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These Bizarre Sea Monsters Once Ruled the Ocean

Hallucigenia worm illustration

The <em>Hallucigenia sparsa</em> worm had quite a grin — a circular mouth lined with needlelike teeth. More teeth lined the inside of its mouth and throat, researchers found.

(Image credit: Danielle Dufault)

The Hallucigenia sparsa worm had quite a grin — a circular mouth lined with needlelike teeth. More teeth lined the inside of its mouth and throat, researchers found.

Hallucigenia worm fossil

The <em>Hallucigenia sparsa</em> worm was uncovered in Canada's Burgess Shale, one of the world's richest fossil sites.

(Image credit: Jean-Bernard Caron)

The Hallucigenia sparsa worm was uncovered in Canada's Burgess Shale, one of the world's richest fossil sites.

Ancient Arthropod

arthropod-fossil

(Image credit: Yie Jang (Yunnan University))

The Cambrian period saw a rise in complex life forms like this early arthropod from simple multi-cellular creatures.

Well-preserved limbs

arthropod-fossil

(Image credit: Yie Jang (Yunnan University))

Because the ancient arthropods, fuxhianhuiid, were fossilized in a flipped position in a region of Southwest China, they are only example of preserved feeding limbs in this species.

Nervous System

cambrian-nervous-system

(Image credit: Yie Jang (Yunnan University))

A site in Southwest China has revealed a rich trove of creatures from the Cambrian period, including the only example of a nervous system that extends past the head.

Rich fossil mine

arthropods, including a trilobite and a chelicerate

(Image credit: Smithsonian Institution, Courtesy of Douglas Erwin)

Arthropods from the Burgess shale, such as the trilobite Olenoides and a chelicerate called Sidneyia, exploded in morphological diversity following the so-called Cambrian Explosion.

Iconic species

(Image credit: The Burgess Shale Geoscience Foundation - Field, BC - Canada)

Trilobites are a common find at the Burgess Shale.

Trilobite Traffic

chain of trilobite fossils

(Image credit: Adrian Kin)

A chain of trilobites preserved in Poland's Holy Cross Mountains.

Prickly creature

(Image credit: Marianne Collins (C)AAAS/Science-2007)

Paleontologists have also identified a a slug-like creature covered with prickly armor at the Burgess Shale

Tulip-shaped animal

Tulip-like filter feeder from the Burgess Shale.

(Image credit: © Royal Ontario Museum)

The Cambrian also saw the rise of larger creatures, such as this 2-foot-long ancient shrimplike creatures called anomalocaridids, which had spiny head limbs for catching prey