| 词汇 | example_english_fossil |
| 释义 | Examples of fossilThese examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. Chitinozoans and a few graptolites were found in the unit, but no other fossils. However, their exact stratigraphic relation to the trace fossils is not clear. In this chapter typical examples of the kinds of fossils most commonly encountered are illustrated by beautiful specimens. At the opposite end of the scale from the phylum is the smallest unit of classification usually used for fossils: the species. The small, lentil-shaped fossils are a separate form of the same species. Most bivalve fossils are a few centimetres long; the ideal size for collecting. Here, no vertebrates at all could be found, the fossils consisting only of invertebrates such as the trilobites. However, this technique only provides an external morphological description of putative fossilized cells and is incapable of distinguishing between abiotic fossils of similar morphologies. The conditions leading to preservation of these fossils are undoubtedly rare but not entirely unique. The fossils were found in the middle part of the road-cut. The use of trace fossils as proxies for the presence of animals allows palaeoecological data to be gathered in the absence of body fossils. A biostratigraphic correlation was possible as the fauna was not associated with other fossils and was unique. The illustrations are mostly high quality black-and-white photos but there are also 16 pages of excellent colour photos of fossils and their living counterparts. The zone is 170 m thick, and ammonoids and other fossils occur as imprints in mudstones and as shell-rich layers in sandy turbidites. The book is far more than a mere description of sedimentary indicators of facies and of fossils as tracers of environment. There are then 12 chapters introducing the major groups of fossils. Biofilms can stabilize sediment and promote the preservation of soft-bodied fossils. As it was impractical to analyse all of the individual fossils, a sample of the collected material was taken. The absence of fossils, for whatever reasons, is therefore problematic. Catalogue of the type, figured and cited fossils. An improved method of analyzing distortion in fossils. The real meat of this book is the 11 chapters dedicated to fossils of particular higher taxa. From the data available on the tuff samples so far, the recognition of species has proven problematic due to the fragmentary nature of the fossils. Statistical and imaging methods applied to deformed fossils. Ichnological analysis was focused on ichnotaxonomy, vertical distribution of trace fossils, and cross-cutting relationships. She claims that 'four errors about ancient experiences with fossils recur in paleontological histories'. The association of sediments and fossils became unstable unless it was recorded and authenticated. He also trained in the observation of fossils, prehistoric remains, and geological strata. In addition, agricultural practices in which coastal farmers cyclically turn over the soil have disrupted fossils and artefacts interred in the earth. Nothing in our account precludes "empirical research on fossils, artefacts, genes, and climates" as these relate to religious beliefs and practices. Contemporary examples of marriages by capture are regarded as living fossils of a once-universal practice. One such is the naming of trace fossils, which is dealt with here in some detail. Additionally, there has been a lot of interest in the vertebrate palaeontology with attempts to integrate body and trace fossils. The objectives of naming trace fossils are to provide stability and to maximize their information potential. Moreover, the ichnofauna determinations have all been carried out on core with many examples of the trace fossils illustrated in core photographs. Stratigraphically diagnostic fossils are scarce or absent in many of these clastic sequences, which furthermore differ markedly in lithological succession between different outcrop areas. The extant phylogenetic bracket and the importance of reconstructing soft tissues in fossils. Palynologically, the samples with the best-preserved fossils generally came from the black shales or layers directly sub-/superjacent. Both fossils are poorly and indistinctly preserved as impressions lacking organic carbon. Goldring sets out to introduce the undergraduate or new research student to various techniques of studying fossils in the field. Thus, we are taken through examples of log preparation, interpretation of trace fossils and graphical correlation. In this particular locality, trace fossils occur commonly in the same horizon as gogiid faunas. The pale green tuffaceous mudstone beds are medium bedded and contain abundant radiolarian fossils. However, we believe that detection of stratigraphic incongruence might point to the need for additional investigations (examination of new fossils and reanalysis of characters). In particular, certain grammatical phenomena appear as "fossils" of earlier stages. Such very old bio-sedimentations as stromatolites or microbialites are known among the oldest terrestrial fossils and testify to the earliest terrestrial bioactivity. The freshness of possible fossils depends mostly on the chemical environment. The genomic tag hypothesis : modern viruses as molecular fossils of ancient strategies for genomic replication, and clues regarding the origin of protein synthesis. We consider this technique to be an ideal tool for the detection, description and characterization of microbial fossils. Could there be fossils left from that time ? My only critique, and a minor one, is that the time axis of trace fossils is barely mentioned. Compared to the earlier edition there is an added chapter on applications of trace fossils, as reflected by the expanded subtitle. Included are discussions of associations of trace fossils and their description, quantification and interpretation. Typically, each sample included tens of discrete fossils. Named from the small size of the fossils. Our fossils show no evidence of having pervasively grown through the sediment and as such appear not to be protists or microbial colonies. Below the surface, trace fossils are abundant and relatively diverse. Bioturbation and presence of body fossils indicate an oxic bottom environment. Additionally, this implies permineralization of the rock occur red only after the fossils were transported and deposited. However, all the fossils are fragmentary and difficult to classify. Finally, the fact that the fossils are preserved as fusain, indicating the presence of extensive wildfire in the area, goes against a mangrove interpretation. In general the book offers a useful and frequently well-illustrated guide to dinosaur and pterosaur fossils. No marine fossils were found in the logged section, nor was there any clear evidence of bioturbation. Abundant horizontal exichnial trace fossils occur on the trough surfaces. Often trace fossils are the sole biogenic tools for this purpose. While myths concerning the bones of vertebrates are the mainstay of the book, invertebrate fossils are not neglected. Chapter 10 is a book in itself with 175 pages devoted to the recognition of fossils in thin section; this is an invaluable review. Collection of additional fossils within a detailed stratigraphic framework would resolve this issue. The mine was worked for a decade, from 1973 to 1982, purely for its fossils. Unfortunately a detailed taphonomy of the fossils is difficult because the mine is no longer accessible. The economic exploitation of phosphatic deposits has yielded a great number of vertebrate fossils. Understanding the processes of fossilization is vital to the interpretation of fossils themselves, especially of geochemical fossils. The important points in the ensuing debate centred on the legal right to collect fossils at sites, and the sustainability of certain sites. Because of variations in the biostratigraphic utility of different kinds of fossils, taxonomic groups are discussed sequentially. The collection of fossils within our increasingly bureaucratic world needs encouragement and also proper approaches. The book gives the very nar row impression that stratigraphy is entirely about nomenclature and cor relation, and that palaeontologists merely list biostratigraphically useful fossils. The abundant trace fossils indicate a prolific infaunal activity between episodes of highenergy deposition. The discovery of fossils was not a momentous happening, but an act that stretched itself over a period of time. However, it had now become important to glean every single notice of fossils in the region. The infilling of fissure 2 contains conglomerates in which the contemporaneous terrestrial to marine vertebrate fossils are in a ratio of > 1000:1. Upon close scrutiny, however, nothing of that kind is to be found on the sites or among the fossils. The fossils known from each unit are listed and critically evaluated for their age significance. Two processes may be responsible for the lack of informative plant fossils. The local stage names persist in this region because of a lack of biostratigraphically informative fossils that would enable use of the internationally defined system. The palynological assemblages are very clearly present above, below and co-bedded with the reptile fossils. Evolution of behavior as expressed in marine trace fossils. No trace fossils have been found as epichnia on the bed tops. Despite pteridosperm foliage occurring commonly as fossils, examples with attached pollen-organs are extremely scarce; even isolated pteridosperm pollen-organs are very rare. However, a more detailed mor phological study of these fossils to elucidate their status is strongly recommended. Based on fossils and bioturbation, this is an open marine facies association. Primary indicators are numerous trace fossils, which generally occur at parting surfaces of the fine-grained sandstones and shales. Preservation is rather poor due to complete carbonization and advanced degradation of fossils, which can only be observed in reflected light. Morphological simplicity of these fossils and the lack of diagnostic features prevent a specific assignation of the material. The absence of biostratigraphically useful fossils that might allow correlation of the disparate sections has made this proposal difficult to test. However, the strata and fossils of this interval are not complete in many parts of the world. The systematics of vertebrate trace fossils has been the subject of a long debate which derives from the origins of ichnology. The depositional age of this series is not known owing to the lack of dateable fossils. As a palaeontologist he provides a great deal of valuable information on the fossils of the island, and also on reconstructing past environments. These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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