| Eryma | |
|---|---|
 | |
| Eryma mandelslohi specimen on display at the State Museum of Natural History Stuttgart | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Family: | † Erymidae |
| Genus: | † Eryma von Meyer, 1840 |
Eryma is a genus of fossil lobster-like crustaceans, containing 44 species. [1]
The Decapoda or decapods are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns, and shrimp. Most decapods are scavengers. The order is estimated to contain nearly 15,000 species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossil decapod is the Devonian Palaeopalaemon.
Pleocyemata is a suborder of decapod crustaceans, erected by Martin Burkenroad in 1963. Burkenroad's classification replaced the earlier sub-orders of Natantia and Reptantia with the monophyletic groups Dendrobranchiata (prawns) and Pleocyemata. Pleocyemata contains all the members of the Reptantia, as well as the Stenopodidea, and Caridea, which contains the true shrimp.
The Achelata is an infra-order of the decapod crustaceans, holding the spiny lobsters, slipper lobsters and their fossil relatives.
The Glypheoidea, is a group of lobster-like decapod crustaceans which forms an important part of fossil faunas, such as the Solnhofen limestone. These fossils included taxa such as Glyphea, and Mecochirus, mostly with elongated chelipeds. This group of decapods is a good example of a living fossil, or a lazarus taxon, since until their discovery in the 1970s, the group was considered to have become extinct in the Eocene. The superfamily Glypheoidea comprises five families. The two extant species, Neoglyphea inopinata and Laurentaeglyphea neocaledonica, are both in the Glypheidae.
Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill, Amphionides and Angustidontida. They are characterised by having the carapace fused to all thoracic segments, and by the possession of stalked eyes.
Glypheidea is an infra-order of decapod crustaceans, comprising a number of fossil forms and the two extant genera Neoglyphea and Laurentaeglyphea:
Calappoidea is a superfamily of crabs comprising the two families Calappidae and Matutidae. The earliest fossils attributable to the Calappoidea date from the Aptian.
Dorippoidea is a superfamily of crabs. The earliest fossils attributable to the Dorippoidea date from the Late Cretaceous.
Calappidae is a family of crabs containing 16 genera, of which 7 are only known as fossils:
Hippoidea is a superfamily of decapod crustaceans known as sand crabs, mole crabs, sand bugs, or sand fleas.
An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. They are distinguished by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. In order to keep growing, they have to go through moulting, which sheds their skin. Arthropods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings. They are an extremely diverse group, with up to 10 million species.
Carpilioidea is a superfamily of crabs containing a single extant family, Carpiliidae and three extinct families. The modern range of the family includes the Indo-Pacific, Western Atlantic and Caribbean Sea. The fossil record of the group extends back at least as far as the Paleocene.
Eubrachyura is a group of decapod crustaceans comprising the more derived crabs. It is divided into two subsections, based on the position of the genital openings in the two sexes. In the Heterotremata, the openings are on the legs in the males, but on the sternum in females, while in the Thoracotremata, the openings are on the sternum in both sexes. This contrasts with the situation in other decapods, in which the genital openings are always on the legs. Heterotremata is the larger of the two groups, containing the species-rich superfamilies Xanthoidea and Pilumnoidea and all the freshwater crabs (Gecarcinucoidea, Potamoidea. The eubrachyura is well known for actively and constantly building its own burrows. The fossil record of the Eubrachyura extends back to the Cretaceous; the supposed Bathonian representative of the group, Hebertides jurassica, ultimately turned out to be Cenozoic in age.
Erymidae is a family of decapod crustaceans known only from fossils. They survived for 100 million years, from the Permo-Triassic boundary to the Hauterivian. Eleven genera are recognised:
Cheiragonidae is a small family of crabs, sometimes called helmet crabs, placed in its own superfamily, Cheriagonoidea. It comprises three extant species, Erimacrus isenbeckii, Telmessus acutidens and Telmessus cheiragonus, there are no yet evidences of Cheiragonidae in the fossil record. Many of these crabs were formerly treated as members of the Atelecyclidae.
Goneplacoidea is a superfamily of crabs containing 11 extant families, and two families known only from fossils.
Antrimpos is an extinct genus of crustacean which existed during the Triassic and Jurassic periods. It contains 15 species, including Antrimpos speciosus.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
Hepatus is a genus of crabs in the family Aethridae, containing seven extant species, plus some fossil species:
Crustaceans form a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, shrimps, prawns, krill, woodlice, and barnacles. The crustacean group can be treated as a subphylum under the clade Mandibulata; because of recent molecular studies it is now well accepted that the crustacean group is paraphyletic, and comprises all animals in the clade Pancrustacea other than hexapods. Some crustaceans are more closely related to insects and the other hexapods than they are to certain other crustaceans.
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