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Trigonoconcha acuta

Bivalvia - Nuculida - Praenuculidae

Trigonoconcha acuta was named by Sanchez (1999). Its type specimen is CEGH-UNC 16158, a shell (One internal mold of left valve), and it is a 3D body fossil. Its type locality is south side of the Quebrada La Pola, Eastern flank of Sierra de Villicum, which is in a Caradoc marine conglomerate in the La Cantera Formation of Argentina. It is the type species of Trigonoconcha.

Synonymy list
YearName and author
1999Trigonoconcha acuta Sanchez figs. 2.9-2.13, 5.1-5.2

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EubilateriaAx 1987
subclassProtobranchia(Pelseneer 1889)
superorderNuculiformiiDall 1889
orderNuculida(Dall 1889)
superfamilyNuculoidea(Gray 1824)
familyPraenuculidaeMcAlester 1968
subfamilyPraenuculinaeMcAlister 1969

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Trigonoconcha acuta Sanchez 1999
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T. M. Sanchez 1999Orientation follows suggestions by Bradshaw and Bradshaw (1971), who consider the row with the bigger teeth as anterior. Equilateral, dorsoventrally elongated shells with triangular dorsal outline and rounded ventral outline; anteroventral region expanded, posteroventral region reduced; anterior and posterior dorsal margins meeting with angle up to 65 degrees; subcentral umbo, orthogyrate to opisthogyrate; dorsal region opisthocline due to position of anteroposterior axis as suggested by Stanley (1970) (Fig. 5.1); anterior, posterior, and ventral margins forming broad, anteriorly expanded curve; in some small shells (younger growth stages?) anterior and posterior margins curving abruptly, meeting with horizontal ventral margin, resulting in triangular shell outline (Figs. 2.12, 5.2); chevroned, convexodont teeth; up to 15 anterior teeth, up to 10 posterior teeth; anterior teeth larger than posterior teeth, both meeting by three or four small orthomorphic elements (Fig. 5.1); tooth development similar in both smaller and bigger shells; anterior adductor muscle scar well marked, rounded, placed below distal hinge extremity; weak, ovate posterior adductor muscle scar; pallial line entire; ornamentation not preserved.
valve height64.822.507.005.551.73

Composition: aragonitec
Locomotion: facultatively mobilef
Attached: yesf
Life habit: shallow infaunalf
Diet: deposit feederf
Vision: blindc
Created: 2009-07-20 12:59:23
Modified: 2009-10-10 17:23:16
Source: f = family, c = class
References: Meyer et al. 2009, Aberhan et al. 2004

Age range: Caradoc or 458.40000 to 449.50000 Ma

Collections: one only

Time interval Ma Country or state Original ID and collection number
Caradoc458.4 - 449.5Argentina (San Juan) Trigonoconcha acuta (type locality: 13513)