Anomalocaris ("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 (Unknown if it's phylum was Arthropod). Other Lobopods includes Hallucigenia, Opabinia, and Aysheaia. Other Carnivores of the Burgess Shale include Priapulids (Stem-Group), Hurdia, Peytoia, and Opabinia. Anomalocaris lived with Hallucigenia and Wiwaxia and they both first lived in Chengjiang.
Description[]
Anomalocaris was originally thought to have been a predator before new evidence found it likely feed on either mush or small soft bodied animals. 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", maximizing 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 through 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. Originally it was believed 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. They are the biggest animals of the Burgess Shale and bigger than other Early and Middle Cambrian animals.
Discovery[]
Anomalocaris has been misidentified several times, in part due to its makeup of a mixture of mineralized and unmineralized body parts; the mouth and feeding appendage was considerably harder and more easily fossilized than the delicate body. Its name originates from a description of a detached 'arm', described by Joseph Frederick Whiteaves in 1892 as a separate crustacean-like creature due to its resemblance to the tail of a lobster or shrimp. The first fossilized anomalocarid mouth was discovered by Charles Doolittle Walcott, who mistook it for a jellyfish and placed it in the genus Peytoia. Walcott also discovered a second feeding appendage but failed to realize the similarities to Whiteaves' discovery and instead identified it as feeding appendage or tail of the extinct Sidneyia.[9] The body was discovered separately and classified as a sponge in the genus Laggania; a mouth was found with the body, but was interpreted by its discoverer Simon Conway Morris as an unrelated Peytoia that had through happenstance settled and been preserved with Laggania. Later, while clearing what he thought was an unrelated specimen, Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a shrimp tail and mouth thought to be a jellyfish. Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and feeding appendage actually represented a single, enormous creature.[9] Because Peytoia was named first, it became the correct name for the entire animal. The original feeding arm, however, came from a larger species distinct from Peytoia and "Laggania", which retains the name Anomalocaris.
Stephen Jay Gould cites Anomalocaris as one of the fossilized extinct species he believed to be evidence of a much more diverse set of phyla that existed in the Cambrian period (discussed in his book Wonderful Life), a conclusion disputed by other paleontologists.
In 2011, six fossils of compound eyes dated to the Cambrian period (515 million years ago) were recovered from an archaeological dig at Emu Bay on Kangaroo Island, Australia. The eyes were the first found that belonged to Anomalocaris, proving that Anomalocaris was indeed an arthropod as had been suspected. The find also indicated that advanced arthropod eyes able to "tell friend or foe and detect features of the environment" had evolved very early, before the evolution of jointed legs or hardened exoskeletons. The eyes were 30 times more powerful than those of trilobites, long thought to have had the most advanced eyes of any contemporary species. With 30,000 lenses, the resolution of the 3 centimetres (1.2 in) wide eyes would have been rivalled only by that of the modern dragonfly, which has 28,000 lenses in each eye.
Ecology[]
In the Media[]
Anomalocaris was in the documentary Walking with Monsters, which is made from the same creators of Walking with Dinosaurs. In this documentary, it takes us back in time to the Cambrian when this fearsome predator ruled, and it shows us how it hunted an lived.