MULTICRUSTACEA
MULTICRUSTACEA
Origins: 521 million years ago (middle Cambrian period, Stage 3)
Extinction: Still extant
Multicrustaceans are the largest superclass of crustaceans (ignoring the inclusion of insects), containing nearly 80% of all non-insect crustacean species, and are represented, in the modern day, by a myriad of creatures, such as crabs, lobsters, crayfish, shrimp, krill, woodlice, barnacles, copepods, mantis shrimp, etc.
main source: Wikipedia
Phylogeny
- Insecta
- Multicrustacea
- Juracyclus posidoniae
- Uncina posidoniae
NAME: Juracyclus posidoniae
SIZE: 1.8 centimeters long
DESCRIBED BY: Schweigert, 2007
CLOSEST LIVING RELATIVES: Malacostracans (potentially)
DEPICTED IN: The Life of a Temnodontosaurus episode 17
Juracyclus posidoniae is part of the extinct order Cyclida, making it a type of cycloid, a group of crab-like crustaceans dating from the Carboniferous up to the early Jurassic, to which this is the last of its kind.
Some cycloids had gill plates arranged in an horseshoe shape beneath the carapace. The eyes of some cycloids were stalked, and the head beared two pairs of antennae, the first, named the antennulae, being significantly longer than the much smaller second pair. The abdomen was short, with either one or two segments, ending in a pair of posterior segments named caudal rami, which were serrated, and could perhaps serve as protection from attackers.
Despite being a crustacean, Juracyclus affinities, and cycloids as a whole, with other crustaceans have been under debate, for their anatomical features are not very conclusive with a placement. Very early scientific descriptions of cycloids associated them with trilobites. Although soon rejected as being outside of a trilobite affinity, occasionally both types of organisms were confused with each other. Later cycloids were speculated to be related to copepods, others placed them closer to malacostracans (which include crabs, woodlice, krill, etc.).
Juracyclus probably inhabited the sea bottom, either in reefs or very deep marine settings. It was likely a detritivore, or a scavenger, though could also be a predator or a consumer of plant matter, in an ecology that might have been quite similar to that of a crab, which were a very recent development in crustacean evolution, during the early Jurassic. A more sensational hypothesis for cycloid ecology is that they were parasites, but given their significantly large size and calcified exoskeleton, that seems unlikely.
Juracyclus is a holdover from a Paleozoic lineage of early crustaceans that has managed to survive the Permian-Triassic extinction, alongside other emblematic Paleozoic arthropod lineages, like the euthycarcinoids and the thylacocephalans, which became extinct later around the Mesozoic as well. Juracyclus is part of the Halicynidae family, which is recognizable from the middle to late Triassic of Europe, apparently the last geographic refuge of this enigmatic lineage of crustaceans.
NAME: Uncina posidoniae
SIZE: 35-50 centimeters long
DESCRIBED BY: Quenstedt, 1851
CLOSEST LIVING RELATIVES: Reef lobsters
DEPICTED IN: The Life of a Temnodontosaurus episode 2
Uncina posidoniae is an astacidean crustacean, closely related to the modern reef lobsters. It was one of the largest crustaceans of the Jurassic period, reaching lengths of nearly half a meter long. It is also the largest species of the genus Uncina. It was a bottom dwelling creature, hunting a myriad of different prey. With its enormously large claws, it would have hunted all kinds of invertebrates and vertebrates in the early Jurassic seas.