Anomalocaris

### Time

Early Cambrian (Yakutian) to Middle Cambrian (Miaolingian) (Atdabanian to Guzhangian), 520-499 Ma

### Taxon

Radiodont

***Anomalocaris*** (Ancient Greek ἀνώμᾰλος *anṓmalos* + καρίς *karís*) "unlike other shrimp" or "abnormal shrimp") is an extinct genus of anomalocaridid, which are, in turn, thought to be closely related to the arthropods along with *Opabinia* and *Marrella*. Other lobopods includes *Hallucigenia*, *Opabinia* and *Aysheaia*. Other carnivores of the Burgess Shale include *priapulids* (Stem-Group), *Hurdia*, *Peytoia* and *Opabinia*.

*Anomalocaris* reached a length of 6 1/2 ft (2 m), the size of an adult human.

## Description

*Anomalocaris* is thought to have been an apex predator, though it ate much softer prey items, presumably worms and basal vertebrates. It propelled itself through the water by undulating the flexible lobes on the sides of its body. Each lobe sloped below the one more posterior to it, and this overlapping allowed the lobes on each side of the body to act as a single "fin", maximising the swimming efficiency. The construction of a remote-controlled model showed this mode of swimming to be intrinsically stable,meaning that. *Anomalocaris* need not have had a complex brain to cope with balancing while swimming. The lateral lobes overlapped. The widest part of the body was on the third to fifth lobe; it narrowed towards its tail, and had at least 11 lobes in total. The more posterior lobes are difficult to discriminate, making an accurate count difficult. *Anomalocaris* had a large head, a single pair of large, possibly compound eyes, and an unusual, disk-like mouth. The mouth was composed of 32 overlapping plates, four large and 28 small, resembling a pineapple ring with the center replaced by a series of serrated prongs. The mouth could constrict to crush prey, but never completely close, and the tooth-like prongs continued down the walls of the gullet. Two large 'arms' (up to seven inches in length when extended) with barb-like spikes were positioned in front of the mouth. The tail was large and fan-shaped, and along with undulations of the lobes, was probably used to propel the creature. Cambrian waters. Stacked lamella of what were probably gills attached to the top of each lobe.

For the time in which it lived *Anomalocaris* was a truly gigantic creature, reaching lengths of up to one meter.

*Anomalocaris* had a cosmopolitan distribution in Cambrian seas, and has been found from early

to mid Cambrian deposits from Canada, China, Utah and Australia, to name but a few. Peytoia and Hurdia are other anomalocarids.

A long-standing view holds that *Anomalocaris* fed on hard-bodied animals, including trilobites. While its mid-gut glands strongly suggest a predatory lifestyle, its ability to penetrate mineralised shells has come under fire in recent years.

Some Cambrian trilobites have been found with round or W-shaped "bite" marks, which were identified in shape with the mouthparts of *Anomalocaris*. *Opabinia* could also fed on other creatures like *Aysheaia* and *Hallucigenia* but not *Anomalocaris* or a another giant predator like *Hurdia* with it's long gut.
They are the biggest animals of the Burgess Shale and bigger than other Early and Middle Cambrian animals.

## Appearance in other media

### Jurassic Park Franchise

* It appeared in Jurassic Park: Builder as an aquatic animal.