Anomalocaris

***Anomalocaris*** ("abnormal shrimp") is an extinct genus of anomalocaridid, which are, in turn, thought to be closely related to the arthropods. The first fossils of *Anomalocaris* were discovered in the *Ogygopsis* shale by Joseph Frederick Whiteaves, with more examples found by Charles Doolittle Walcott in the famed Burgess Shale. *Anomalocaris* has two known species: ***A. canadensis*** and ***A. daleyae***.

The recently discovered species *A. daleyae* is known from the somewhat older Emu Bay Shale of Australia. the frontal appendages were the only known fossilized parts and misidentified as the body parts of other creatures.

## Description
*Anomalocaris* lived in the Cambrian period, which was a long time before dinosaurs. This makes *Anomalocaris* very old, so their body parts haven't evolved to be as detailed as modern animals.

### Physical appearance 
*Anomalocaris* still had compound eyes which were very big and complex compared to other animals in the earlier parts of the Cambrian, and also had segmented (has many sections) front appendages which were used to grasp its prey like arms. So while *Anomalocaris* was around the size of a small lobster, it still was a very good apex predator for its time.

### As a different animal 
*Anomalocaris* was misidentified many times, as the mouth, front appendages and trunk (the rest of its body) were discovered separately multiple times, leading scientists to think for a while that these parts of *Anomalocaris* were, in fact, of three different animals, with the mouth thought to be a jellyfish, the front appendages thought to be a shrimp and the trunk thought to be a sea cucumber or sponge.

### Size comparison 
*Anomalocaris* was huge in comparison to other animals. A complete specimen of *A. canadensis*, called **ROMIP 51211**, measures up to 20.5 cm (8.1 in) long). The newly discovered *A. daleyae* from the Emu Bay Shale is larger than *A. canadensis*, with the biggest appendage measuring up to 18.3 cm (7.2 in) long, which belongs to an individual measuring between 34.8–51.2 cm (1.14–1.68 ft) long.

### Early discovery 
*Anomalocaris* fossils were first collected in 1886 He found two unknown specimens. The fifty specimens were examined and described in 1892 by GSC paleontologist Joseph Frederick Whiteaves.
Whiteaves thought they were the abdomens of phyllocarids, and made the name ***Anomalocaris canadensis***. He describes the things:

"Body or abdominal segments, which, in all the specimens collected, are abnormally flattened laterally, a little higher or deeper than long, broader above than below, the pair of ventral appendages proceeding from each, nearly equal in height or depth to the segment itself... The generic name *Anomalocaris* (from *ανώμαλος*, unlike,—*καρίς*, a shrimp, *i.e.*, unlike other shrimps) is suggested by the unusual shape of the uropods or ventral appendages of the body segments and the relative position of the caudal spine."

### *A. daleyae* 
In 2011, compound eyes of *Anomalocaris* were found from a dig at Emu Bay Shale on Kangaroo Island, Australia; with compound eyes; proving that *Anomalocaris* was really an arthropod. This was later identified in 2023 as a newly discovered species of the genus, ***A. daleyae***.
## Behaviour
*Anomalocaris* lived in the sea, like most of the plants (which were really small algae in the Cambrian) and animals back then. Recently, people now think that *Anomalocaris* didn't hunt trilobites and other benthic animals that lived on the sea floor, but instead swam after nekton like basal chordates (animals that can control how they move underwater, unlike plankton). 

## Related pages
* Opabinia—a related genus to *Anomalocaris*
* Cambroraster

## Sources 
## Other websites 
* The anomalocaris homepage featuring swimming animation
* https://undsci.berkeley.edu/this-is-not-the-shrimp-youre-looking-for/