Cambrian Period Essay

The Cambrian Period is the start of the Paleozoic Era (1). It is the first geologic time period of this era and lasted about 55 million years (2). The Cambrian Period starts at around 543 million years ago. The start of this period is marked with the first appearances of worms that dug horizontal burrows. The Cambrian Period ends with a great extinction event that occurred 490 million years ago (1). This period is known for an incredible evolutionary burst that occurred during its time. This is known as the Cambrian Explosion (3). This is when many major groups of animals first appear in fossil record (5). One type of animal that evolved during this time period is the chordates (1). These include vertebrates, which humans belong to. The earliest known

This fossil is of a Halkieria, which is a slug-shaped animal with shell caps on both ends and smaller armor plates covered the rest of the body. One fossil of this species was found curled up in a defensive position, similar to a pillbug, which implies that there was a predator to defend against. At the start of the Cambrian Period, the Earth was cold but was gradually getting warmer. There was only one continent at this point, but by the early middle of the Cambrian Period tectonic activity broke the continent into two (1). This split is what later became the Pacific Ocean (4). The continent continued to break up into smaller continents during the Cambrian Period (5). This created multiple continents, including four big continents in which one contained what would become North America and Greenland, another contained western Europe and Scandinavia, and another contained Australia, Antarctica, Africa, India, and South America. These tectonic events caused flooding of parts of many continents (4). During this, no life forms existed on land, all creatures were aquatic