| 词汇 | trilobite |
| 释义 | trilobite noun[ C ] biology, geology specializeduk /ˈtraɪ.lə.baɪt/ us /ˈtraɪ.loʊ.baɪt/ a simple, flat sea creature that lived in the earliest period of life on earth, with a hard outer layer and a body in three parts三叶虫 De Agostini Picture Library /De Agostini Editoria/GettyImages Sea creatures abalone amphipod anemone barnacle barrier reef cowrie crab cray crayfish crustacean littleneck clam lobster marron mollusc mussel shellfish shipworm shrimp snow crab soft-shell clam Examples of trilobitetrilobite Some, such as those on brachiopods, trilobites and chitinozoa, record information pooled by many specialists; others are the work of one or a few workers. Though commonly observed, blindness in trilobites remains difficult to explain in terms of adaptation. The trilobites are disarticulated and generally fragmentary, which may indicate that they have been subjected to post-mortem transport. Distribution of trilobites within these formations is random, and boundaries between the lithostratigraphic units are typically not exposed. The trilobite was collected from a bed that is 28 cm thick, composed of limestone (moderately resistant micritic mudstone to wackestone). The similarities are observed on the genus level, whereas on species level, trilobites from all these areas display a distinct endemicity. The latter is well illustrated, with comments on faunas and facies, and listing the trilobites which have been found in particular formations and members. Many specimens are incomplete, and this, together with their co-occurrence with fragmentary trilobites, spicules of sponges, sclerites of chancelloriids and other shelly organisms, suggests transportation. Wellpreserved, non-abraded brachiopods and club-like bryozoans are abundant, whereas gastropods and disarticulated trilobite cuticles are sparse. It also increases our knowledge of the evolution of early ontogeny in proetoid trilobites. We could all write of our first trilobite find. These cor relations are based on small shelly fossil and trilobite taxa. Skeletal grains are disarticulated and generally from brachiopods and trilobites. Much scarcer are other types of bituminous skeletal limestones, which consist mostly of crinoid ossicles associated with rare brachiopod and trilobite remains. Despite extensive searching, no specimens were found stratigraphically lower in the outcrop, and lack of exposure prevented sampling just above the trilobite occurrence. 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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