Organism · Molluscs
Stenotheca drepanoida
Fossil record age bounds · ≈ 521–512 Ma
Inferred life reconstruction
Stenotheca drepanoida
Overview
Stenotheca drepanoida was a Cambrian mollusk known from a laterally flattened shell with a strongly curved tip. The curve of its small shell and narrow opening reveal its distinctive form.[1]
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Key facts
Internal molds, formed by rock filling the shell’s inner space, sometimes preserve fine polygonal patterns. Some specimens also show faint lines parallel to the aperture margin, making tiny surfaces a source of research clues.[1]
Time and place
It is studied from Cambrian Series 2 material of the Xinji Formation. Specimens have been described from the Caijiawa and Shangzhangwan sections in present-day Shaanxi Province and the Sanjianfang section in Henan Province, China.[1]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
The shell appears strongly compressed laterally, with a very narrow, elongated aperture. The surface beneath the apex is concave, while the opposite side curves outward, producing an outline of two contrasting curves.[1]
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Habitat and reproduction
The Xinji Formation consists mainly of clastic sediments interbedded with carbonate layers. The study recorded abundant and diverse skeletal fossils in these carbonate layers. The rocks containing tiny shells also offer clues to ancient life.[1]
Fossil discovery
A study published online in 2019 examined at least 4,500 mollusk specimens collected from three sections in northern China. Among them, Stenotheca specimens provide material for comparing small shells from several sections.[1]
References
Research questions
This species appeared in 1984 literature as Anabarella drepanoida and was later reclassified as Stenotheca. Even similar shells reveal different stories when aperture width and curvature are compared.[1]
Observation
The illustration is arranged to guide your gaze along the shell’s form. Move from the backward-curved tip to the narrow, elongated opening and look for the contrasting curves on either side.[1]
Related organisms
Latouchella costataMolluscsFossil record age bounds · ≈ 531–507 MaDifferent curves in small Cambrian shells
Stenotheca and Latouchella are early Cambrian mollusks studied in different regions. Read the flattened, strongly curved shells from present-day China alongside the small, ribbed shells from Britain to find differences in curvature and surface form.