| Aengapentastomum Temporal range: | |
|---|---|
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| A reconstruction of Aengapentastomum | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Ichthyostraca |
| Subclass: | Pentastomida |
| Genus: | † Aengapentastomum Waloszek, Repetski & Maas, 2005 |
| Species: | †A. andresi |
| Binomial name | |
| †Aengapentastomum andresi Waloszek, Repetski & Maas, 2005 | |
Aengapentastomum is a Cambrian genus of pentastomid from the Orsten of Sweden, [1] containing one species, Aengapentastomum andresi.
Aengapentastomum is roughly 730 micrometers long from head to tail. Unlike other Cambrian pentastomids, it lacks vestigial trunk limbs, therefore it is likely closer to the crown-group. It has two pairs of head limbs, both smooth and rounded, with inward-facing podomeres. A swelling of unknown function, likely akin to the "dorsal organs" of modern pentastomid larvae, occurs roughly half-way down the length of the body. The tail has a rounded end, with two structures at its tip. The head is subtriangular, with no head shield, despite a furrow around the appendages and a prominent margin giving the effect of one at some angles. The trunk is unsegmented, with seemingly no annulations either. Aengapentastomum is known from one complete specimen, with an earlier described larva also resembling it, however this larva is much smaller and only has one pair of appendages, therefore it is likely either an earlier developmental stage or a close relative. This genus, alongside other Orsten pentastomids, is likely a larval form with the adults not being preserved. [1]
Aengapentastomum derives from the Änga quarry where it was found, alongside the fact it is a pentastomid. The species name andresi honours Dietmar Andres, who first described pentastomid fossils from the Orsten. [1]
Yohoia is an extinct genus of megacheiran arthropod from the Cambrian period that has been found as fossils in the Burgess Shale formation of British Columbia, Canada. The type species, Yohoia tenuis, was described in 1912 by Walcott, who considered it an anostracan crustacean. 711 specimens of Yohoia are known from the Greater Phyllopod bed, where they comprise 1.35% of the community. In 2015, Conway Morris et al. reported another species, Y. utahana, from the Marjum Formation, Utah.
Anomalocaris is an extinct genus of radiodont, an order of early-diverging stem-group arthropods.
The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus Linguatula to a vertebrate tongue; molecular studies point to them being highly-derived crustaceans.
Fuxianhuia is a genus of Lower Cambrian fossil arthropod known from the Chengjiang fauna in China. Its purportedly primitive features have led to its playing a pivotal role in discussions about the euarthropod stem group. Nevertheless, despite being known from many specimens, disputes about its morphology, in particular its head appendages, have made it one of the most controversial of the Chengjiang taxa, and it has been discussed extensively in the context of the arthropod head problem.
Isoxys is a genus of extinct bivalved Cambrian arthropod; the various species of which are thought to have been freely swimming predators. It had a pair of large spherical eyes, and two large frontal appendages used to grasp prey.
Hadranax is a genus of large lobopodian known from the lower Cambrian Sirius Passet Lagerstätte. This genus is characterized from other lobopodians due to multiple groups of four nodes running along its trunk region, similar to Kerygmachela, and a pair of extremely large frontal appendages that were possibly as long as the animal's entire body. This lobopodian is one of the rarer members of the Sirius Passet fauna, with only around three fragmentary specimens being known.
Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and were used for a variety of functions. Radiodonts were among the earliest large predators, but they also included sediment sifters and filter feeders. Some of the most famous species of radiodonts are the Cambrian taxa Anomalocaris canadensis, Hurdia victoria, Peytoia nathorsti, Titanokorys gainesi, Cambroraster falcatus and Amplectobelua symbrachiata. The later surviving members include the subfamily Aegirocassisinae from the Early Ordovician of Morocco and the Early Devonian member Schinderhannes bartelsi from Germany.
Fengzhengia is an extinct genus of arthropod known from a single species, Fengzhengia mamingae from the Cambrian aged Chengjiang Biota of Yunnan, China. It is thought to be a basal arthropod, as one of the most basal members of Deuteropoda. Like other basal deuteropods, Fengzhengia has an upward curling pair of "frontal appendages" with at least 6 segments which bear endites, contrasting with the downward curving pair of frontal appendages possessed by radiodonts. The head has a pair of stalked eyes. The trunk had 15 tergites the first nine of which had upward facing spines, with the trunk terminating with a tail fan. The trunk seemingly had pairs of biramous limbs, with paddle-shaped exopods. It is thought to have been nektobenthic, and either a scavenger or a predator. A close relationship with the genus Kylinxia has been suggested.
Surusicaris is an extinct genus of bivalved arthropod, known from the Cambrian Burgess Shale of British Columbia, Canada. It is considered to be closely related to Isoxys, and like it has spined grasping frontal appendages.
Phosphatocopina is an extinct group of bivalved arthropods known from the Cambrian period. They are generally sub-milimetric to a few millimetres in size. They are typically only known from isolated carapaces, but some found in Orsten-type phosphatized preservation have their bodies preserved in high fidelity in three dimensions.
Oelandocaris is an extinct genus of stem-mandibulate, or possibly a megacheiran, within the family Oelandocarididae.
Martinssonia is an extinct genus of Cambrian arthropod from the Orsten Lagerstätte.
Musacaris is an extinct genus of Cambrian arthropod from the Orsten Lagerstätte, formerly synonymous with Martinssonia. It contains only a single species, Musacaris gerdgeyeri.
Bredocaris admirabilis is a genus of pancrustacean from the Cambrian Orsten.
Henningsmoenicaris scutula is a Cambrian genus of arthropod from the Orsten of Sweden. It was formerly named Henningsmoenia, however this name was preoccupied by an ostracod, therefore it was renamed. Its genus name translates to "Henningsmoen's shrimp" after G. Henningsmoen. The species name, scutula is in reference to the large, bowl-shaped carapace.
Sandtorpia vestrogothiensis is a Cambrian arthropod from the Orsten of Sweden. It is known from a single specimen.
Boeckelericambria is a Cambrian genus of pentastomid from the Orsten of Sweden, containing one species, Boeckelericambria pelturae.
Haffnericambria is a Cambrian genus of pentastomid from the Orsten of Sweden, containing one species, H. trolmeniensis.
Heymonsicambria is a Cambrian genus of pentastomid from the Orsten of Sweden, containing five species, H. kinnekullensis, H. scandica, H. repetskii, H. taylori and H. gossmannae.
Dietericambria hensoniensis is a Cambrian pentastomid from the Henson Gletscher Formation of Greenland. It is the oldest known pentastomid, being at least 15 million years older than the forms recorded from the Orsten.
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