鳍鱼为代表的鱼类化石多见于上部的扇三角洲和湖沼相含煤地层中.热河群及相当岩群时代的确定以及陆相侏罗—白垩系界线的厘定受制于目前地层和生物化石的研究程度.从鱼群的面貌看,义县—九佛堂组、沙海—阜新组及相当地层的时代可能分别为晚侏罗世晚期—早白垩世早期和早白垩世中期.     

江汉平原47号钻孔中的化石硅藻及其在古环境分析上的意义

江汉平原47号钻孔,位于湖北省江汉平原的江陵县,在其上段的46.6-2.2m层位上,有丰富的化石硅藻,约有26属148种,其中绝大多数是现存的淡水种类,并以附生性、沿岸带和浅水性的种类为主。种类较多的属有:Navicula(28种)、Cymbella(23种)、Achnanthes(15种)、Gomphonema(14种)和Eunotia(13种)。主要种类有Gomphonema tropicale var. nonpunctatum、Cyclotella comta、Cocconeis placemula vat. lineata和Stephanodiscus dubius等。硅藻中的种数(种/层)和数量(个/每克干沉积物)经历了一个从无到有、由少到多再逐渐减少直至消失的过程。这反映了水体环境也相应地经历了一个漫长的变迁过程:河流(可能是长江古道)→边滩和河漫滩→泛滥平原的积水洼地(湖泊或沼泽)→水体变深加宽→水体消失。从不同沉积相中各种类型(适酸碱度不同)的硅藻比例(即硅藻种谱),可以推测当时水体的酸碱度的变化不大,在中性或中性偏碱的范围。由化石硅藻并结合孢粉的矿物分析,可以推测当时硅藻大量生长繁殖时期的水温较凉,气候可能偏冷。硅藻的数量与沉积物的平均粒度呈明显的相关性,硅藻的种数与沉积物的平均粒度也呈明显的相关性。     

化石分散角质层的分类和命名概述

本文扼要地报道了前人对化石分散角质层分类和命名的进展,其中详细地介绍了Roselt和Schneider两种分类法。作者根据实践,认为气孔的有无、气孔器的组合类型和垂周壁的形态,可作为建立化石分散角质层的大类、类和亚类等较高的分类单位。