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The evidence of plant evolution changes dramatically in the Ordovician with the first extensive appearance of embryophyte spores in the fossil record. The earliest terrestrial plants lived during the Middle Ordovician around 470 million years ago , based on their fossils found in the form of monads and spores, with resistant polymers in their ...
The Early Ordovician is the first epoch of the Ordovician period, corresponding to the Lower Ordovician series of the Ordovician system. It began after the Age 10 of the Furongian epoch of the Cambrian and lasted from 486.85 to 471.3 million years ago, until the Dapingian age of the Middle Ordovician .
The Ordovician–Silurian extinction events may have been caused by an ice age that occurred at the end of the Ordovician Period, due to the expansion of the first terrestrial plants, [54] as the end of the Late Ordovician was one of the coldest times in the last 600 million years of Earth's history.
The Sandbian is the first stage of the Upper Ordovician.It follows the Darriwilian and is succeeded by the Katian.Its lower boundary is defined as the first appearance datum of the graptolite species Nemagraptus gracilis around 458.2 million years ago.
The later (or upper) part is defined by the first appearance of the graptolite Normalograptus persulptus, and the Normalograptus persulptus biozone lasts from then until the end of the Hirnantian. This also marks the end of the Ordovician Period. These biozones allow for additional refinement in dating events occurring within the Hirnantian Stage.
A critically endangered butterfly that lives in the southernmost part of Florida thrives in certain years. Researchers turned to weather data to find out why, and the answer brought a surprise twist.
The fossil history of flowering plants records the development of flowers and other distinctive structures of the angiosperms, now the dominant group of plants on land.The history is controversial as flowering plants appear in great diversity in the Cretaceous, with scanty and debatable records before that, creating a puzzle for evolutionary biologists that Charles Darwin named an "abominable ...
The Darriwilian is the upper stage of the Middle Ordovician.It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species Undulograptus austrodentatus around 469.4 million years ago.