6-823: Chelediscus Rushton, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida Salter (1864). The Treatise assigns this genus to the Calodiscidae; Cotton and Fortey (2005) however move it to the Weymouthiidae. Chelediscus lived during the later part of the Botomian stage . . Chelediscus is known from upper lower Cambrian strata in England, Newfoundland, New York State and Russia (Rushton, 1966; Fletcher, 2003; Rasetti, 1967; Jell in Kaesler, 1997; C. acifer
12-705: Is also recorded from a Limestone at the top of the Torneträsk Formation, probably Ornamentaspis ? linnarssoni Assemblage Zone, in the Luobakti section, south of Lake Torneträsk, northern Swedish Lapland and the lower to middle Brigus Formation ( Hupeolenus Zone; Tannudiscus balanus Subzone) at Cape St Mary's, Newfoundland (Fletcher, 2003). This Agnostida -related article is a stub . You can help Misplaced Pages by expanding it . Weymouthiidae The Weymouthiidae are an extinct family of eodiscinid agnostid trilobites . They lived during
18-758: Is large for the Eodiscina. The glabella is wide at its base, normally parallel sided but may taper gently or be at its widest at half length. Glabellar furrows are mainly absent, but incomplete furrows may be present in some species and deeply impressed transglabellar furrows also occur. Free cheeks (or fixigenae) are normally confluent in front of glabella. The occipital ring may be simple or split into two lateral lobes (e. g. in Chelediscus and Tannudiscus ). All Weymouthiidae lack eyes. The thorax consists of three rings when known ( Mallagnostus , Marocconus , Serrodiscus , Tannudiscus and Weymouthia ). The pygidial axis
24-477: Is long and strongly tapered with 10 or more axial rings. The segmentation of the axis, however, is often effaced. The Weymouthiidae include forms with the rear of the glabella roundly expanded over the occipital ring or with a vertical spine, forms in which the occipital ring cannot be discerned because the glabella is expanded, and forms with a primitive occipital structure but with a greatly increased numbers of axial segments. This Agnostida -related article
30-470: Is nested within it, particularly in the clade that further consists of the genera Mallagnostus , Chelediscus , Tannudiscus and Jinghediscus . The trend in the Weymouthiidae to reduce the occipital ring is carried furthest in Chelediscus , Tannudiscus and the Agnostina with the occipital ring divided into basal lobes. Most taxa in this family are small (1–2 cm or 0.4–0.8 inches long), but this
36-534: The late Lower Cambrian and earliest Middle Cambrian (Botomian to Delamaran) in the so-called Olenellus - and Eokochaspis -zones in the former paleocontinents of Laurentia , Avalonia , Gondwana . The Weymouthiidae are all blind and lack free cheeks. The Weymouthiidae have developed from a stock within the Hebediscidae . The Weymouthiidae are a paraphyletic family because the Agnostina suborder
#205794