John Meszaros:

Anomalocaris group. going clockwise from the lower left, the animals are: Anomalocaris canadensis, Amplectobelua symbrachiata, Hurdia victoria, Opabinia regalis, Kerygmachela kierkegaardi, Schinderhannes bartelsi, Pambdelurion whittingtoni and Laggania cambria.

Lobopods. Clockwise from top: Microdictyon sinicum, Hallucigenia sparsa, Onychodictyon ferox and Aysheaia pedunculata. Note, by the way, that what appear to be “eyes” on Microdictyon, Hallucigenia and Onychodictyon are actually sclerotized armor plates.


Up to a metre long with eyes on stalks and downward curving appendages, Anomalocaris was certainly a bizarre animal, yet it was also the top predator of is day. 

Anomalocaris, meaning “odd shrimp” is somewhat misleading. Upon its discovery in the Burgess Shale by Charles Doolittle Walcott in the early 1900′s. Anomalocaris’ mouth, appendages and body were though to be different species of animal. The appendages were mistaken for the body of a primitive prawn or shrimp like creature, hence the name meaning odd shrimp. Its mouth was thought to be an ancient type of jellyfish and it’s body, a species of sponge. It wasn’t until much later in the 1960′s that Walcott’s finds were reevaluated and Anomalocaris was finally pieced together. 

(above; Anomalocaris’ mouth mistaken for a jelly fish. You can see in the inner square the imprints of what would’ve been its teeth.)

This strange creature existed in the middle Cambrian period and is indeed a pivotal discovery. The Burgess Shale holds a huge amount of Cambrian life, during this period the diversity of life erupted, known as the Cambrian explosion. Life began to get more complex and developed and until the discovery of Anomalocaris it was unknown as to why evolution began to accelerate. 

The Cambrian saw the evolution of the eye take place, the ability of sight led to the development of active hunters and in response prey had to evolve better defences. This led to an evolutionary arms race between predator and prey. The development of sight and evidence of a skilled hunter in the Cambrian seas has led many researchers to pin this down as a trigger for the Cambrian explosion of life. 

During the time of Anomalocaris, life on land was almost non existent, anything the sea washed out was left to decay as nothing was there to feed on it.
Despite the emptiness on land, the oceans thrived with almost alien like creatures compared to what we are familiar with today and in these peculiar oceans, anomalocaris dominated.
This super predator could reach up to a metre long, but some specimens found in China have gone beyond that. Whatever its size, the animal was still up to 10 times longer than anything else at the time.


Watch this and keep in mind, this was made in 2009, so it was most likely done in total sicnerity. I love the internet sometimes.

Also, @delcat177, @bogleech, please look at this.


Trilobites are extinct Paleozoic marine arthropods which lived some 520 million years ago. Tens of thousands of different trilobite species have been identified from the fossil record. The great diversity of trilobites is quite astonishing and their fossils can be found on all continents. Some trilobites were just a few millimetres long while others could be greater than half a meter. Swimming, crawling and planktonic forms existed. Some species had huge eyes while others may have lost them all together. Among the great diversity both predatory and scavenging species can be found, however, trilobites themselves were a pray for nautiloids and extinct arthropods such as Anomalocaris (the bottom drawing).

Trilobite drawing from Système silurien du centre de la Bohême by Joachim Barrande

Anomalocaris drawing by Hannah Caine

Anomalocaris was a large Cambrian predator thought to have fed on trilobites using it’s powerful feeding appendages. However, later research has criticized this notion claiming that the appendages would have been soft and unable to penetrate the thick carapace of the trilobite. This suggests that Anomalocaris would have to feed on soft bodied organisms instead of other armored Cambrian fauna.

Chengjiang Biota - the dawn of the vertebrates, by Brian Choo:

“Strange creatures swarm in shallow sea off the northern fringes of the Gondwanan supercontinent. In the unimaginably distant future, this ancient seabed will be exposed as the Maotianshan Shale on the lush flanks of scenic hills in eastern Yunnan (Chengjiang, Jinning and Anning Counties), China. The fossils of the Maotianshan, collectively called the Chengjiang Biota, give a priceless glimpse into the Cambrian Explosion, the comparatively sudden appearances of a bewildering diversity of animal body forms that herald the arrival of the Phanerozoic. It represents one of a handful of Cambrian localities in the world, along with the Burgess Shale of Canada and Sirius Passet of Greenland, to feature extensive soft tissue preservation. The Chengjiang Biota currently includes well over 100 identified species, including creatures close to the ancestry of the vertebrate lineage.”


Walking with Monsters - “Water Dwellers”: Anomalocaris

Anomalocaris (literally, “strange shrimp”) was one of the first and largest of his family, Anomalocaridida. Anomalocaris was one of the most successful genera of the Cambrian period; he had a worldwide distribution and survived over 20 million years. Anomalocaris’ eyes, on the calibre of only a few modern insects, were compound with around 30 thousand lenses. He would swim above the ocean floor, find prey, and shred it in three rings of teeth.

Andy the Anomalocaris - Paleo Pals™
Adopt a cuddly Anomalocaris plush. A prehistoric plush sea-bug that is educational and fun. It’s CUTE! It’s WEIRD! It’s SCIENCE!

I KNOW most of my followers probably don’t care for these things but! There’s a new company called Paleo Pals that are planning to make adorable plushies of various extinct organisms often overshadowed by the dinosaurs, using data from actual fossils and studies! 

They just reached their kickstarter goals and will be ready to sell the first plush of their series, Andy the Anomalocaris, at around April! Like I said, they’re planning on doing other stuff (the next one is Diplocaulus), so if you think you might be interested you should check it out! 

It seems that anomalocaridids had two sets of flaps along their bodies – not only the swimming lobes originating from their undersides, but also a smaller set of dorsal flaps that appear to have been associated with gill-like structures.

And according to this paper Anomalocaris itself had a small head shield, too. These ancient stem-arthropods just keep on surprising us, don’t they?

The Abnormal Shrimp, Anomolocaris

This is Anomolocaris or the “abnormal shrimp”, one of the first large predators to appear on Earth. This beast roamed the seas during the Cambrian period, about 500 million years ago.

Anomalocaris had two long “arms” (you can vaguely see them on the left side of the fossil) which grabbed, killed & guided food into the circular mouth on the underside of this wonderful creature.

As much as I love dinosaurs, it’s great to look a bit further back and see what other special creatures lived on our amazing Earth.

Learn more!

  • Check out more wonderful shots from the ROM’s invertebrate palaeontology department HERE.
  • Learn more about the incredible Burgess Shale HERE.
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Anomalocaris by John Sibbick.

“It is rumored that this painting is actually based on Laggania,
a smaller relative of Anomalocaris. At top left you can see Pikaia,
the translucent ancestor of vertebrates”.

And you can see two Hallucigenias at the bottom.