Strabopidae

{{Taxobox

| name = Strabopidae

| fossil_range = {{fossil range|Cambrian}}

| image = Strabops thatcheri fossil aglaspidid. Potosi Dolomite, Upper Cambrian.jpg

| image_caption = Fossil of Strabops thacheri.

| regnum = Animalia

| phylum = Arthropoda

| unranked_subphylum = Arachnomorpha

| ordo = †Strabopida

| ordo_authority = Hou & Bergström, 1997

| familia = †Strabopidae

| familia_authority = Gerhardt, 1932

| type_species = †Strabops thacheri

| type_species_authority = Beecher, 1901

| subdivision_ranks = Genera

| subdivision = * †Khankaspis?

• †Paleomerus
• †Parapaleomerus
• †Strabops

| synonyms =

}}

Strabopidae is the only family of the order Strabopida, an extinct group of arthropods known from the Cambrian period.

The order Strabopida contains three valid genera and one doubtful, Khankaspis, Paleomerus, Parapaleomerus and Strabops, all assigned in the family Strabopidae.{{cite journal|title=Trilobite and xiphosuran affinities for putative aglaspidid arthropods Caryon and Drabovaspis, Upper Ordovician, Czech Republic|author=Javier Ortega-Hernández|author2=Simon J. Braddy|author3=Štěpán Rak|journal=Lethaia|date=9 March 2010|volume=43|issue=3|pages=427–431|doi=10.1111/j.1502-3931.2010.00216.x|bibcode=2010Letha..43..427O }} Previously, it also contained the genera Caryon, Lemoneites and Neostrabops, but after a study, they were reassigned as a trilobite, a glyptocystitid echinoderm and a cheloniellid arthropod, respectively.

Paleomeridae was also previously included as a family, but after the discovery of a fourth Paleomerus specimen and its study, Paleomeridae was synonymized into Strabopidae.{{cite journal|title=A new specimen of Paleomerus hamiltoni (Arthropoda; Arachnomorpha)|author=O. Erik Tetlie|author2=Rachel A. Moore|journal=Transactions of the Royal Society of Edinburgh: Earth Sciences|volume=94|issue=3|pages=195–198|year=2004|doi=10.1017/S0263593300000602|citeseerx = 10.1.1.717.1248|s2cid=129086749}} Although often suggested to be closely related to aglaspidids due to their similar morphology, their exact phylogenetic placement is uncertain due to the poor preservation of all known strabopids. A 2013 attempt to place them in a phylogenetic analysis recovered them as part of a polytomy with megacheirans, marrellomorphs, crustaceans and artiopodans.{{Cite journal |last1=Ortega-Hernández |first1=Javier |last2=Legg |first2=David A. |last3=Braddy |first3=Simon J. |date=February 2013 |title=The phylogeny of aglaspidid arthropods and the internal relationships within Artiopoda |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1096-0031.2012.00413.x |journal=Cladistics |language=en |volume=29 |issue=1 |pages=15–45 |doi=10.1111/j.1096-0031.2012.00413.x|pmid=34814371 }} Still, strabopids are often classified as part of the clade Arachnomorpha. In fact, Dunlop & Selden (1998) defined Paleomerus as "perhaps the best model of a primitive arachnomorph".{{cite book|title=Arthropod Relationships|chapter=The early history and phylogeny of the chelicerates|last1=Dunlop|first1=J. A.|last2=Selden|first2=Paul A.|year=1998|journal=Arthropod Relationships. The Systematics Association Special Volume Series|volume=55|page=229|doi=10.1007/978-94-011-4904-4_17|isbn = 978-94-010-6057-8}}