Answer:
The Cambrian Explosion!
Explanation:
Sounds exciting right?
WELL IT IS!
The Cambrian explosion or Cambrian radiation was an event approximately 541 million years ago in the Cambrian period when practically all major animal phyla started appearing in the fossil record. It lasted for about 13 – 25 million years and resulted in the divergence of most modern metazoan phyla.
So in your case the answer would be 542 million years ago or the first animals with exoskeletons appear.
A collection of pitches arranged in ascending or descending order is called a scale.
<h3>What is a
scale?</h3>
A scale can be described as the any set of musical notes which is been ordered as a result of the fundamental frequency or pitch.
It should be noted that a A scale that is been ordered as a result of the increasing pitch is an ascending scale, and the one following the decreasing pitch is a descending scale., hence collection of pitches arranged in ascending or descending order is called a scale.
Learn more on pitches at:
brainly.com/question/4945474
#SPJ1
Historians rely on primary sources because these sources because it provide eyewitness account of events
The Burj Khalifa building also known as Burj Dubai is the tallest building in the world. Designed by Adrian Smith, it rises 828 meters above the city of Dubai in the United Arab Emirates.
