The Vendian The Vendian
650 to 543 Million Years Ago the latest part of the Proterozoic
from the Dinosaur Collector
This is the time when the earliest-known animals evolved, and the continents had merged into a single super continent called Rodinia. Simple primitive life is known from 3.5 billion years ago.
Why did it take so long for complex life to evolve and what kick started this development? One interesting theory is called Ice Planet Earth. The planet froze over completely, isolating the remaining life into pockets and subjecting them to extreme conditions. Eventually, the ice melted and the combination of events proved to an evolutionary stimulus. The Ediacara fauna marks the beginning of visible life; including soft-bodied multi-cellular animals, like sponges, jellyfish, worms, and relatives of the arthropods. Just what if any is the relationship of these strange animals to modern animals is debated. There are two basic ideas; one being that the fauna dominated by animals with a thin quilted construction died out as a failed experiment. The thin quilted body plan could have allowed them to breath without developing complex internal structures. There don't seem to be any carnivores so they may have been especially vulnerable as predators evolved. The other camp sees them as predecessors to the animals seen later in the Cambrian. Fossils are rare and usually difficult to interpret, but as more finds come to light I expect a synthesis of the two views will arise. The Ediacara was named for the Ediacara Hills in Australia, north of Adelaide; the most famous Vendian fossil deposit.
update 12/27/06 proof 020606 rgk
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The Ediacara was named for the Ediacara Hills in Australia, north of Adelaide; the most famous Vendian fossil deposit.
Smithsonian Natural history Museum Edicara Diorama.
Dickensonia was an odd-shaped animal that was long and flat, no more than 2 ½ to 4 cm (1 to 1 ½ in) thick, with a tough exterior and a quilted construction. Scientists have no idea what exactly it was, or who it was related to. Nothing like it lives today. Dickensonia fossils are found around the world, and it surely was a major player in the early history of multi cellular life. Dickonsonia is known from Vendian rocks of southern Australia and northern Russia, and is often considered to be a segmented worm. Alternatively, it is purposed that Dickensonia was a floating filter feeder unrelated to any modern family. It appears to have grown by adding new segments.
Mawsonites spriggi maybe 9 - 10 cm, was originally thought to represent a medusa (jellyfish); this distinctive genus may well actually represent a sedentary filter feeder with the characteristic lobes being the attachment points.
Cadbury Yowie figures of a blue Giant Disc Jelly (Dickonsonia) from series 1 and red Mawsonites from series 2.
Charniodiscus fossils look like plant fronds, and it was a stationary filter feeder perhaps like a modern sea pen. Kimberella was a three centimeter wide animal, originally thought to be a box jellyfish. Since then, better fossils from the White Sea show a soft shell covering that make it look similar to a mollusk.......
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Charniodiscus and Kimberella from Nihon Hoso Kyokai (NHK) Miracle Planet series by Yujin based on the “Earth Evolution Encyclopedia" TV series from Japan. See the English language version of the Discovery Science channel.
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