Agnostida

Agnostida
Temporal range: Cambrian Stage 3 –Late Ordovician
Itagnostus interstrictus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
(unranked): Artiopoda
Subphylum: Trilobitomorpha
Class: Trilobita (?)
Order: Agnostida
Salter, 1864
Families

Suborder Agnostina

Suborder Eodiscina

Synonyms

Isopygia Gürich, 1907
Miomera Jækel, 1909

Agnostida are an order of extinct arthropods which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda.[1] They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician.[2]

  1. ^ Moysiuk J, Caron JB (January 2019). "Burgess Shale fossils shed light on the agnostid problem". Proceedings. Biological Sciences. 286 (1894): 20182314. doi:10.1098/rspb.2018.2314. PMC 6367181. PMID 30963877.
  2. ^ Barnes BD, Sclafani JA, Zaffos A (April 2021). "Dead clades walking are a pervasive macroevolutionary pattern". Proceedings of the National Academy of Sciences of the United States of America. 118 (15). doi:10.1073/pnas.2019208118. PMC 8053996. PMID 33827921. S2CID 233184869.