Diaphanometopidae

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: †Phacopida
Subordo: †Phacopina
Superfamilia: Dalmanitoidea

Familia: Diaphanometopidae
Genera (3): Diaphanometopus – Gyrometopus – Prodalmanitina
Name

Diaphanometopidae Jaanusson & Moore, 1959

Diaphanometopidae is a family of trilobites. Its representatives lived during the Arenig and Llanvirn stages of the Ordovician Period, approximately 479 to 463 million years ago.[1] The Diaphanometopidae are thought to have been an early transitional group between the Ptychopariida ancestors and all other Phacopina. Diaphanometopidae, are found in the Lower and Middle Ordovician of Sweden and Russia.[1][2][3] Three species are assigned to this family: Diaphanometopus volborthi that has been found in the Dapingian of Baltica, Gyrometopus lineatus occurring in the Floian of Baltica and Prodalmanitina nikolaevi that is known from the Floian of Kolyma. These species have many ancestral characters compared to other Phacopina, but they do not seem to be each other's nearest relatives, which makes it unlikely this family will be maintained when the phylogeny has been studied in more detail.[4]
References

Moore, R. C. (ed.). Treatise on Invertebrate Paleontology. Part O – Arthropoda (Trilobitomorpha). 1959
"Per Hansson's trilobite gallery - Trilobites from Sweden".
Jell, P. A.; Adrian, J. M. (2002). "Available generic names for trilobites". Memoirs of the Queensland Museum. 48 (part 2): 331–553.
J.M. Adrian (2014). "20. A synopsis of Ordovician trilobite distribution and diversity". In D.A.T. Harper; T. Servais (eds.). Early Palaeozoic Biogeography and Palaeogeography. Memoirs of the Geological Society of London. Vol. 38. Geological Society of London. p. 490. ISBN 978-1862393738.