松属的起源、演化及扩散

在松属的系统演化、化石历史和现代分布研究的基础上,讨论了松属的起源、演化和扩散问题.松属的现代分布中心在北美洲,但原始类群主要集中在中国西南-越南一带,康滇古陆晚三叠纪地层发现了最早的松属孢粉化石,因而这一地区是松属的起源地,起源时间为三叠纪.起源后向西通过地中海区到达欧洲、北美,向东北穿过白令陆桥到达北美,向南到达印度尼西亚,向北到达西伯利亚和北极地区.     

Allometric Scaling in the Earliest Archaeopteryx lithographica

Archaeopteryx is almost universally considered a primitive bird. Debate persists, however, about the taxonomic assignment of the six skeletal fossils. Allometric scaling of osteological data shows that all specimens are consistent with a single growth series. The absence of certain bone fusions suggests that no specimen is full-grown. Allometric patterns, as compared to growth gradients of other dinosaurs, extant ectotherms, and extant endotherms, suggest that Archaeopteryx was likely a homeothermic endotherm with rapid growth and precocial abilities for running and flying. Multivariate allometric models offer a significant potential for interpreting ontogenetic patterns and phylogenetic trends in the fossil record.     

The impact of the pull of the recent on the history of marine diversity

Up to 50% of the increase in marine animal biodiversity through the Cenozoic at the genus level has been attributed to a sampling bias termed "the Pull of the Recent," the extension of stratigraphic ranges of fossil taxa by the relatively complete sampling of the Recent biota. However, 906 of 958 living genera and subgenera of bivalve mollusks having a fossil record occur in the Pliocene or Pleistocene. The Pull of the Recent thus accounts for only 5% of the Cenozoic increase in bivalve diversity, a major component of the marine record, suggesting that the diversity increase is likely to be a genuine biological pattern.     

Epidermal patterns of the lemma in some fossil and living grasses and their phylogenetic significance

Morphological study of fossil grass anthoecia of Berriochloa and Nassella collected from Miocene-Pliocene strata in Kansas has revealed well-preserved epidermal structure. This seems to be the first micromorphological information known from fossil grass floral bracts. The epidermal pattern on the lemma in the fossils and their living counterparts are evidence in support of the view that the North American species of Stipa of the section Hesperostipa Elias and species of Piptochaetium have a common ancestry in Berriochloa, and that species of both taxa have been distinct from species of the Nassella, Oryzopsis, and other Stipa since at least the Miocene or Pliocene.     

First fossil lamprey: a record from the Pennsylvanian of Illinois

A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the view that the common ancestor of lampreys and hagfishes lived prior to the Pennsylvanian.     

Early land animals in north america: evidence from devonian age arthropods from gilboa, new york

A new fossil site near Gilboa, New York, is one of only three where fossils of terrestrial arthropods of Devonian age have been found. The new Gilboan fauna is younger than the other two but richer in taxa. Fragmentary remains and nearly whole specimens assigned to Eurypterida, Arachnida (Trigonotarbida, Araneae, Amblypygi, and Acari), Chilopoda [Craterostigmatomorpha(?) and Scuterigeromorpha(?)], and tentatively to Insecta (Archaeognatha) have been found. The centipedes and possible insects may represent the earliest records known for these groups.     

Lichen-like symbiosis 600 million years ago

The fossil record of fungi and lichens is scarce. Here we report the discovery of lichen-like fossils, involving filamentous hyphae closely associated with coccoidal cyanobacteria or algae, preserved in marine phosphorite of the Doushantuo Formation (between 551 and 635 million years old) at Weng'an, South China. These fossils indicate that fungi developed symbiotic partnerships with photoautotrophs before the evolution of vascular plants.     

The rise of the rhizosolenid diatoms

The 18S ribosomal DNA molecular phylogeny and lipid composition of over 120 marine diatoms showed that the capability to biosynthesize highly branched isoprenoid (HBI) alkenes is restricted to two specific phylogenetic clusters, which independently evolved in centric and pennate diatoms. The molecular record of C25 HBI chemical fossils in a large suite of well-dated marine sediments and petroleum revealed that the older cluster, composed of rhizosolenid diatoms, evolved 91.5 +/- 1.5 million years ago (Upper Turonian), enabling an accurate dating of the pace of diatom evolution that is unprecedented. The rapid rise of the rhizosolenid diatoms probably resulted from a major reorganization of the nutrient budget in the mid-Cretaceous oceans, triggered by plate tectonics.     

The late Miocene radiation of modern Felidae: a genetic assessment

Modern felid species descend from relatively recent (<11 million years ago) divergence and speciation events that produced successful predatory carnivores worldwide but that have confounded taxonomic classifications. A highly resolved molecular phylogeny with divergence dates for all living cat species, derived from autosomal, X-linked, Y-linked, and mitochondrial gene segments (22,789 base pairs) and 16 fossil calibrations define eight principal lineages produced through at least 10 intercontinental migrations facilitated by sea-level fluctuations. A ghost lineage analysis indicates that available felid fossils underestimate (i.e., unrepresented basal branch length) first occurrence by an average of 76%, revealing a low representation of felid lineages in paleontological remains. The phylogenetic performance of distinct gene classes showed that Y-chromosome segments are appreciably more informative than mitochondrial DNA, X-linked, or autosomal genes in resolving the rapid Felidae species radiation.     

Fossil evidence for evolution of the shape and color of penguin feathers

Penguin feathers are highly modified in form and function, but there have been no fossils to inform their evolution. A giant penguin with feathers was recovered from the late Eocene (~36 million years ago) of Peru. The fossil reveals that key feathering features, including undifferentiated primary wing feathers and broad body contour feather shafts, evolved early in the penguin lineage. Analyses of fossilized color-imparting melanosomes reveal that their dimensions were similar to those of non-penguin avian taxa and that the feathering may have been predominantly gray and reddish-brown. In contrast, the dark black-brown color of extant penguin feathers is generated by large, ellipsoidal melanosomes previously unknown for birds. The nanostructure of penguin feathers was thus modified after earlier macrostructural modifications of feather shape linked to aquatic flight.     

A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber

The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution.     

Paleontology. Shaking the earliest branches of anthropoid primate evolution

Primates living today are believed to share a common ancestor that originated in either Africa or Asia. Fossil examples of such anthropoid ancestors have been found in both continents, so pushing back the origins to a single location has been controversial. In their Perspective, Jaeger and Marivaux discuss results reported in the same issue by Seiffert et al. that may put part of the controversy to rest. Seiffert et al. describe the earliest and most complete African anthropoid fossils from the Fayum desert region of Egypt. Cranial and dental fossils of two different small species were found, and their character, especially the features of the fossil teeth, suggests an ancient evolutionary history in Africa. At the same time, the phylogenetic analysis of Seiffert et al. is consistent with the view that African anthropoids immigrated from Asia at a very early date, probably before the late Paleocene (60 million years ago), possibly followed by later waves of immigration.     

Replication in plastic of three-dimensional fossils preserved in indurated clastic sedimentary rocks

A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves three steps: the dissolution of carbonate in fossiliferous rocks with hydrochloric acid, impregnation of resulting voids with liquid plastic, and dissolution of the rock matrix with hydrofluoric acid, leaving a concentrate of plastic-replaced fossils.     

Evolutionary significance of morphospecies: a test with cheilostome bryozoa

Much of the controversy concerning the theory of punctuated equilibrium stems from skepticism about the biologic validity of fossil morphospecies, particularly for supposedly simple invertebrate taxa like cheilostome Bryozoa that form the bulk of the fossil record. However, evidence from breeding experiments and protein electrophoresis shows that morphospecific identity of cheilostomes is heritable and that morphospecies are genetically distinct with no indication of morphologically cryptic species. Thus paleontologists can study cheilostome evolution at the species level, and previously demonstrated pattems suggesting punctuated speciation in cheilostomes should be taken at face value.     

Paleontology and Chronology of Two Evolutionary Transitions by Hybridization in the Bahamian Land Snail Cerion

The late Quaternary fossil record of the Bahamian land snail Cerion on Great Inagua documents two transitions apparently resulting from hybridization. In the first, a localized modern population represents the hybrid descendants of a 13,000-year-old fossil form from the same area, introgressed with the modern form now characteristic of the adjacent regions. In the second case, a chronocline spanning 15,000 to 20,000 years and expressing the transition of an extinct fossil form to the modern form found on the south coast was documented by morphometry of fossils dated by amino acid racemization and radiocarbon. Hybrid intermediates persisted for many thousands of years.     

Australopithecus garhi: a new species of early hominid from Ethiopia

The lack of an adequate hominid fossil record in eastern Africa between 2 and 3 million years ago (Ma) has hampered investigations of early hominid phylogeny. Discovery of 2.5 Ma hominid cranial and dental remains from the Hata beds of Ethiopia's Middle Awash allows recognition of a new species of Australopithecus. This species is descended from Australopithecus afarensis and is a candidate ancestor for early Homo. Contemporary postcranial remains feature a derived humanlike humeral/femoral ratio and an apelike upper arm-to-lower arm ratio.     

A molecular phylogeny for bats illuminates biogeography and the fossil record

Bats make up more than 20% of extant mammals, yet their evolutionary history is largely unknown because of a limited fossil record and conflicting or incomplete phylogenies. Here, we present a highly resolved molecular phylogeny for all extant bat families. Our results support the hypothesis that megabats are nested among four major microbat lineages, which originated in the early Eocene [52 to 50 million years ago (Mya)], coincident with a significant global rise in temperature, increase in plant diversity and abundance, and the zenith of Tertiary insect diversity. Our data suggest that bats originated in Laurasia, possibly in North America, and that three of the major microbat lineages are Laurasian in origin, whereas the fourth is Gondwanan. Combining principles of ghost lineage analysis with molecular divergence dates, we estimate that the bat fossil record underestimates (unrepresented basal branch length, UBBL) first occurrences by, on average, 73% and that the sum of missing fossil history is 61%.     

Significance of "tethyan" fossils in the american cordillera

Equatorial faunas of the ancient Tethyan seaway, which extended from western Europe to southeastern Asia, comprise some of the most diverse marine taxa in the fossil record. Comparable or identical "Tethyan" species that occur far from the Tethyan seaway in Paleozoic and Mesozoic rocks of the North and South American Cordillera have long been considered as a major biogeographic anomaly. Two leading theories to account for the occurrence of these anomalous "Tethyan" faunas in the Cordillera are that they were transported long distances to the east on tectonic blocks(suspect terranes that originated near the Tethys) or that they migrated westward via undiscovered marine corridors through continental areas of Pangea. An alternative model is that these "Tethyan" fauna were pantropic species that extended with attenuated diversities into the eastern proto-Pacific Ocean. This pantropic model can better account for the distribution patterns of many Paleozoic and early Mesozoic "Tethyan" species in the American Cordillera and provides a steady state hypothesis against which the other models can be tested. The distribution of pre-Cretaceous "Tethyan" faunas is similar to the known pantropic distribution of many Cretaceous and Cenozoic tropical biotas. During the Cenozoic, taxa were most diverse in the Tethys and Indo-West Pacific regions but extended with attenuated diversity to many parts of the equatorial Pacific Ocean, including the west coasts of North and South America. The eastern Pacific occurrence of many Indo-West Pacific species provides a modern analog for the occurrence of many anomalous "Tethyan" fossils in the American Cordillera.     

基于AFLP的菊属、亚菊属及其近缘属的属间关系

【目的】由于研究材料、地理分布等条件的限制,菊属(Dendranthema)、亚菊属(Ajania)及其近缘属的属间关系未得到很好解决。核糖体ITS区和叶绿体trnL/trnF间区等相关分子序列解析用于研究植物系统进化具有较大优势,但在菊属及其近缘属等相关类群间存在信息位点低的问题,而AFLP标记以其高多态性的优点在亲缘关系很近类群的系统演化研究中表现出一定的优势,因此本研究利用AFLP技术对菊属、亚菊属及其近缘属的属间关系进行研究,旨在分析和探讨菊属、亚菊属及其近缘属的系统关系,同时为菊花(D.×grandiflorum)等材料的遗传育种提供参考。【方法】利用9对荧光标记引物对东亚蒿亚族菊属、亚菊属及其近缘类群共50个分类单元进行AFLP分析,同时分别利用SPSS11.0软件采用非加权平均数UPGMA方法和PAUP*4.0b10软件采用最大简约法进行聚类分析。【结果】AFLP分析共获得1695个多态性条带。根据相似性系数,无论是整个蒿亚族及其近缘类群内部,还是菊属、亚菊属内部,均表现出较高的遗传多样性,种间分化明显。【结论】无论是UPGMA聚类分析结果还是构建的最大简约树,AFLP结果均将菊属和Arctanthemum先聚为一亚分支,各自形成两个种群,各自种群包含亚菊属的个别类群;亚菊属的大部分类群和太行菊属(Opisthopappus)形成另一亚分支,与菊属亚分支互为姐妹群形成菊属-亚菊属大分支。这说明菊属和亚菊属可能是由共同的祖先类群平行演化而来,其中亚菊属的多花亚菊(A.myriantha)、铺散亚菊(A.khartensis)等与菊属亲缘关系较近,而原产日本的矶菊(A.pacifica)、盐菊(A.shiwogiku)等是亚菊属中较进化类型;太行菊属的系统地位可能更接近于蒿亚族;短舌菊属(Brachanthemum)则被排除于菊属群之外。柳叶亚菊(A.salicifolia)、异叶亚菊(A.variifolia)等应从亚菊属中分离出来,支持单列成栎叶菊属(Phaeostigma)。     

Fossil mycorrhizae: a case for symbiosis

Vesicular-arbuscular mycorrhizae are significant in the physiology and ecology of extant vascular plants, and they may also have played a major role in the origin of the vascular land flora. The case for fossil vesicular-arbuscular mycorrhizae rests upon hyphae and chlamydospore-like bodies in several Paleozoic taxa, but fossil arbuscles are unknown to date. Specimens from the Triassic of Antarctica represent the first known occurrence of arbuscles in the fossil record.