Trigonoida
Classification
Phylum: Mollusca
Class: Bivalvia
Order: Trigonoida Dall, 1889
Cincinnatian Families: Lyrodesmatidae
Geologic Range
?Middle Ordovician, Devonian – Recent
Common Paleoecology
Trigonioda is an extant order or facultatively mobile infaunal suspension feeders
Characteristics of the Order
- Shell trigonal, ovate, or rhomboidal in shape
- Surface smooth or ornamented
- Hinge teeth radiating from the beak; left valve with strong median tooth & right valve typically with two main teeth
- Small adductor scars found close to hinge teeth
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Treatise on Invertebrate Paleontology, Part N, Mollusca 6(1 of 3) (1969):
Treatise on Invertebrate Paleontology, Part N, Mollusca 6(1 of 3) (1969):
- (Characters of superfamily Trigoniacea) Shell equivalve; trigonal, ovate or rhomboidal; posteriorly truncate or subtruncate; posterior slope carinate or subcarinate; surface smooth or ornamented; ligament external, short, opisthodetic. Hinge teeth radiating from beak; left valve typically with strong median tooth and weaker one on each side; right valve typically with two main teeth received in recesses between those of left; additional and weaker teeth may be present, however, or some of teeth mentioned may be obsolete; adductor scars small, placed close to hinge teeth, anterior scar in each valve bordered on its inner side in many forms by buttress may border posterior adductor scar; pallial line entire except in Scaphellinidae; ostracum nacreous.
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Lyrodesmatidae
