Lambeosaurus: Beast of the Week

 This week we will be checking out another amazing hadrosaur.  Make way for Lambeosaurus!

Lambeosaurus was a hadrosaur ("duck-billed" dinosaur) that lived in what is now Canada during the late Cretaceous period, 75 million years ago.   Adults measured 23 feet (7 meters) long from beak to tail.  The genus name translates to "Lambe's Lizard" in honor of the paleontologist, Lawrence Lambe.  Like all hadrosaurs, Lambeosaurus would have eaten plants when alive.

Lambeosaurus lambei life reconstruction in watercolors by Christopher DiPiazza.

Lambeosaurus was a member of the lambeosaurine group of hadrosaurs, which are characterized by having more narrow snouts and often elaborate, hollow, bony crests on their heads.  Corythosaurus and Hypacrosaurus are two other members of this group which were particularly closely related to Lambeosaurus.  Within the Lambeosaurus genus there are actually two distinct species, Lambeosaurus lambei and Lambeosaurus magnicristatus.  Lambeosaurus lambei was discovered first, lived earlier by a few million years, and had a crest that jutted out in the front accompanied by a solid, bony, rod-like structure growing out of the back of its head.  Lambeosaurus magnicristatus lived slightly more recently, and had a larger, rounder crest that grew forward out of the top of its skull. 

There are two species of Lambeosaurus.  Lambeosaurus lambei (left) and Lambeosaurus magnicristatus (right). 

The exact function of Lambeosaurus' crest may always be a mystery, but many experts agree it most likely evolved for some sort of display within the species.  The front portion of the crest was also hollow, and attached to the nasal cavities of the animal, so it is commonly suggested they had a role to play in making unique sounds, as well.  Among Lambeosaurus lambei specimens, there seems to be a variety in crest size between individual adults.  Some paleontologists believe that this represents sexual dimorphism, the males with slightly larger crests than the females.  Babies and juveniles are also known from Lambeosaurus, which had tiny crests that start in the front of the skull, and expanded backward as the animals matured. 

Skull cast of Lambeosaurus lambei on display at the Academy of Natural Sciences in Philadelphia.

Lambeosaurus had a very long, slender snout that was tipped with a rounded bill.  This feature would have been ideal for clipping tough vegetation that would then be ground up by many small teeth in the back of the mouth, which acted together as a unit, called a dental battery.  Like all reptiles, Lambeosaurus would have been able to regenerate teeth continuously as they became worn or lost.  

Baby Lambeosaurus skull on display at the Royal Tyrrell Museum. (photo credit: Roland Tanglao)

Like all hadrosaurs, Lambeosaurus would have been able to walk on all fours or just its hind legs, as a biped, depending on what suited it.  Its front limbs were relatively the middle three fingers on each hand were fused together and tipped with a large hoof-like claw.  Its tail was long and extremely robust, and would have served as a counterbalance for the animal if it walked or ran on its hind legs.  The tail also could have served as an effective weapon to keep predators away or even knock them over if swung hard enough, if needed.  

References

Dodson, Peter (1975). "Taxonomic implications of relative growth in lambeosaurine dinosaurs". Systematic Zoology. 24 (1): 37–54.Simpson, D.P. (1979). Cassell's Latin Dictionary (5th ed.). London: Cassell Ltd. p. 883. 

Evans, David C.; 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.

Horner, John R.; Weishampel, David B.; Forster, Catherine A. (2004). "Hadrosauridae". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria(2nd ed.). Berkeley: University of California Press. pp. 438–463.