Sp. is an abbreviation for species. Sp. is often used when the genus is known, but the species is not. For example, Tyrannosaurus sp. means a Tyrannosaurus fossil of an undetermined species; it is not known whether it is T. rex , T. bataar, T. efremovi, or a new Tyrannosaurus species. 
Type: Abbreviation Definitions: 1. Abbreviation for species; pl. form is spp.
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