Mesozoic era
Mesozoic era
| Noun | 1. |  Mesozoic era - from 230 million to 63 million years ago |
| 单词 | mesozoic era | |||
| 释义 | Mesozoic eraMesozoic era
Mesozoic eraSee also: Geologic Timescale (table)Geologic Timescale Mesozoic era(mĕz'əzō`ĭk) [Gr.,=middle life], major division of geologic time (see Geologic TimescaleGeologic TimescaleEra Period Epoch Approximate duration (millions of years) Approximate number of years ago (millions of years) Cenozoic Quaternary Holocene 10,000 years ago to the present Pleistocene 2 . ..... Click the link for more information. , table) from 65 to 225 million years ago. Great crustal disturbances that marked the close of the Paleozoic and the beginning of the Mesozoic eras brought about drastic changes in the topography of North America. The Appalachian geosyncline, or downward thrust of the earth's crust, was replaced by the Appalachian Mts., and the eastern part of the continent was elevated during most of the era. The Appalachians were subjected to erosion, the products of which were deposited along the Atlantic coast, which had become a lowland region, or in the ocean beyond. Aside from the Appalachians, the other dry (consistently) areas of the continent were the Canadian Shield, the Antilles areas, and a mountain range elevated in part of the Cordilleran geosyncline. The Mesozoic tectonic activity included numerous subduction zones, such as those along the Pacific margin of the supercontinent Pangaea. Later, Pangaea began to split into the supercontinents of Gondwanaland and Laurasia, and N Africa began to rift apart. By the late Mesozoic, tectonic activity increased dramatically: the new Indian Ocean began to open, the Atlantic Ocean began to open along an extensive rift zone separating the Americas from Europe and Africa (see seafloor spreadingseafloor spreading, theory of lithospheric evolution that holds that the ocean floors are spreading outward from vast underwater ridges. First proposed in the early 1960s by the American geologist Harry H. ..... Click the link for more information. ). The life of the Mesozoic was dominated by the reptiles that evolved into the large land-dwelling dinosaurs of the Jurassic and Cretaceous periods. Flying reptiles and birds first appeared during the Mesozoic. Mammals probably evolved from some common ancestor of the reptiles early in the Triassic Period, but were subordinate to the reptiles until the end of the era, when the dominance of reptiles was ended by the extinction of the dinosaurs. Conifers dominated the plant life, with modern pines and sequoias first appearing. Flowering plants, deciduous trees, and grasses also appeared during this era. Mesozoic eraMesozoic erathe geological era that began 225 million years ago and lasted about 155 million years. The era includes the CRETACEOUS PERIOD, JURASSIC PERIOD, and TRIASSIC PERIOD. During this era GYMNOSPERMS became dominant plants, dinosaurs became the dominant animals, reptiles (Pterosaurs) conquered the air, and birds and mammals evolved.Mesozoic era
Synonyms for Mesozoic era
|
|||
| 随便看 |
|
英语词典包含2567994条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。