The Cambrian period was previously thought to be the first to contain multicellular life, but scientists have since discovered simple life in the Ediacaran period. The Cambrian period saw the emergence of complex life, including the forerunners of modern animal phyla. The period is known for the “Cambrian Explosion” of new organisms, including trilobites, echidnoderms, and the “strange crayfish” Anomalocaris. The Cambrian had a unique class of faunas, and is also known for the earliest trace fossils of land-walking animals.
The Cambrian period is a geological period extending from 542 to 488 million years ago. For many decades, it was famous for being the first geological period to contain multicellular life. Since 1967, however, scientists have determined that multicellular life existed prior to the Cambrian Period (in the Ediacaran Period), although most were quite simple and non-motile, consisting of fronds and pouches with a distinct tufted appearance. However, the Cambrian era was the first to contain truly complex life, including the forerunners of most modern animal phyla. In contrast, only a few representatives of modern phyla are found in the Ediacaran.
The Cambrian period begins with the appearance of the first trilobites and numerous fossils of what is called the small shell fauna, although some specimens of the latter were later found also in the late Ediacara. Small shell fauna and trilobites are among the earliest hard-bodied animals in the fossil record, and for centuries were the earliest known fossils of multicellular animals. The archaeocyathids (“ancient cups”) are another indicator of the beginning of the Cambrian, probable sponges resembling horn corals. Archaeocyathids were the first coral reef builders on the planet and thrived for about 23 million years until they went into a steep decline 520 million years ago.
As the Cambrian Period progresses, many amazing fossils emerge. So many fascinating new organisms appear in such an evolutionarily short time (10-15 million years) that the period has been dubbed the “Cambrian Explosion.” There’s Marella, a strange trilobite-like arthropod; the five-eyed Opabina, with a claw on a stalk protruding from her head; the “spiny snail” Wiwaxia, whose phylum is unknown; early echidnoderms; stem group crustaceans; the spiny-limbed Kerygmachela with its long cerci; the earliest jawless fish Myllokunmingia, which is the earliest known vertebrate or skull; grazing velvet worms; the iolites, enigmatic animals with a conical shell; monoplacophora, simple molluscs with only one shell; brachiopods, stationary stemmed animals that superficially resemble bivalves; and the Cambrian period “King of the Jungle”, the huge (for the time it was a meter long) “strange crayfish” Anomalocaris with its huge eyes and double feeding appendages on its head. Prior to this point, animal life had been rather dull and simple.
The Cambrian is distinctive in that it had a unique class of faunas, sometimes called “trilobite faunas” that never again dominated the Earth at any time. In the Ordovician Period, soon after, new animals appeared, including more evolved molluscs such as cephalopods, which swept away the old order. Even the animals got bigger; while most animals in the Cambrian were no larger than a few inches in length, animals a foot long and longer became much more common in the Ordovician and later periods.
Another thing the Cambrian Period is known for is the earliest known trace fossils of land-walking animals: Protichnites and Climatichnites, chevron-shaped traces up to 6 inches in diameter produced by a large arthropod or similar organism. a snail. These animals probably didn’t spend much time on land, but may have moved momentarily onto the wet sand from shore, to pick up food particles that would otherwise have remained untouched.
Protect your devices with Threat Protection by NordVPN
