Pseudoniscidae is an extinct

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

synziphosurine Synziphosurina is a paraphyletic group of chelicerate arthropods previously thought to be basal horseshoe crabs (Xiphosura). It was later identified as a grade composed of various basal euchelicerates, eventually excluded form the monophyletic Xi ...

chelicerates The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It contains the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mit ...

that lived in the

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

. Pseudoniscidae is classified inside the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Planaterga Planaterga is a clade of prosomapod euchelicerates including several synziphosurid genera (mainly bunodids and pseudoniscids) and the group Dekatriata (which in turn includes arachnids, chasmataspidids and eurypterid Eurypterids, often ...

, alongside

Bunodidae Bunodidae is an extinct family of synziphosurine chelicerates that lived in the Silurian. Bunodidae is classified inside the clade Planaterga alongside Pseudoniscidae and Dekatriata ( chasmataspidids, eurypterids and arachnids). Bunodidae is com ...

and

Dekatriata Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest ...

( chasmataspidids,

eurypterids Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is l ...

and

arachnids Arachnida () is a Class (biology), class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, came ...

). Pseudoniscidae is composed by two

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, ''

Cyamocephalus ''Cyamocephalus'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Cyamocephalus'' was regarded as part of the clade Planaterga. Fossils of the single and type species, ''C. loganensis'', have been discovered ...

'' and ''

Pseudoniscus ''Pseudoniscus'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Pseudoniscus'' was regarded as part of the clade Planaterga. Fossils of the genus have been discovered in Deposition (geology), deposits of th ...

'' (the type genus).

References

Synziphosurina Planaterga Silurian first appearances Silurian arthropods Silurian extinctions Prehistoric arthropod families {{Chelicerata-stub