The Precambrian (/ p r i ˈ k æ m b r i. ə n,-ˈ k eɪ m-/ pree-KAM-bree-ən, -⁠KAYM-; [2] or Pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon.

2025年1月3日 · Precambrian, period of time extending from about 4.6 billion years ago (the point at which Earth began to form) to the beginning of the Cambrian Period, approximately 541 million years ago. The Precambrian represents more than 80 percent of the total geologic record.

2024年11月23日 · Pre-Cambrian Animal Life. The time before the Cambrian period is known as the Ediacaran period (between 635-543 million years ago), the final period of the late Proterozoic Neoproterozoic Era. It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time.

The earliest multicelled animals that survived the Precambrian fall into three main categories. The simplest of these soft-bodied creatures were sponges.

Trace fossils of burrows and tracks are perhaps the best evidence for the existence of animals ancestral to modern forms in the Precambrian. Unlike the various fossils represented in the Vendian impressions, these animals would have possessed the key characteristic of most animals …

2021年2月28日 · It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time. Some protist species called choanoflagellates closely resemble the choanocyte cells in the simplest animals, sponges.

Cloudina, Namacalanthus, and Conotubus are skeletonized Precambrian animals which are also known in the early Cambrian (Shu, 2008). A number of worms such as Paleolina evenkiana and Planolites beverlyensis have been found at the end of …

Describe the features that characterized the earliest animals and when they appeared on earth

2019年6月1日 · But recent discoveries from Siberia, Namibia and elsewhere show that complex animals actually got their start millions of years before the Cambrian explosion, during the last chapter of the...

Nearly 4 thousand million years passed after the Earth's inception before the first animals left their traces. This stretch of time is called the Precambrian. To speak of "the Precambrian" as a single unified time period is misleading, for it makes up roughly seven-eighths of the Earth's history.