Trigonoconcha
genus of molluscs (fossil)
Trigonoconcha is an extinct genus of bivalve in the extinct family Praenuculidae. The genus is one of eleven genera in the subfamily Praenuculinae. It is one of three Praenuculinae genera known solely from Late Ordivician, Caradoc epoch, fossils found in South America. Trigonoconcha currently contains a single accepted species, Trigonoconcha acuta.
Description
Trigonoconcha acuta was first described in 1999 by Teresa M. Sánchez from fossils from sediments of the late Middle Ordivician, Caradocian aged Don Braulio Formation. The formation outcrops on the flank of Sierra de Villicum in the Argentina precordillera.
The shells of Trigonoconcha have anterior and posterior sides which meet at an angle of no more than sixty-five degrees. While this is similar to the related genera Palaeoconcha and Similodonta, they are both noted for anterior-posterior angles of no less than ninety degrees. The presence of an auricle, a finger-like projection on the underside of the umbo, in Palaeoconcha also distinguishes specimens from Trigonoconcha. Similodonta is distinguished from both other genera by an edentulous space, a region on the hinge that lacks teeth.
“Trigonoconcha” enters the record as genus of molluscs (fossil). Crown Archives preserves that source wording while asking what Trigonoconcha, genus and molluscs can confirm, complicate or overturn.
Why this record matters
“Trigonoconcha” is worth following because a concise public description often conceals a longer documentary argument. Here, Trigonoconcha, genus and molluscs provides the most credible route into that argument.
The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Mar 30, 2025. The linked authority identifier is Q7841816. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1999.
A general summary may omit uncertainty, sample limits or methodological disagreement that is explicit in the technical record. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Trigonoconcha” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.