Fossil ovipositions of dragonflies: Review and interpretation

The paper deals with the stratigraphic range and morphology of fossil formations on plants interpreted as insect ovipositions. Our analysis of the insect fossil record has shown that the endophytic ovipositions probably belong to the Kennedyina and Triadophlebiina (in the Paleozoic and Lower Mesozoic) and to the Calopterygina (in the Upper Mesozoic and Cenozoic).     

A review of the chronostratigraphical ages of Middle Triassic to Late Jurassic dinoflagellate cyst biozones of the North West Shelf of Australia

The chronostratigraphical ages of the 20 dinoflagellate cyst zones and one dinoflagellate cyst assemblage for the Middle Triassic (Ladinian) to the Jurassic-Cretaceous transition of the North West Shelf of Australia are comprehensively reviewed. Evidence from macro- and micropalaeontology, palynology and strontium isotopes made available after the establishment of these biozones in the 1980s has been used to reassess the ages of this important zonal scheme and to calibrate it to the international stratigraphical stages. The Shublikodinium Superzone is renamed herein as the Rhaetogonyaulax Superzone, and based on conodont evidence is determined to span the Ladinian to Early Sinemurian. This is significantly shorter in duration than was originally envisaged (Late Anisian to Late Pliensbachian). The Luehndea Assemblage is a low diversity dinoflagellate cyst association which marks a eustatic rise; it is subdivided into two subzones. It is of latest Pliensbachian to Early Toarcian age, based largely on palynological evidence. The Bajocian to earliest Oxfordian Pareodinia ceratophora Superzone represents the inception of a continuous Mesozoic-Cenozoic dinoflagellate cyst record in Australia. It comprises seven zones, which are considered to be slightly older than originally interpreted. The overlying Pyxidiella Superzone is characterised by diverse dinoflagellate cyst associations. It is Early Oxfordian to Kimmeridgian in age, and comprises three zones. The bases of the Wanaea spectabilis and Wanaea clathrata zones are reinterpreted as being slightly older than originally proposed. The superjacent Fromea cylindrica Superzone is Tithonian to earliest Valanginian and modified ages are indicated for four of the nine zones. This unit is dominated by endemic dinoflagellate cysts, reflecting a global trend towards provincialism at this time due to a regressive eustatic regime.     

中国中,新生代大植物化石新属索引：（1865—1990）

系统地检索1865-1990年的古植物文献,搜录了根据中国材料建立的中、新生代化石属113个,分属于蕨类植物门和种子植物门等.     

The phylogeny of the 'higher' temnospondyls (Vertebrata: Choanata) and its implications for the monophyly and origins of the Stereospondyli

A parsimony analysis of 'higher' temnospondyls (all temnospondyls descended from the common ancestor of Eryops and Parotosuchus ) was performed using 37 terminal taxa and 121 osteological characters. Bremer support values for each internal node were calculated as a measure of clade strength. Additionally, the shortest trees that conformed to some alternative hypotheses were searched for. The following new taxa are established on the basis of the results: Euskelia (the clade containing the Eryopoidea and Dissorophoidea), Limnarchia (the clade containing Trimerorhachidae, Dvinosauroidea, Archegosauroidea and Stereospondyli), Dvinosauria (the clade containing Trimerorhachidae and Dvinosauroidea), Stereo-spondylomorpha (the clade containing Archegosauroidea and Stereospondyli), Capitosauria (the clade containing Lydekkerina and 'capitosauroids'), and Trematosauria (the clade containing Trematosauroidea, Rhytidosteidae, Plagiosauroidea, Metoposauroidea and Brachyopoidea). The monophyly of the assemblage of Mesozoic families called the Stereospondyli by Romer is supported. The dominance of the Stereospondyli in the Mesozoic and its rarity in the Palaeozoic is discussed. It is suggested that the radiation of the diverse stereospondyl clades, the Capitosauria and Trematosauria, began in the Late Permian of Gondwana, in a 'safe haven' that was less severely affected by the Late Permian extinction event. It is further speculated that the 'safe haven' was located in Antarctica, or possibly Australia.     

中国中生代晚期及第三纪鱼类区系中的若干分布格局问题

日本列岛和中国大陆东部的现生淡水鱼类区系存在显著的差异,但这两地上新世和中新世的鱼类区系已发现的组成成分却似乎比现代鱼类区系要接近得多。而在中国东部渤海沿岸发现的早第三纪或始新世的鱼类区系成分则显示出与北美西岸同时代鱼类区系的惊人相似,展现出一个“跨太平洋格局”。中国中生代晚期或早白垩世的鱼类区系从组成和分布上可以划分为两个组合。分布于北部的一个组合中土著类型较多,分布于东南部的组合表现出一些与南美东北部及非洲西部鱼类区系的相似性,这种分布格局涉及到南、北两半球的大陆。 本文对上述分布格局作一简单介绍,并作初步解释： １）早白垩世的副鲚鱼亚科鱼类在西非、南美洲东北部的分布曾被解释为１）历史上曾存在过一个包括副鲚鱼亚科在内的广布单系类群;２）中国东南部早白垩世鱼类区系起源于冈瓦纳;３）中国东南部早白垩世鱼类区系中至少有某些种类是近岸鱼类。本文倾向于接受后两种建议。 ２）始新世渤海沿岸及北美绿河页岩鱼类区系的“跨太平洋”分布格局曾有人用“太平洋洲假说”来说明。本文作者不赞成这种解释,认为这一分布格局的形成有多种原因,如当时宽阔的白令陆桥及露出海面的北极地区可作为两地鱼类的通道;两地的近岸鱼类可沿当时连续的海岸来往,     

青藏高原隆升的气候环境效应与脊椎动物演化模式*

在青藏高原逐渐形成的过程中, 本地区的现代生物多样性塑造受到其巨大的影响, 与此同时, 许多起源于高原的物种甚至现代广布类群祖先的洲际扩散也由其驱动。在中生代时期, 青藏高原今天所处的地区覆盖着广阔的海洋, 喜马拉雅山脉的三叠纪海相沉积中产有鱼龙和旋齿鲨等脊椎动物化石。至侏罗—白垩纪, 西藏东南部的部分地区逐渐脱离海洋环境, 在昌都盆地形成了与当时四川盆地相似的淡水湖泊, 恐龙等爬行动物则在湖边活动。新生代早期印度板块与欧亚板块的碰撞使青藏高原逐渐隆起, 一些热带、亚热带鱼类的发现, 表明当时青藏地区内部与东南亚的热带地区之间可能有水系连通。随着这一地区地势隆起幅度显著升高, 环境变干、变凉, 致使喜暖鱼类终于在此绝迹, 并转换为青藏高原特有的裂腹鱼类。青藏高原的快速上升导致季风气候加强, 中亚内陆地区的气候持续走向干旱, 中国西部的中新世动物群主要由耐旱的草原型哺乳动物组成, 还有耐旱的鸟类和爬行动物共生。青藏高原在上新世最终达到现代的高度, 其气候环境已具有冰冻圈的特点, 成为冰期动物群最初的演化中心。2.6 Ma全球气温第一次下降到低于今天的水平, 已经适应了冰冻环境的动物迅速扩散到青藏高原周边以及更遥远的地区, 成为现代动物多样性的基础。青藏高原在地质历史时期经历了复杂而大规模的环境变化, 这一系列的地质运动和地貌演化引发并形成了青藏高原及周边地区气候格局, 促进了本地区生物多样性的发展。     

中国中、新生代大植物化石新属记录(1991-2000)

记录1991—2000年间根据中国中、新生代大植物化石建立的新属41个(新生代的2个,中生代的39个);详细记录每个属的特征、模式种、地理分布及地质时代;对模式种的创建者、创建年代、所在文献的页码、图版、产地层位、标本保存状态、分类位置以及保存单位等也作详细介绍;另有一属模式种的模式标本并非产自中国,但该属同时也包含着部分中国的标本,则在附录中作介绍。     

Bioeroders in fossil reefs

Summary Boring algae, fungi and bacteria have been the most constant factor in bioerosion through earth history. Their record reaches back into the middle Precambrian. The only fossil reefs specifically researched for these microendoliths are of Triassic and Upper Jurassic age. Boring worms appear in reefs in the Lower Cambrian. Boring sponges and bivalves first appear also in the lower Paleozoic, but do not become abundant in reefs until the Triassic. Effective substrate excavating grazers are relatively young geologically: Patellids and substrate excavating Echinoids evolved in the Triassic but did not become important bioeroders until the Jurassic or Cretaceous. Scarid fishes are even younger, the oldest representatives having been found in the Miocene. Thus, it seems that the intensity of bioerosion changed significantly during earth history. This may have had consequences for diversity of reef organisms, quality and quantity of reef debris, for diagenesis and record of reef rock.     

The Gondwanan and South American Episodes: Two Major and Unrelated Moments in the History of the South American Mammals

The first steps in the history of South American mammals took place ca. 130 Ma., when the South American plate, still connected to the Antarctic Peninsula, began to drift away from the African-Indian plate. Most of the Mesozoic history of South American mammals is still unknown, and we only have a few enigmatic taxa (i.e., a Jurassic Australosphenida and an Early Cretaceous Prototribosphenida) that pose more evolutionary and biogeographic questions than answers. The best-known Mesozoic, South American land-mammal fossils are from Late Cretaceous Patagonian beds. These fossils represent the last survivors of non- and pre-tribosphenic Pangaean lineages, all of them with varying endemic features: some with few advanced features (e.g., ?Eutriconodonta and “Symmetrodonta”), some very diversified as endemic groups (e.g., ?Docodonta Reigitheriidae), and others representing vicariant types of well known Laurasian Mesozoic lineages (e.g., Gondwanatheria as vicariant of Multituberculata). These endemic mammals lived as relicts (although advanced) of pangeic lineages when a primordial South American continent was still connected to the Antarctic Peninsula and, at the northern extreme, near the North American Plate. By the beginning of the Late Cretaceous, the volcanic and diastrophic processes that finally led to the differentiation of the Caribbean region and Central America built up transient geographic connections that permitted the initiation of an overland inter-American exchange that included, for example, dinosaurian titanosaurs from South America and hadrosaurs from North America. The immigration of other vertebrates followed the same route, for example, polydolopimorphian marsupials. These marsupials were assumed to have differentiated in South America prior to new discoveries from the North American Late Cretaceous. The complete extinction of endemic South American Mesozoic mammals by the Late Cretaceous-Early Paleocene, and the subsequent and in part coetaneous immigration of North American therians, respectively, represent two major moments in the history of South American mammals: a Gondwanan Episode and a South American Episode. The Gondwanan Episode was characterized by non- and pre-tribosphenic mammal lineages that descended from the Pangeic South American stage (but already with a pronounced Gondwanan accent, and wholly extinguished during the Late Cretaceous-Early Paleocene span). The South American Episode, in turn, was characterized only by therian mammals, mostly emigrated from the North American continent and already with a South American accent obtained through isolation. The southernmost extreme of South America (Patagonia) remained connected to the present Antarctic Peninsula at least up until about 30 Ma., and both provided the substratum where the primordial cladogenesis of “South American” mammals occurred. The resulting cladogenesis of South American therian mammals followed Gould's motto: early experimentation, later standardization. That is to say, early cladogenesis engendered a great variety of taxa with scarce morphological differentiation. After this early cladogenesis (Late Eocene-Early Oligocene), the variety of taxa became reduced, but each lineage became clearly recognizable distinctive by a constant morphologic pattern. At the same time, those mammals that underwent the “early experimentation” were part of communities dominated by archaic lineages (e.g., brachydont types among the native “ungulates”), whereas the subsequent communities were dominated by mammals of markedly “modern” stamp (e.g., protohypsodont types among the native “ungulates”). The Gondwanan and South American Episodes were separated by a critical latest Cretaceous-earliest Paleocene hiatus, it is as unknown as it is important in which South American land-mammal communities must have experienced extinction of the Gondwanan mammals and the arrival and radiation of the North American marsupials and placentals (with the probable exception of the xenarthrans, whose biogeographic origin is still unclear).     

Ostracod recovery in the aftermath of the Permian–Triassic crisis: Palaeozoic–Mesozoic turnover

Results of a detailed bathymetric survey of Crater Lake conducted in 2000, combined with previous results of submersible and dredge sampling, form the basis for a geologic map of the lake floor and a model for the filling of Crater Lake with water. The most prominent landforms beneath the surface of Crater Lake are andesite volcanoes that were active as the lake was filling with water, following caldera collapse during the climactic eruption of Mount Mazama 7700 cal. yr B.P. The Wizard Island volcano is the largest and probably was active longest, ceasing eruptions when the lake was 80 m lower than present. East of Wizard Island is the central platform volcano and related lava flow fields on the caldera floor. Merriam Cone is a symmetrical andesitic volcano that apparently was constructed subaqueously during the same period as the Wizard Island and central platform volcanoes. The youngest postcaldera volcanic feature is a small rhyodacite dome on the east flank of the Wizard Island edifice that dates from 4800 cal. yr B.P. The bathymetry also yields information on bedrock outcrops and talus/debris slopes of the caldera walls. Gravity flows transport sediment from wall sources to the deep basins of the lake. Several debris-avalanche deposits, containing blocks up to 280 m long, are present on the caldera floor and occur below major embayments in the caldera walls. Geothermal phenomena on the lake floor are bacterial mats, pools of solute-rich warm water, and fossil subaqueous hot spring deposits. Lake level is maintained by a balance between precipitation and inflow versus evaporation and leakage. High-resolution bathymetry reveals a series of up to nine drowned beaches in the upper 30 m of the lake that we propose reflect stillstands subsequent to filling of Crater Lake. A prominent wave-cut platform between 4 m depth and present lake level that commonly is up to 40 m wide suggests that the surface of Crater Lake has been at this elevation for a very long time. Lake level apparently is limited by leakage through a permeable layer in the northeast caldera wall. The deepest drowned beach approximately corresponds to the base of the permeable layer. Among a group of lake filling models, our preferred one is constrained by the drowned beaches, the permeable layer in the caldera wall, and paleoclimatic data. We used a precipitation rate 70% of modern as a limiting case. Satisfactory models require leakage to be proportional to elevation and the best fit model has a linear combination of 45% leakage proportional to elevation and 55% of leakage proportional to elevation above the base of the permeable layer. At modern precipitation rates, the lake would have taken 420 yr to fill, or a maximum of 740 yr if precipitation was 70% of the modern value. The filling model provides a chronology for prehistoric passage zones on postcaldera volcanoes that ceased erupting before the lake was filled.     

L'origine et l'évolution du xylème chez les Trachéophytes

Abstract

Xylem origin and evolution in the Tracheophyta. - The research on the xylem origin and evolution leads to investigate three features - guides:

—Passage from homoxyly to heteroxyly.

—Reduction of the importance of primary centripetal xylem in geological time.

—Progressive decrease of initial cambial cells lenght in the main groups of plants.

In this connection, one should recall the phloem-xylem evolution laws instituted by Chauveaud (1931).

From this well defined estimations on fossil vascular plants with secondary xylem, a clear evaluation of phylogenic significance of wood pattern by means of correlation with a wide range of various anatomical features is reached.

Salient evolutionnary trends of secondary xylem are illustrated with significative pattern examples related more particulary to fossil homoxylous structures of Sphenophyta, Gymnosperms and homoxylous or heteroxylous Dicotyledons.

Furthermore, unusual and rare structure of Pentoxylales and Rhexoxylales, particularly with regard to the cambium functionning must be recalled.     

Survival patterns of macrobenthic marine assemblages during the end-Permian mass extinction in the western Tethys (Dolomites, Italy)

The ecological competition between brachiopods and bivalves is analysed by means of a quantitative palaeoecologic method applied on four assemblages located within a short stratigraphic interval, approximately 2 m thick, in the lower Tesero Member of the Werfen Formation (in the Southern Alps). The assemblages originate from the Tesero, Bulla and Sass de Putia sections. The analysed stratigraphic interval, uppermost Changhsingian in age, is located between the early and heaviest phase of the end-Permian mass extinction, which occurred across the Bellerophon/Werfen formational boundary (Event Boundary), and the Permian/Triassic boundary (Chronological Boundary), when nearly all the Permian stenotopic holdovers disappeared.These assemblages are characterised by small sized skeletons (“Lilliput effect”), which represent an adaptive survival strategy in stressed and harsh habitats resulting from the climatic and palaeoceanographic changes connected with the mass extinction. The Tesero assemblages are dominated by rhynchonelliform brachiopod Orbicoelia (bed CNT10) or Streptorhynchus (bed CNT11A), which were mostly attached at the top of shallow microbialitic mounds. These assemblages are again dominated by Permian stenotopic taxa and show a Palaeozoic structure. The Tesero habitat, which again permitted the survival of brachiopods, represented one of the last refuges in the western Tethys. On the contrary, the Bulla (BU9-10) and Sass de Putia (wPK13A) assemblages are bivalve-dominated, and thus show an ecologic structure typical of Early Triassic post-extinction marine benthic communities or Palaeozoic stressed marine communities. The bivalve-dominated assemblages proliferated in prevailing muddy siliciclastic substrates, with brief episodes of microbial algal growth. The most important environmental limiting factors and leading causes of end-Permian mass extinction are discussed in terms of palaeoautecologic and palaeosynecologic analysis.The different taxonomic composition and ecologic structure of the assemblages is related to palaeogeography, including water depth and connections with the open sea. The brachiopod-dominated assemblage, exclusive of the Tesero section, proliferated in microbial carbonate habitats in near-shore environments. The bivalve-dominated assemblages, which were more widespread than the brachiopod assemblages in the Dolomites and also occurred in other western Tethys localities, occur in more open and deeper marine environments. In the western Tethys margins, the local distribution of mixed faunas suggests that the extinction of Permian stenotopic taxa was caused by the onset of poisonous water on the shelves originating from deep marine environments.This extinction pattern appears to be a regional phenomenon and does not seem be applicable on a global scale. The extinction events were controlled by a complex network of interactive factors and the survival of faunal elements was probably stochastic.