Search results
People also ask
What happened during the Cambrian era?
When did the Cambrian Period End?
When did temperatures increase in the Cambrian era?
Why is the Cambrian Period important?
Jul 4, 2024 · Cambrian Period, earliest time division of the Paleozoic Era and Phanerozoic Eon, lasting from 538.8 million to 485.4 million years ago. The Cambrian System, named by English geologist Adam Sedgwick for slaty rocks in southern Wales and southwestern England, contains the earliest record of abundant and varied life-forms.
- Fauna
Cambrian Period - Fauna, Fossils, Evolution: Cambrian...
- Paleoclimate
Cambrian Period - Fossils, Paleoclimate, Evolution: Global...
- The Cambrian Environment
The geographic reconstruction is based on integrated...
- Cambrian Rocks
Cambrian Period - Fossils, Rocks, Animals: Cambrian rocks...
- Ordovician
Ordovician Period, in geologic time, the second period of...
- Proterozoic Eon
Proterozoic Eon, the younger of the two divisions of...
- Silurian
Silurian Period, in geologic time, the third period of the...
- Cambrian Explosion
Cambrian explosion, the unparalleled emergence of organisms...
- Fauna
- Overview
- Cambrian Explosion
- Evolutionary Update
Learn more about a time period marked by an intense burst of evolution.
The Cambrian period, part of the Paleozoic era, produced the most intense burst of evolution ever known. The Cambrian Explosion saw an incredible diversity of life emerge, including many major animal groups alive today. Among them were the chordates, to which vertebrates (animals with backbones) such as humans belong.
Nevertheless, the scale of the Cambrian Explosion is likely exaggerated due to the proliferation of hard-bodied animals that fossilized much more readily than their soft-bodied precursors. These included brachiopods, which lived in shells resembling those of clams or cockles, and animals with jointed, external skeletons known as arthropods—the ancestors of insects, spiders, and crustaceans. These toughened-up creatures represented a crucial innovation: hard bodies offering animals both a defense against enemies and a framework for supporting bigger body sizes.
The iconic arthropods of the Cambrian were the trilobites, which left a huge number of fossils. Trilobites had flattened, segmented, plated bodies that helped to protect them in seas that were increasingly filled with predators. With many varieties and sizes—they ranged from a millimeter to more than 2 feet (0.6 meters) in length—trilobites proved among the most successful and enduring of all prehistoric animals. More than 17,000 species are known to have survived until the mega-extinction that ended the Permian period 251 million years ago.
A predator of the Cambrian was the giant, shrimplike Anomalocaris, which trapped its prey in fearsome mouthparts lined with hooks. Even stranger was the five-eyed Opabinia, which caught its victims using a flexible clawed arm attached to its head. These animals hunted along the seabed, where colonies of archaic sponges grew on organic, mineral structures formed by the activity of cyanobacteria. The sponges added to these reef habitats by building supporting skeletons from calcium carbonate, which they collected from the water.
The earliest known primitive chordate is Pikaia gracilens, a wormlike creature that swam in middle Cambrian seas. Fossils found in the Burgess Shale of British Columbia show traces of a notochord (a rodlike primitive backbone), a significant step in the evolution of vertebrates.
Cambrian sediments found in Canada, Greenland, and China have yielded rarely fossilized soft-bodied creatures such as marine worms buried during undersea mud avalanches. Representing the oldest known backboned animals with living relatives, the fossils showed that our vertebrate ancestors entered the evolutionary story some 50 million years earlier than previously thought.
The end of the Cambrian saw a series of mass extinctions during which many shell-dwelling brachiopods and other animals went extinct. The trilobites also suffered heavy losses.
The Cambrian (/ ˈ k æ m b r i. ə n, ˈ k eɪ m-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 485.4 Ma.
May 27, 2016 · The Cambrian Explosion was a dramatic burst of evolutionary changes in life on Earth. During the Cambrian Period, which began about 540 million years, trilobites were the dominant species.
- Mary Bagley
Jun 28, 2024 · Cambrian explosion, the unparalleled emergence of organisms between 541 million and approximately 530 million years ago at the beginning of the Cambrian Period. The event was characterized by the appearance of many of the major phyla (between 20 and 35) that make up modern animal life.
Jul 4, 2024 · The geographic reconstruction is based on integrated geologic and biological evidence. Fossils in continental-shelf deposits indicate the presence of at least three major faunal provinces (or biogeographical regions) during much of the Cambrian Period.
The Cambrian world was bracketed between two ice ages, one during the late Proterozoic and the other during the Ordovician. During these ice ages, the decrease in global temperature led to mass extinctions.
