Cancrinos is a genus of fossil crustaceans closely allied with the slipper lobsters. One species is known, C. claviger from the Jurassic of southern Germany.
Cancrinos Temporal range:
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Decapoda |
Suborder: | Pleocyemata |
Family: | †Cancrinidae |
Genus: | †Cancrinos Münster, 1839 |
Species: | †C. claviger
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Binomial name | |
†Cancrinos claviger Münster, 1839
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Fossils of Cancrinos are rare, and their state of preservation is often imperfect.[1] Count Georg zu Münster first described Cancrinos in 1839, based on material from the Upper Jurassic Solnhofen limestones of southern Germany.[2] He described two species, Cancrinos claviger and C. latipes, differentiated by the size of the second antennae,[2] but the two are now considered to be synonyms.[1]
Further specimens have been discovered in Upper Cretaceous lithographic limestones of Lebanon, and described as a new species, C. libanensis;[3] however, Haug et al. (2016) made it the type species of a separate genus Paracancrinos.[4]
Although Münster was unable to discern any living relatives of Cancrinos during his original description,[2] Reinhard Förster proposed in 1984 that Cancrinos was a transitional form between spiny lobsters (Palinuridae) and slipper lobsters (Scyllaridae).[5][6]
Cancrinos differs most markedly from other related animals by the form of the second antennae, which are flattened towards the end, approaching the state seen in living slipper lobsters.[7] Unlike living slipper lobsters, however, the flattened, distal parts of the antennae retain the ancestral state of comprising many segments, rather than being reduced to a single element.[7]
Because immature specimens have been found, parts of the ontogeny of Cancrinos are known, although it is unclear whether the smallest specimens are in the puerulus stage, or are juveniles.[1] Younger specimens have less flattened antennae, more like those of living spiny lobsters; thus, Canrcinos exhibits a form of heterochrony known as peramorphosis.[7] This ontogeny is thought to reflect the phylogeny of Cancrinos, representing a partial development from the ancestral spiny lobster-like form towards the derived slipper lobster-like form.[7]