page_title: Lambeosaurus
section_title: Dodson's two species model to present
hierarchical_section_title: Lambeosaurus / History and species / Dodson's two species model to present
caption_attribution_description: Headshots of Lambeosaurus lambei for what is believed to be different genders and different growth stages. Based on skull drawings by Lull and Wright, 1942. Pencil drawing. For updated versions, see File:Lambeosaurus BW.jpg and File:Lambeosaurus lambei BW (updated).jpg.
context_page_description: Lambeosaurus is a genus of hadrosaurid dinosaur that lived about 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. Several possible species have been named, from Canada, the United States, and Mexico, but only the two Canadian species are currently recognized as valid.
  Material relevant to the genus was first named by Lawrence Lambe in 1902. Over twenty years later, the modern name was coined in 1923 by William Parks, in honour of Lambe, based on better preserved specimens. The genus has a complicated taxonomic history, in part because small-bodied crested hadrosaurids now recognized as juveniles were once thought to belong to their own genera and species. Currently, the various skulls assigned to the type species L. lambei are interpreted as showing age differences and sexual dimorphism. Lambeosaurus was closely related to the better known Corythosaurus, which is found in slightly older rocks, as well as the less well-known genera Hypacrosaurus and Olorotitan.
context_section_description: In 1975, Peter Dodson, examining why there should be so many species and genera of lambeosaurine duckbills within such a short geological time frame and small area, published the results of a morphometric study in which he measured dozens of skulls. He found that many of the species had been based on remains that were better interpreted as juveniles or different sexes, something touched on but largely ignored in older literature. For Lambeosaurus, he found that L. clavinitialis was probably the female of L. lambei, and Corythosaurus frontalis and Procheneosaurus praeceps were probably its juveniles. L. magnicristatus was different enough to warrant its own species. He interpreted Procheneosaurus cranibrevis and P. erectofrons as juvenile corythosaurs. However, restudy of the Procheneosaurus/Tetragonosaurus remains indicates that within species, assignments had become confused, and the type specimen of P. cranibrevis was a Lambeosaurus juvenile, whereas others were Corythosaurus, based on the distinctive form of the contact of the nasal bone with the premaxilla.
  Dodson's model would become widely accepted, and two species of Lambeosaurus are regularly recognized today, with a third sometimes accepted. L. lambei (Parks, 1923) is known from at least 17 individuals, with seven skulls and partial skeletons and around ten isolated skulls. L. clavinitialis (C.M. Sternberg, 1935), Corythosaurus frontalis (Parks, 1935), and Procheneosaurus praeceps (Parks, 1931) are all still regarded as synonyms of L. lambei in recent reviews. Some palaeontologists suggest that L. clavinitialis skulls without the backward spine may represent L. magnicristatus individuals instead,; this was rejected in the 2007 redescription of L. magnicristatus.
  The second species, L. magnicristatus (C.M. Sternberg, 1935) is only definitely known from two specimens, both with skulls. Unfortunately, the majority of the articulated skeleton of the type specimen has been lost. Many of the bones were extensively damaged by water while in storage and were discarded before description; other portions of this skeleton have also been lost. Its remains come from slightly younger rocks than L. lambei. The specific name is derived from the Latin magnus "large" and cristatus "crested", referring to its bony crest. Additionally, Jack Horner has identified fragmentary lambeosaurine jaws from the Bearpaw Formation of Montana as possibly belonging to L. magnicristatus; these represent the first lambeosaurine remains from marine rocks.
  Other less accepted species have been discussed in the 21st century. Lambeosaurus paucidens (named by Marsh 1889 and referred to Lambeosaurus in 1964) is generally regarded as a dubious name and was listed as Hadrosaurus paucidens in a 2004 review, although at least one author, Donald F. Glut, has accepted it as a species of Lambeosaurus. In this case, the specific epithet is derived from the Latin pauci- "few" and dens "tooth". The irregularities of Procheneosaurus cranibrevis, and the identity of the type as a juvenile lambeosaur, were recognized in 2005. Finally, "Didanodon altidens" has been assigned without comment to Lambeosaurus in two 21st Century reviews.
  During the late 1970s, Bill Morris was studying giant lambeosaurine remains from Baja California. He named them L.? laticaudus in 1981 (type specimen LACM 17715). Morris used a question mark in his work because no complete crest had been found for his species, and without it a definitive assignment could not be made. From what was known of the skull, he considered it to be most like Lambeosaurus. He interpreted this species as water-bound, due to features like its size, its tall and narrow tail (interpreted as a swimming adaptation), and weak hip articulations, as well as a healed broken thigh bone that he thought would have been too much of a handicap for a terrestrial animal to have survived long enough to heal. This species was later (2012) assigned to the new genus Magnapaulia.
caption: Profiles of various specimens, once assigned to their own species, now interpreted as different growth stages and sexes of L. lambei
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