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See beautiful fossils from top Cambrian sites around the world

You’ve heard of the Burgess Shale, but what about Sirius Passet?

By
7:00am, April 24, 2019
Anomalocaris

ANCIENT PREDATOR  The shrimplike arthropod Anomalocaris was a giant in its time, up to a meter in length. This fossil was found in pieces in the Burgess Shale — scientists once thought that pieces bearing its mouth, tail and feeding appendages came from three different creatures.

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For most of the nearly 3.5 billion years of documented life on Earth, creatures were simple, dominated by organisms such as bacteria, algae and fungi (SN: 10/13/18, p. 10).

Then, beginning about 541 million years ago, life quickly diversified into an array of new, complex forms. This flourishing, called the Cambrian explosion, took place within about 25 million years. Fossils from the period have been preserved in rocks at more than 50 known sites worldwide, the most famous of which is Canada’s Burgess Shale, discovered in 1909.

At five standout Cambrian sites, hundreds to thousands of different species were buried in the soft mud of long-ago seafloors. Rapid burial led to the exceptional preservation of soft-bodied animals as well as of soft tissues, such as brains, guts, eyes and skin, that typically don’t fossilize well. A newly reported site, Qingjiang in China, holds a wealth of exquisitely preserved soft-bodied animals such as jellyfish and comb jellies.

Here are some examples of the remarkable diversity of weird and wonderful Cambrian life found at these five sites:

1. Marrella

Canada’s Burgess Shale (1909)
508 million years old

Marrella fossils were some of the first found at the Burgess Shale and are the most common. At first labeled trilobites, the small, spiny sea creatures were later revealed to be a distinct type of arthropod.

Marrella fossil

2. Fuxianhuia

China’s Chengjiang (1984)
518 million years old

Fuxianhuia fossils offer what may be the best-known view of a Cambrian brain, tucked beneath a head shield. The organ could have evolved to help the marine arthropods process detailed visual information.

Fuxianhuia fossil

3. Ctenophore

China’s Qingjiang (2007; reported 2019)
518 million years old

The detailed preservation of this ctenophore, or comb jelly, shows rows of combs, which are plates of fused hairlike structures called cilia. Modern comb jellies use the combs to propel themselves through the water.

Ctenophore fossil

4. Anomalocaris

Australia’s Emu Bay Shale (1979)
514 million years old

Anomalocaris’ compound eyes (one shown) sported a stunning 16,000 lenses, at least. Few other arthropods, living or extinct, have had as many lenses (details shown in inset) as this marine predator.

Anomalocaris fossil

5. Halkieria

Greenland’s Sirius Passet (1984)
515 million years old

Meet Halkieria, a scaly, sluglike creature with bivalve shells on the front and rear of its body. The animal continues to defy classification; it has been linked to early mollusks and brachiopods, also known as lamp shells.

Halkieria fossil
Citations

D. Fu et alThe Qingjiang biota — A Burgess Shale–type fossil lagerstätte from the early Cambrian of South ChinaScience. Vol. 363, March 22, 2019, p. 1338. 

J.R. Paterson et al. The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana. Journal of the Geological Society. Vol. 173, January 2016. doi:10.1144/jgs2015-083.

A. Butler. Fossil Focus: The place of small shelly fossils in the Cambrian explosion, and the origin of animals. Palaeontology Online. Vol. 5, January 7, 2015.

R. R. Gaines. Burgess Shale-type preservation and its distribution in space and time. In: Reading and Writing of the Fossil Record: Preservational Pathways to Exceptional Fossilization. The Paleontological Society Papers, Volume 20. Cambridge University Press, October 18, 2014.

X. Ma et al. Complex brain and optic lobes in an early Cambrian arthropod. Nature. Vol. 490, October 11, 2012, p. 258. doi:10.1038/nature11495.

Further Reading

C. Gramling. Newfound fossils in China highlight a dizzying diversity of Cambrian life. Science News Online, March 21, 2019.

C. Gramling. Cholesterol traces suggest these mysterious fossils were animals, not fungi. Science News. Vol. 194, October 13, 2018, p. 10. L. Hamers. This ancient sea worm sported a crowd of ‘claws’ around its mouthScience News. Vol. 192, September 2, 2017, p. 4. 

A. Yeager. Fossil worm adds head to its spiny appearanceScience News. Vol. 188, August 8, 2015, p. 5. 

T.S. Feldhausen. Ancient brain fossils hint at body evolution of creepy-crawlies. Science News Online, May 12, 2015. 

S. Milius. Biology’s big bang had a long fuseScience News. Vol. 180, December 31, 2011, p. 12. 

A. Witze. Primordial bestiary gets an annexScience News. Vol. 178, September 25, 2010, p. 10. 

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