Latin: doubtful name.
In paleontology and zoology, a term which means that a classification is dubious, pending additional discoveries, because there is not enough fossil material to define a new species. Thus, the name given to the genus or species is not official.
Especially with a single incomplete specimen, it may be premature to declare a new species has been found. Variations in bone structure that are discovered in an individual specimen may be indicative of a diseased or distressed individual, juvenile features, or even irregularities in fossilization.
The term can be applied retroactively to discoveries, if the type specimen is useless for comparison, due to deterioration, incompleteness, or even rushed or substandard research (for example, a tooth used to establish the Trachodon genus was later discovered to belong to a ceratopsian).
Famous nomina dubia:
Jeananda Col. "Paleontology and Geology Glossary." Enchanted Learning. 1996. <http://www.enchantedlearning.com/subjects/dinosaurs/glossary/indexn.shtml> (10 June 2004)
T. Mike Keesey. "Stegosaurus." The Dinosauricon. 2001. <http://dinosauricon.com/genera/stegosaurus.html> (10 June 2004)
---. "Tyrannosaurus." The Dinosauricon. 2001. <http://dinosauricon.com/genera/tyrannosaurus.html> (10 June 2004)
George Olshevsky. "Whatever happened to Trachodon?" Dinosauria.com 11 August 1997. <http://www.dinosauria.com/jdp/misc/trachodon.html> (10 June 2004)
"How Do Dinosaurs Get Their Names?" Walking with Dinosaurs - Discovery Channel. 2000. <http://dsc.discovery.com/stories/dinos/bbc/howdoweknow/q48.html> (10 June 2004)