Hebediscidae

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: Eodiscina
Superfamilia: Eodiscoidea

Familia: † Hebediscidae
Genera: †Delgadella – †Dicerodiscus – †Hebediscus – †Limbadiscus – †Luvsanodiscus – †Neopagetina – †Parapagetia – †Tchernyshevioides
Name
Hebediscidae Kobayashi 1944

The Hebediscidae Kobayashi, 1944, are a family of trilobites belonging to the order Agnostida that lived during the Lower Cambrian (Atdabanian to Toyonian). They are small or very small, and have a thorax of two or three segments. The Hebediscidae include five genera (see box).
Taxonomy

The Hebediscidae probably descended from the Tsunydiscidae and gave rise to the Weymouthiidae.[2]
Description

Like all Agnostida, the Hebediscidae are diminutive and the headshield (or cephalon) and tailshield (or pygidium) are of approximately the same size (or isopygous) and outline. In the Hebediscidae, the central raised area of the cephalon (or glabella) is wide at its rear end, has parallel sides or tapers forward, and without transverse glabellar furrows, although the lobes may be apparent if they are expanded. A three segment thorax is known in Hebediscus, Delgadella and Tchernyshevioides. The pygidium has a wide, tapering axis of more than four segments.[1]
References

WHITTINGTON, H. B. (1997). Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. Treatise on Invertebrate Paleontology. Vol. Part O, Revised. pp. 390–392.
JELL, P. A. (1975). "Australian Middle Cambrian Eodiscoids with a review of the superfamily". Palaeontographica Abteilung A. 150: 1–97. cited in WHITTINGTON, H. B. (1997). Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. Treatise on Invertebrate Paleontology. Vol. Part O, Revised. pp. 348–349.