甘肃省重要古植物化石产地区划及保护利用     

王军  李小强  张海峰  郭兵  任文秀  彭措  冯备战  王玉玺  胡振波 《地质论评》2021,67(3):578-592

古植物化石是地质历史时期各类植物实体或遗迹的残留。对古植物化石产地进行系统的调查和区划研究是开展古生物化石保护和利用工作的基础。在资料研究和实地调查的基础上,对甘肃省24处重要古植物化石产地进行了评价和区划研究。甘肃省古植物化石产地可划分为北山地区、祁连山——河西走廊地区、鄂尔多斯和秦岭地区4个古生物化石大区以及6个古植物化石产地集中区。根据古植物化石产地的科学价值和美学价值,具体从科学性、稀有性、完整性、保存程度、可保护性5个单因素分别对24处重要古植物化石产地进行了评价。在单因素评价基础上进行了综合鉴评,共鉴评出世界级化石产地1处,国家级化石产地7处,省级化石产地16处。根据产地自然区划、行政区划等要素划分了古植物化石产地集中保护区6个。根据保护区内古植物化石产地级别及重要程度,划分出特级保护区2个,重点保护区2个和一般保护区2个。提出对重要古植物化石产地实行化石标本保护加原产地保护的建议。  相似文献   

元古宙真核藻类演化及环境控制因素     

张凤廉  王华建  张水昌  邓胜徽  叶云涛  邓焱  王晓梅  吕丹  卢远征  吕怡潼 《地质学报》2021,95(5):1334-1355

宜居地球、地外生命探索以及资源勘查等的需求使真核生物的早期溯源和演化趋势研究成为国际热点.根据已发现实体化石、分子化石和分子钟证据,将元古宙真核藻类演化划分为环境准备(2.45～1.70 Ga)、缓慢发展(1.70～0.80 Ga)、剧烈波动(0.80～0.64 Ga)、快速辐射(0.64～0.54 Ga)四个阶段.元古宙真核生物的出现、演化和辐射进程与地球氧化和极端气候事件(如冰期)的发生具耦合性,表现出早期生命与地球表层环境的协同演化.真核藻类在1.70～0.80 Ga期间的缓慢演化可能与长期较低的大气氧含量(约为现今水平的1％～10％PAL)有关.低的大气-海洋氧化程度不仅限制了真核藻类生存空间,也通过对氮、磷等营养元素的供应约束,限制了真核藻类初级生产力水平.因此,地球表层氧化可能是地球宜居演化,并孕育出真核生物等各种复杂生命的主要原因.从地球系统形成与演变的角度探索生物圈演化或能对生命的过去和未来给出更为可靠的答案.  相似文献   

人类从哪里来？——（4）人类演化与古地理、古环境和古气候变化     

季强  季燕南  吴文盛 《江苏地质》2021,45(1):1-7

详细介绍了8 Ma以来全球气候变化的规律,研究表明地球上主要发生过3次冷气候事件：第一次冷气候事件大约发生在距今7 Ma,一股强烈的干冷气流刮过欧洲大陆,穿越赤道地区直达非洲大陆,使得原始森林开始萎缩,面积的缩小导致古猿与人类发生演化分异;第二次冷气候事件大约发生在距今4.2 Ma,那时干冷气候持续发展,非洲大陆的原始森林进一步萎缩,并逐渐演化为稀树草原,出现了南方猿人和傍人;第三次冷气候事件大约发生在距今2.3 Ma,全球气候变化波动较大,冷-暖气候交替发育,地球上出现了真正意义上的人（人属）,并逐渐演化成现代人。根据目前的研究,人类的起源和演化与古地理、古环境和古气候变化密切相关,人类演化历史大致可分为7个时期：撒海尔猿人—原初猿人时期、地居猿人时期、南方猿人—傍人时期、能人—鲁道夫人时期、匠人—直立人时期、先驱人—海德堡人时期和智人时期。  相似文献   

The molecular composition of ambers     

J.O. Grimalt  B.R.T. Simoneit  P.G. Hatcher  A. Nissenbaum 《Organic Geochemistry》1988,13(4-6)

Bulk (elemental composition, IR, CP/MAS ¹³C NMR) and molecular (GC-MS) analyses have been performed on a series of ambers and resins derived from different locations (Dominican Republic, Philippines, Canada, Israel, New Zealand, Chile) having diverse botanical affinities (Araucariaceae, Hymenaea) and variable age (from Holocene to Early Cretaceous). No major differences have been observed from the elemental composition and the spectroscopic data; however, the molecular analyses of the solvent extractable fraction show that a specific mixture of components is present in each sample. These are mainly diterpenoid products that in general are also found abundantly in the higher plants from which the ambers and resins originate. Nevertheless, a direct relationship between major terpenoid constituents in fossil resins and precursor plant materials can only be established for the younger samples.Irrespective of the geographical or botanical origin of the ambers and resins, several common age-dependent molecular transformation trends can be recognized: (1) progressive loss of olefinic bonds (especially those located in exocyclic positions), (2) decrease of functionalized products, and (3) increasing proportion of aromatized components. However, even in the samples of older age (Cretaceous) the degree of aromatization is very low when compared with that of other higher-plant related materials such as fossilized woods or low rank coals. This indicates that maturation must involve essentially olefin polymerization processes instead of extensive aromatization.  相似文献   

江西弋阳港口盆地林山组地层时代讨论     

李浩昌  曹双林  梁发辉 《华东地质学院学报》1989,(2)

本文讨论了江西弋阳港口盆地林山组中的植物化石群。根据其组份特征,可确定该地林山组时代为早侏罗世中晚期,可与鄂西香溪组中下部的植物群对比。  相似文献   

Palaeozoic and early Mesozoic fish faunas of the Japanese Islands   总被引：2，自引：0，他引：2  

MASATOSHI GOTO 《Island Arc》1994,3(4):247-254

Abstract In recent years, many fish teeth and scales have been found from the Palaeozoic and Mesozoic age strata of the Japanese Islands. This study is a compilation of the Japanese fish record from the Palaeozoic and early Mesozoic age deposits. Based on the published and unpublished data, the fossil fishes from the Palaeozoic and Early Mesozoic of Japan can be classified into 27 genera and 33 species, that is, one species of Devonian placoderms, 19 species of Permian to Jurassic elasmobranchs, three species of Permian cochliodonts, seven species of Carboniferous to Permian petalodonts, and three species of Triassic to Jurassic osteichthyans.  相似文献   

A primitive odobenine walrus of Early Pliocene age from Japan     

Hideo  Horikawa 《Island Arc》1994,3(4):309-328

Abstract The well preserved cranium of Protodobenus japonicus, a new genus and species of odobenine walrus, is from the lower part of the Tamugigawa Formation at Ooshima-mura, Higashi Kubiki-gun, Niigata Prefecture, central Japan. The lower part of the formation that yielded P. japonicus is Early Pliocene, dating approximately from 5.0 to 4.9 Ma. The skull of P. japonicus is generally shaped like that of the modern walrus, Odobenus rosmarus (Linnaeus, 1758), but is much more primitive, especially in the dentition. Protodobenus japonicus is derived from the Imagotariinae. It is similar to such primitive fossil walruses as Prorosmarus alleni from the Western Atlantic and Aivukus cedrosensis from Baja California, and has some similarities as well as significant differences from them. Protodobenus japonicus could have evolved directly into Odobenus in the North Pacific Ocean, and could have dispersed directly to the Arctic Ocean. This is contrary to the scenario proposed by Repenning and Tedford, in which primitive odobenids, like Aivukus cedrosensis, migrated to the Atlantic Ocean through the Central American Seaway and returned to the North Pacific Ocean as O rosmarus via the Arctic about 0.6 Ma. Regarding the first lower premolar of the living walrus, Fay concluded after studying fetal O. rosmarus that the first premolar (P₁) of the mandible is absent, and that the lower tooth row consists of: C₁ P₂, P₃, P₄. Protodobenus japonicus has in its mandible I _1-2 C₁ P₂, P₃, P₄, and this is the primitive pinniped formula. Pinnipeds typically lose the molars, not the anterior premolars, and the present author believes that the correct tooth formula for O rosmarus is C₁ P₁, P₂, P₃. Its skull, palate, and mandible suggest that P. japonicus had morphology pre-adapted to an early stage of benthic suction feeding, but it probably was unable to rely on that method of feeding. The discovery of P. japonicus demonstrates that the odobenine lineage (true walruses) goes back in time at least 5 Ma. Other more aberrant odobenine walruses, such as Aivukus and Prorosmarus, and pseudo-walruses of the subfamily Dusignathinae, are more distantly removed from the lineage leading to living walruses than has previously been suspected.  相似文献   

Miocene pinnipeds of the otariid subfamily Allodesminae in the North Pacific Ocean: Systematics and relationships   总被引：1，自引：0，他引：1  

Lawrence G.  Barnes Kiyoharu  Hirota 《Island Arc》1994,3(4):329-360

Abstract Fossil pinnipeds in the extinct otariid subfamily Allodesminae are large, relatively highly evolved marine carnivores that became abundant and diverse in Middle Miocene time and were restricted to the North Pacific Ocean. Their record extends from early Middle Miocene through Late Miocene, with records from California, Oregon, Washington, Baja California and Japan. Allodesmines are characterized by extreme sexual dimorphism, a large orbit, retracted orbital margin of the zygomatic arch, a deeply mortised jugal-squamosal junction, wide palate, bulbous cheek tooth crowns, nearly flat tympanic bulla with wrinkled ventral surface, a large tympanohyal fossa, large ear ossicles and deep mandible. Eleven allodesmine species are known (eight of which are named), in at least four genera, and most belong to the typical genus Allodesmus Kellogg, 1922. The earliest and most generalized allodesmine known is from the early Middle Miocene (ca 16 Ma) Astoria Formation in coastal Oregon. The last known records are from Late Miocene rocks (ca 10 Ma) in California and Washington. New taxa proposed here are: the genus Brachyallodesmus Barnes and Hirota, to contain Allodesmus packardi Barnes, 1972; the genus Megagomphos Hirota and Barnes, to contain Allodesmus sinanoensis (Nagao, 1941); the species Allodesmus sadoensis Hirota, (Middle Miocene, Japan); the species Allodesmus megallos Hirota (Middle Miocene, Japan); and the species Allodesmus gracilis Barnes (Middle Miocene, California). Additionally, the genus Atopotarus Downs, 1956, and the species Allodesmus kelloggi Mitchell, 1966, are resurrected. Allodesmines were apparently a rapidly evolving group, and most appear to have been adapted to roles later filled by otariine, dusignathine and imagotariine otariids, and the Phocidae (true seals). They became extinct in Late Miocene time and left no living descendants. Although some of their characters evolved convergently with various living species of the pinniped family Phocidae, Allodesminae are an otariid group and not part of the evolutionary history of Phocidae.  相似文献   

Summary of the fossil record of pinnipeds of Japan, and comparisons with that from the eastern North Pacific     

Shigeo  Miyazah Hideo  Horkawa Naoki  Kohno Kiyoharu  Hirota Masaichi  Kimura Yoshkazu  Hasegawa Yukimitsu  Tomida Lawrence G.  Barnes Clayton E.  Ray 《Island Arc》1994,3(4):361-372

Abstract The fossil pinniped record of the North Pacific Ocean includes both Phocidae and Otariidae ( sensu lato ), extends from the Late Oligocene to the Late Pleistocene, is taxonomically diverse, and is constantly becoming more complete owing to additional important discoveries. The earliest and most diverse fossil pinnipeds in the North Pacific are otariids, the phocids not appearing until the latest Pliocene. The theoretical center of otariid pinniped evolutionary history has been considered by some to be in the eastern North Pacific. New materials from the western North Pacific, however, including representatives of the subfamilies Enaliarctinae, Imagotariinae, Odobeninae and Otariinae, indicate that pinniped evolutionary patterns were basin-wide phenomena, and that a more complete record undoubtedly would reveal numerous trans-Pacific distributions. This would be expected considering the distributions of living species. The paucity of fossil Phocidae and their absence from pre-Pliocene deposits are consistent with theories that the family primarily evolved outside the North Pacific.  相似文献   

General aspects of the evolutionary history of whales and dolphins     

R. Ewan  Fordyce Lawrence G.  Barnes Nobuyuki  Miyazah 《Island Arc》1994,3(4):373-391

Abstract The Cetacea are the most diverse and highly aquatically adapted group of mammals. Their fossil record extends back at least to the Middle Eocene ( ca 50 Ma), and they will possibly be found earlier, judging by the relatively highly evolved nature of the earliest known whales. The most likely terrestrial ancestors of whales are the mesonychids, primitive hoofed mammals with omnivorous diets. Recently discovered archaeocetes with large, mesonychid-like heads and dentitions and functional hind limbs reconfirm earlier ideas about the mesonychid origin of cetaceans and the amphibious nature of the earliest transitional forms. Fossil cetaceans are relatively abundant and diverse thoughout the world, and are now known from every continent, including Antarctica. Odontocetes evolved echolocation to locate food. Mysticetes developed bulk feeding adaptations. Both undoubtedly evolved from archaeocetes, and the monophyly of Cetacea is the most parsimonious present hypothesis. Chromosomal and molecular evidence has taken an increasingly important role in determining cetacean relationships, but fossils and classical comparative morphological studies remain a necessary and pivotal source of information about cetacean phylogeny.  相似文献