Stephanosaurus is a dubious

Nomen dubium

In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...

 genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of hadrosaurid dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

, with a complicated taxonomic

Taxonomy

Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

 history.

In 1902, Lawrence Lambe

Lawrence Lambe

Lawrence Morris Lambe was a Canadian geologist and palaeontologist from the Geological Survey of Canada .His published work, describing the diverse and plentiful dinosaur discoveries from the fossil beds in Alberta, did much to bring dinosaurs into the public eye and helped usher in the Golden...

 named a new set of hadrosaurid limb material and other bones (originally GSC 419) from Alberta as Trachodon marginatus

Trachodon

Trachodon is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.A...

. Paleontologists began finding better remains of hadrosaurids from the same rocks in the 1910s, in what is now known as the late Campanian

Campanian

The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

-age (Upper Cretaceous) Dinosaur Park Formation

Dinosaur Park Formation

The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...

. Lambe assigned two new skulls to T. marginatus, and based on the new information, coined the genus Stephanosaurus for the species in 1914. Lambe retained the original species marginatus, so the type specimen of Stephanosaurus was the original, scrappy limb bones and crushed skull fragments, not the two new skulls. However, the limb bones and skull fragments could not be reliably said to come from the same animal as the complete skulls, or differentiated from other hadrosaurs. Because there was very little to associate the complete skulls with the scrappy earlier marginatus material, in 1923 William Parks proposed a new genus and species for the skulls, with both generic and specific names honoring Lambe: Lambeosaurus lambei

Lambeosaurus

Lambeosaurus is a genus of hadrosaurid dinosaur that lived about 76 to 75 million years ago, in the Late Cretaceous Period of North America. This bipedal/quadrupedal, herbivorous dinosaur is known for its distinctive hollow cranial crest, which in the best-known species resembled a hatchet...

(type specimen

Biological type

In biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...

 NMC

Canadian Museum of Nature

The Canadian Museum of Nature is a natural history museum in Ottawa, Ontario, Canada. Its collections, which were started by the Geological Survey of Canada in 1856, include all aspects of the intersection of human society and nature, from gardening to gene-splicing...

2869, originally GSC 2869).