Sagavia
From Kazakhstan Encyclopedia
Template:Italic title Template:Taxobox Sagavia is a genus of trilobites that lived during the Middle and Upper Ordovician in what are now Northwest and Southeast China, North Kazakhstan and Wales. It is a typical cyclopygid that can be distinguished by its large but separate eyes, elongated glabella, five thorax segments and a pygidium with clearly defined axis and border.[1]
Distribution
- S. felix has been collected from the Middle Ordovician of Kazakhstan (Caradoc, Nemagraptus gracilis Zone, Saga Formation, Saga River section, Stepnyak district).
- S. modica is known from the Middle Ordovician of Kazakhstan (Caradoc, Nemagraptus gracilis Zone, Saga Formation, Saga River section, Stepnyak district).
- S. chuanxiensis was found in the Middle and Upper Ordovician of China (late Caradoc-Ashgill, top of the Pagoda Formation, limestone block in a Triassic melange accumulation at Shiqu; Yuanba, Hougou and Liangshan, Nanzheng; Dangmengou and Zhuyegou, Ningqiang; Qishuba and Gaoqiaogou, Mianxian; all Northwestern Sichuan).
- S. zhuyegouensis occurs at the Middle Ordovician of China (late Caradoc, Dangmengou, Ningqiang Northwestern Sichuan).
- S. elongata is present in the Upper Ordovician of China (?Ashgill, Kielanella-Tretaspis Beds of the Ulugtay District, south Tien Shan).
- S. glans was excavated from the Upper Ordovician of the United Kingdom (late Arenig, Pontyfenni Formation, South Wales).
- S. heterocyclopygeformis is known from the Middle Ordovician of northern Kazakhstan (Caradoc).
- S. novakellaformis occurs at the Koroleva from the Middle Ordovician of northern Kazakhstan (late Llanvirn?), and the United Kingdom (Hustedograptus teretiusculus Biozone of the Llanfawn Mudstone Formation, central Wales).[1]
Description
The glabella of Sagavia is elongate with parallel sides or slightly converging towards the front. The large eyes are separated at the front by the glabella and the cephalic doublure. The rostral suture is vaulted upwards. It has a thorax of five segments. Sagavia has a pygidium with well a defined axis and border with clear furrows.[1]
- Sagavia is similar to Microparia but has a more elongate glabella and much better defined pygidial axis and border.
- Heterocyclopyge also has a defined pygidial axis, a five-segmented thorax, and a defined pygidial border, but has a shorter glabella and the pygidial border and axis are poorly defined medially.[1]
References
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