Lambeosaurus

*Lambeosaurus lambei*

***Lambeosaurus*** was a crested, duck-billed dinosaur. Its forward-leaning, hollow, bony crest was as big or bigger than the rest of its skull and may have been used to produce sounds, enhance its sense of smell, and/or used in courtship displays. These types of dinosaurs were of the same hadrosaur type as some of the other types who lived near water. Scientists think it lived around North America around 76-75 million years ago.

## Description

*Lambeosaurus*, best known through *L. lambei*, was quite similar to the more well-known *Corythosaurus* in everything but the form of the head frill. Compared to *Corythosaurus*, the crest of *Lambeosaurus* was shifted forward, and the hollow nasal passages were at the front of the crest and stacked vertically. It also can be told apart from *Corythosaurus* by its lack of forking nasal processes making up part of the sides of the crest, which is the only way to tell juveniles of the two genera apart: the crests took on their unique forms as the animals aged.

In build, *Lambeosaurus* was like most hadrosaurids, and could move on both two legs and all fours, as shown by footprints of related animals. It had a long, stiff tail that kept it from drooping. The hands had four fingers, lacking the innermost finger of the generalized five-fingered tetrapod hand, while the second, third, and fourth fingers were bunched together and bore hooves, suggesting the animal could use the hands for support. The fifth finger was free and could be used to manipulate objects. Each foot had just the three central toes.

The most unique feature, the crest, was different in the two well-known species. In *L. lambei*, it was taller, narrower, more rectangular, and had a secondary point raising backwards and was a bit shorter and more rounded in females. In *L. magnicristatus*, the crest was more rounded with no secondary point, but was strikingly big and pointed a bit forwards. In the lesser-known species "L." *laticaudus* and *L. paucidens* the crest is not yet known, but "L." *laticaudus* can be known by its great size and the tall form of its tail.

*Lambeosaurus* grew to be about 30–50 feet long (9–15 m), weighing 5.6 tons. It is the largest-known duck-bill dinosaur

## Classification

*Lambeosaurus* is the type genus of the Lambeosaurinae, the subfamily of hadrosaurids that had hollow skull crests. Among the lambeosaurines, it is closely related to *Corythosaurus* and *Hypacrosaurus*, with little separating them but crest form. The relationships among these dinosaur genera are hard to pick out. Internet classifications sometimes include all three in the tribe Lambeosaurini, but such a tribe has not been formally defined. Instead, the equivalent clade Corythosaurini has been adopted in publications, including David Evans and Robert Reisz's redescription of *L. magnicristatus*. This examination indicated that *Lambeosaurus* is the sister taxon to a clade made up of *Corythosaurus*, *Hypacrosaurus*, and the Russian genus *Olorotitan*; these lambeosaurines, with *Nipponosaurus*, make up Corythosaurini.

## Discovery

*Lambeosaurus* was named by Dr. William A. Parks in 1923 to honor Lawrence Lambe, an early Canadian fossil hunter. Many fossils have been found in North America, including Montana (USA), Baja California (Mexico), and Alberta (Canada).

## Paleobiology

### Feeding

As a hadrosaurid, *Lambeosaurus* was a large bipedal/quadrupedal herbivore, eating plants with an advanced skull that let it grind like mammals chew. Its teeth were replaced all the time and were packed into dental batteries that each had more than 100 teeth, a few of which were in use at a time. It used its beak to crop plants, which were hel in the jaws by a cheek-like organ. It would have fed from the ground up to around 13 ft above. As noted by Bob Bakker, lambeosaurines have narrower beaks than hadrosaurines, meaning that *Lambeosaurus* and its relatives could feed on what they liked.

### Cranial crest

Like other lambeosaurines such as *Parasaurolophus* and *Corythosaurus*, *Lambeosaurus* had a unique crest on the top of its head. Its nasal cavity ran back through this crest, which made it mostly hollow. Many suggestions have been made for the function or functions of the crest, like to house salt glands, boost the sense of smell, use as a snorkel or air trap, make sounds, or to recognize one another. Social functions such as noisemaking and recognition have become the most widely accepted of the various hypotheses.

The large size of hadrosaurid eye sockets mean it had good sight and, proof that sight was important to these animals. The hadrosaurid sense of hearing seems to be strong to. There is at least one example, in the related *Corythosaurus*, of a slim ear bone in place, which mixed with a large space for an eardrum implies a sensitive middle ear. This means that the hearing part of the inner ear was well-developed. If used to make noise, the crest could also have been different between species or sexes, because the differing layouts of the nasal passages corresponding to the different crest shapes would have made naturally different sounds.

## JPInstitute.com Description

Lambeosaurus was a large duck-billed, plant-eating hadrosaur that grew a little bigger than most of the meat-eaters of its time. It walked on all four legs much of the time, but it could also stand easily on its hind legs, as they were much larger than its front legs. Like other members of its family, it had a lot of teeth packed into its cheeks - some had over 1,000! It also had a distinctive crest on top of its head that pointed forward and seems to have varied by animal.

Hadrosaurs were among the most common herbivores of the late Cretaceous. Like other hadrosaurs, it had a beak that was covered with a horny sheath. Lambeosaurus was found as early as 1889, but was not recognized until 1924 as a separate genus. All species had a distinctive, hollow hatchet shaped crest - L. lambei also had a short spike that projected back from the crest.

## Links

http://web.archive.org/web/20040214165023fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_lambe.html#

## References

Template:References

1. ↑ 1.0 1.1 Dodson, Peter (1975). "Taxonomic implications of relative growth in lambeosaurine dinosaurs". Systematic Zoology 24 (1): 37–54. doi:10.2307/2412696. JSTOR 2412696.
2. ↑ Evans, David C.; Forster, Catherine F.; and Reisz, Robert R. (2005). "The type specimen of Tetragonosaurus erectofrons (Ornithischia: Hadrosauridae) and the identification of juvenile lambeosaurines". In Currie, Phillip J., and Koppelhus, Eva. Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 349–366. ISBN 0-253-34595-2.
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Horner, John R.; Weishampel, David B.; and Forster, Catherine A (2004). "Hadrosauridae". In Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 438–463. ISBN 0-520-24209-2.
4. ↑ Lull, Richard Swann; and Wright, Nelda E. (1942). Hadrosaurian Dinosaurs of North America. Geological Society of America Special Paper 40. Geological Society of America. pp. 193–194.
5. ↑ Evans, David C.; and Reisz, Robert R. (2007). "Anatomy and relationships of Lambeosaurus magnicristatus, a crested hadrosaurid dinosaur (Ornithischia) from the Dinosaur Park Formation, Alberta". Journal of Vertebrate Paleontology 27 (2): 373–393. doi:10.1671/0272-4634(2007)27[373:AAROLM]2.0.CO;2.
6. ↑ Bakker, Robert T. (1986). The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and their Extinction New York: William Morrow. p. 194. ISBN 0-8217-2859-8.
7. ↑ 7.0 7.1 Hopson, James A. (1975). "The evolution of cranial display structures in hadrosaurian dinosaurs". Paleobiology 1 (1): 21–43. JSTOR 2400327.
8. ↑ Norman, David B. (1985). "Hadrosaurids II". The Illustrated Encyclopedia of Dinosaurs: An Original and Compelling Insight into Life in the Dinosaur Kingdom. New York: Crescent Books. pp. 122–127. ISBN 0-517-46890-5.
9. ↑ Weishampel, David B. (1981). "Acoustic analyses of potential vocalization in lambeosaurine dinosaurs (Reptilia: Ornithischia)". Paleobiology 7 (2): 252–261.