It is one of three Praenuculinae genera known solely from Late Ordivician, Caradoc epoch, fossils found in South America.

[1] 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 presence of an auricle, a finger-like projection on the underside of the umbo, in Palaeoconcha also distinguishes specimens from Trigonoconcha.

When described, the genus name Trigonoconcha was chosen by Sánchez in reference to the triangle created by the anterior and posterior margins of the shell.

[1] Similarly, the species epithet acuta was coined as a reference to the acute angle formed by the anterior and posterior margins.