Biology, 25.02.2021 01:50 areynaguzman100
Intervals of geologic time are bound by important events, like mass extinctions or the appearance of animals with hard parts. The first single-celled organisms appeared about 3.5 billion years ago. Many sea animals first show up in the Cambrian period of the Paleozoic era. That was about 545 million years. It is sometimes referred to as the Cambrian explosion because it happened relatively quickly. It lasted just over 50 million years. The next period, , the Ordovician, ended with mass extinctions of 60% of all marine invertebrates. Dinosaurs wouldn't appear for over 200 million years, during the Jurassic period in the Mesozoic era. Based on the passage, in geology, 50 million years is A an era. B not considered a very long time. C too short for any significant events to occur. D about how long dinosaurs were on the planet.
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Biology, 22.06.2019 02:30, robert7248
The idea that all living things are made up of cells is considered scientific law. this means the idea is an emerging scientific idea that has a logical explanation. has been tested with similar results at least twice. is supported by scientific consensus and a large amount of evidence. has been rejected only once by the scientific community
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Biology, 22.06.2019 10:40, karlyisaunicorn
Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above
Answers: 1
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