Ptychagnostidae

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: †Trilobitomorpha
Classis: †Trilobita
Ordo: †Agnostida
Subordo: †Agnostina
Superfamilia: †Agnostoidea

Familia: Ptychagnostidae
Genera: Allobodochus – Criotypus – Goniagnostus – Lejopyge – Myrmecomimus – Onymagnostus – Ptychagnostus – Schismagnostus – Tomagnostella – Tomagnostus – Yakutiana
Name
Ptychagnostidae Kobayashi 1939

Ptychagnostidae is a family of agnostid trilobites from the 5th Stage to the Paibian Age of the Cambrian (509 to 497 million years ago).[1] The family includes several important index fossils.
Description

Like all agnostids, ptychagnostids have cephalons and pygidia that are more or less uniform in size and shape (isopygous). The thorax is composed of two body segments (somites). They are completely blind.[2]
Distribution and age range

Ptychagnostidae has a cosmopolitan distribution. They existed during the 5th Stage of the Series 3 Epoch to the Paibian Age of the early Furongian Epoch in the Cambrian (509 to 497 million years ago).[1] The earliest member of the family is Ptychagnostus praecurrens from the Burgess Shale fauna.[3]
Taxonomy

Ptychagnostidae is classified under the superfamily Agnostoidea of the suborder Agnostina, order Agnostida. The family was first established by the Japanese paleontologist Teiichi Kobayashi in 1939. Its name comes from the type genus, Ptychagnostus. It includes the following genera (with their taxonomic synonyms):[2]

Allobodochus Opik, 1979
Criotypus Opik, 1979
Goniagnostus Howell, 1935
Lejopyge Hawle & Corda, 1847

= Miagnostus

Myrmecomimus Opik, 1979
Onymagnostus Opik, 1979

= Agnostonymus

Pseudophalacroma Pokrovskaya, 1958
Ptychagnostus Jaekel, 1909

=Triplagnostus, Huarpagnostus, Solenagnostus, Pentagnostus, Aristarius, Aotagnostus, Acidusus, Canotagnostus, Zeteagnostus

Schismagnostus Robison, 1994
Tomagnostella Kobayashi, 1939a
Tomagnostus Howell, 1935
Yakutiana Özdikmen, 2009

References

"Ptychagnostidae". Paleobiology Database. Retrieved 18 November 2012.
Samuel M. Gon III. "Agnostida Fact Sheet". A Guide to the Orders of Trilobites. Retrieved 18 November 2012.
Richard A. Robison (1984). "Cambrian trilobites of east-central Alaska". Cambrian Agnostida of North America and Greenland: Part I: Ptychagnostidae. The University of Kansas Paleontological Contributions: Paper 109. Paleontological Institute, University of Kansas. pp. 1–60. ISSN 0075-5052.