Tridymite pseudomorphs after wood in virginian lower cretaceous sediments

Fossil wood composed of tridymite is abundant in Patuxent (Lower Cretaceous) arkose on Hazel Run, Fredericksburg, Virginia. X-ray diffraction studies of the tridymite indicate that it has a disordered structure in which hexagonal close packing predominates. The specimens, which contain trace amounts of aluminum, iron, and other elements, are soft and fibrous, varying from white to shades of brown.     

Early evolution of avian flight and perching: new evidence from the lower cretaceous of china

Fossil bird skeletons discovered in Lower Cretaceous lake deposits in China shed new light on the early evolution of avian flight and perching. The 135 million-year-old sparrow-sized skeletons represent a new avian, Sinornis santensis, n. gen. n. sp., that preserves striking primitive features such as a flexible manus with unguals, a footed pubis, and stomach ribs (gastralia). In contrast to Archaeoperyx, however, Sinornis exhibits advanced features such as a broad sternum, wing-folding mechanism, pygostyle, and large fully reversed hallux. Modern avian flight function and perching capability, therefore, must have evolved in small-bodied birds in inland habitats not long after Archaeopteryx.     

Early cretaceous dinosaurs from the sahara

A major question in Mesozoic biogeography is how the land-based dinosaurian radiation responded to fragmentation of Pangaea. A rich fossil record has been uncovered on northern continents that spans the Cretaceous, when continental isolation reached its peak. In contrast, dinosaur remains on southern continents are scarce. The discovery of dinosaurian skeletons from Lower Cretaceous beds in the southern Sahara shows that several lineages of tetanuran theropods and broad-toothed sauropods had a cosmopolitan distribution across Pangaea before the onset of continental fragmentation. The distinct dinosaurian faunas of Africa, South America, and Asiamerica arose during the Cretaceous by differential survival of once widespread lineages on land masses that were becoming increasingly isolated from one another.     

Winteraceous pollen in the lower cretaceous of Israel: early evidence of a magnolialean angiosperm family

Pollen of the primitive angiosperm family Winteraceae has been discovered in the Aptian-Albian of Israel, extending the fossil record of this phylogenetically important family of flowering plants from the uppermost Upper Cretaceous back some 40 million years to the upper Lower Cretaceous. This appears to represent the earliest known record of a magnolialean angiosperm family and is convincing evidence for the existence in the Early Cretaceous of an extant family of angiosperms.     

Lower cretaceous sediments from the northwest pacific

The first occurrence of deep-sea Lower Cretaceous (Albian) sediments in the Pacific Ocean is reported from the Shatsky Rise at 31 degrees 51'N, 157 degrees 20'E. Seismic-profile records indicate that the core was taken between the extensive seismic reflectors A and B. Two hundred meters of unconsolidated sediment lies between the core site and basement (B) and suiggests that the sediment just above basement may be at least as old as Middle Jurassic.     

Fossil maize from panama

Wild maize, agricultural maize, and associated Manihot fossil polleni indicative of early agriculture after about 7300 years ago have been discovered in the Gatun basin, Panama. The course of risinig sea level in the Canal Zone during the past 11,300 years is calculated.     

Viviparity and intrauterine feeding in a new holocephalan fish from the lower carboniferous of montana

A new species of Lower Carboniferous holocephalan chondrichthyan, Delphyodontos dacriformes, is described from two fetal specimens. The well-developed slashing and piercing dentition, enlargement of the abdominal region, and fecal material indicate the probable evolution of intrauterine oophagy and viviparity in Paleozoic Chondrichthyes.     

金鱼寄生虫病的防治

金鱼寄生虫病是危害金鱼的主要疾病,素有"金鱼百病虫为先"之说.据福建省金鱼协会调查显示,每年由于寄生虫引发的病害占金鱼病害的74.6%,是金鱼养殖业健康发展之一大害. 由于金鱼终身栖息于水中,而且多是几种虫体共生、几个继发症并发,所以对其疾病的观察、诊断和治疗都有一定的困难,不易收到理想防治效果.笔者多年致力金鱼寄生虫病的研究,现将所得介绍于下.     

Iguanid lizard from the upper cretaceous of Brazil

Pristiguana brasiliensis, new genus and species, from the Upper Cretaceous Baurú Formation of Brazil, is the oldest fossil referable to the living lizard family Iguanidae. It resembles living primitive South American iguanids in some features, but also shows similarity to members of the related family Teiidae. Iguanid fossils do not appear in North America until the early Eocene, probably by waif dispersal from South America during the late Paleocene or early Eocene. A southern continental (Gondwanan) origin of iguanids is more plausible than the northern one often suggested.     

Early cretaceous angiosperm leaves from southern South america

Early angiosperm leaves from the Aptian (113 to 119 million years ago) Baqueró Formation of Patagonia have been found in a fossil flora dominated by more than 100 species of gymnosperms and pteridophytes. They may be the first early Cretaceous angiosperm leaves to be reported from southern South America and one of the few reported in the Southern Hemisphere. The leaves are large, lobate, craspedodromous, and dentate (A-1 teeth) and have ramified tertiary veins and random fourth-order venation. Several of these features have been found in coeval and younger strata elsewhere, but not in the same combination. They were probably a marginal component of the flora.     

Fossil land mammal from antarctica

A fossil land mammal, apparently the first found in Antarctica, belongs to the extinct marsupial family Polydolopidae. The fossils were recovered from rocks about 40 million years old on Seymour Island, in the northern Antarctic Peninsula. The newly discovered marsupials support theories that predicted their former presence in Antarctica and strengthen proposals that Australian marsupials perhaps originated from South American species that dispersed across Antarctica when Australia still was attached to it, prior to 56 million years ago.     

Terminal cretaceous extinction scenario for a catastrophe

All the biotic changes that occurred at the end of Cretaceous time, including the extinction of the dinosaurs, may be the result of a single terrestrial catastrophe. The Arctic spillover model, first proposed to explain the marine extinctions, would have caused a rapid and intense change in the earth's climate including a lowering of temperature and of precipitation. This change in climate may have triggered a series of ecological disasters that included the radical change in the distribution of vegetation on the earth as well as the extinction of the dinosaurs.     

Orbitolina, a cretaceous larger foraminifer, from flemish cap: paleoceanographic implications

The Tethyan larger foraminiferal genus Orbitolina has been found in the easternmost part of the western North Atlantic continental shelf at 46 degrees 30'N. All other known occurrences of the genus in North America are south of 33 degrees N. The species is Orbitolina conoidea Gras; its abundance in a grainsupported limestone indicates a tropical neritic environment and precludes the influence of Arctic waters in the Flemish Cap region in Early or Middle Cretaceous times.     

Reproductive and vegetative morphology of a cretaceous angiosperm

Recent collections from plant-bearing deposits of Cenomanian age in central Kansas have yielded angiosperm axes with helically arranged, seed-bearing, conduplicate carpels. Large leaves associated with these fruits are thought to represent parts of the same kind of plant because the leaves and fruits are the only plant fossils at this locality to have distinctive, morphologically identical, yellow bodies within their carbonaceous remains. These fossils provide a rare opportunity to study the morphology of an ancient angiosperm and illustrate the antiquity of certain features considered primitive by comparative angiosperm morphologists.     

Evidence for extreme climatic warmth from late cretaceous arctic vertebrates

A Late Cretaceous (92 to 86 million years ago) vertebrate assemblage from the high Canadian Arctic (Axel Heiberg Island) implies that polar climates were warm (mean annual temperature exceeding 14 degreesC) rather than near freezing. The assemblage includes large (2.4 meters long) champsosaurs, which are extinct crocodilelike reptiles. Magmatism at six large igneous provinces at this time suggests that volcanic carbon dioxide emissions helped cause the global warmth.     

Fossil peccary from the pliocene of South Africa

Pecarichoerus africanus, new species, from Langebaanweg, Cape Province, is the first fossil peccary to be described from Africa and represents the youngest record of the peccary family in the Old World.     

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.     

Qualitative indices of edible and inedible products obtained from fish in the lower Yenisei River basin

The results of biochemical investigations of samples of products obtained from burbot (Lota lota L.), perch (Perca fluviatilis L.), and pike (Esox lucius L.) inhabiting the lower reaches of the Yenisei River basin are given. Biologically active substances—macro- and microelements, fatty acids, amino acids, and vitamins—are analyzed.