Lambeosaurus

Credit: Connor Ashbridge on the Wikimedia Commons.

*Lambeosaurus* is an extinct genus of lambeosaurine hadrosaurid dinosaur that lived in Canada and the United States during the Late Cretaceous.

## History

Lawrence Lambe (1902) named GSC 419, a limb, as *Trachodon marginatus* and GSC 1092, a left upper jaw, as *Trachodon altidens*. In the same volume, Henry Fairfield Osborn termed the latter as a new genus he coined as "Didanodon" without discussion. In the same areas in the 1910s, better remains were found and Lambe assigned 2 new skulls to the former species, coining *Stephanosaurus* as a new genus to house the species in 1914. Since remains were scrappy and the skulls were tentatively assigned to them, William Parks (1923) coined *L. lambei* to house GSC 2869 (now NMC 2869) as the holotype and was after Lambe, who had died 4 years previous. The same paper coined Lambeosaurinae as a replacement for Stephanosaurinae. Some species were named based on individual variation, age, sex or taphonomical circumstances. These are *T. cranibrevis*, named from GSC-870f (now NMC-8705), a partial skeleton and skull, now seen as invalid; *L. magnicristatum* (corrected to *L. magnicristatus* in 1937) based on a smaller skull GSC-8705 (now NMC-8705); and *L. clavinitialis*, based on a smaller crest and reduced spine projecting from its back, which has been doubted. *Corythosaurus frontalis* was recombined by Parks (based on GSC 5853; now ROM 869) as a specimen of *Lambeosaurus*. Ostrom (1964), after a long abscence of any new material description, noted that Marchs USNM 5457, which he named *Hadrosaurus paucidens*, was likely a specimen of *Lambeosaurus*.

Peter Dodson (1975) examined why so many lambeosaurines are known from such a short interval and area, doing a morphometric study where many skulls were examined, finding many invalid species and genera. Dodson found *L. clavinitialis* may be a female *L. lambei*, with *Corythosaurus frontalis* and *Procheneosaurus preceps* likely being juveniles. *L. magnicristatus* was found to be distinct. The other two *Procheneosaurus* species were found to be juvenile corythosaur. This would be widely accepted, and *L. lambei* is known from at least 17 individuals (7 skulls and postcrania and 10 skulls), *L. clavinitialis* is still regarded by most as synonymous, but others suggest separation. Some have suggested that *L. clavinitialis* skulls without a spine on the crest are *L. magnicristatus*, but a 2007 redescription of *L. magnicristatus* rejects this. *L. magnicristatus* was named by Sternberg (1935) based on 2 skulls, with most of the articulat skeleton preserved with the type specimen being lost and most of the specimen was bears water damage during storage and discarded in description. Other skeleal elements of this species were lost. It is slightly younger than *L. lambei* and its name means "large-crested". A lambeosaurine jaw from the Bearpaw Formation described by Jack Horner may be an *L. magnicristatus*, being the first lambeosaur from marine rocks. More *Lambeosaurus* remains were later documented from the Bearpaw, of all species. Bill Morrus (1970s) named *L.? laticaudus* (uncertain because the type, LACM 17715, lacked a crest) as an aquatic species based on its collection data and its tall, narrow tail and its small size as a possible marine adaptation. In 2012, it was moved into a new genus called *Magnapaulia*.

## Description

*Lambeosaurus* is best known through *L. lambei* and is similar to *Corythosaurus* in most features minus the ornamentation. Compared to it, *Lambeosaurus* crest is forwards shifted and vertically stacked hollow nasal passages. The only way to tell the two apart in juveniles is through the distinct ways the crest is formed during development. *Lambeosaurus* was much like other hadrosaurids. *L. lambei* has a hatchet-like crest shape in adults and is more rounded in immature individuals. The "blade"-like region was in front of the eyes and the "handle" or spine is a solid bony rod that jutted from its posterior. The top portion of the "blade" was a thin bony coxcomb that grew in later in life near to adulthood. The lower portion had hollowed spaces that continued the nasal passages. The "handle" in *L. magnicristatus* is shortened and the "blade" is expanded, which makes a large pompadour-like crest. The best specimen of this species has a damaged crest, preserving only the first half. Large adults are ~7 meters long, and skin impressions are known. This shows that its thin skin had many small, uniform, polygonal scutes and was recovered from the neck, torso and tail. Similar integument is known from the neck, forelimb and foot of *L. magnicristatus*.

## Classification

*Lambeosaurus* is the type of lambeosaurinae, which contains lambeosaurini with *Lambeosaurus* and similar genera. This was once called corythosaurini, but this was found by Evans and Reisz to be sister to a clade with *Corythosaurus* and *Hypacrosaurus*. ICZN rules thus support the renaming of this clade to lambeosaurini, making the former a synonym. Albert Prieto-Márquez, Luis M. Chiappe and Shantanu H. Josh (2012) find the following:

## Paleobiology

Many have suggested uses for the crest, such as holding salt glands, improving smell, as a snorkel, species recognition and as a resonating chamber. Social functions and resonating are most commonly accepted. The sclerotic rings and large orbits suggest it was diurnal with improved sight. It likely had good hearing. Relatives have a well developed auditory portion. Individuals of different age or sex would have made distinguished sounds because the internal layout was different.

### Diet

*Lambeosaurus* had a large dental battery and was able to chew similarly to mammals by grinding food. These teeth were replaced over time and each battery contained 100s of teeth, but only a few were used at once. It could feed up to 4 meters from the group by cropping food using its beak and holding the plants in its jaws through cheek-like structures. Lambeosaurines have narrower beaks, which suggests more selective feeding.

## Synonyms

* *Procheneosaurus*
* *Tetragonosaurus*
* *Trachodon altidens*
* *Corythosaurus frontalis*
* *L.? laticaudus*
* *L. magnicristatum* (amended)
* "Didanodon"
* *L. paucidens*
* *Hypacrosaurus magnicristatus*
* *Hypacrosaurus lambei*
* *Hypacrosaurus clavinitialis*

## Notable Specimens

* "George" or "Walking *Lambeosaurus*"[*citation needed*]: Discovered in 1913 by Charles Sternberg and his sons from Red Deer Valley, Alberta, George was brought to the National Museum of Canada and permanently loaned to to the Pacific Museum of the Earth at the University of British Columbia since 1950. Dr. F.J. Alcock authorized this transaction. Since then, George has been on display. Most of the postcrania belong to a male but the head is of a similarly-sized female. One of the toes was restored.
* "Maggie": A juvenile *L. lambei* skull[*citation needed*].
* Badlands Dinosaur Museum coll.: A skull, representing the oldest Lambeosaurus, and the only specimen from the United States. It was discovered by Denver Fowler in July 2021.

## Paleoecology

*L. lambei* and *L. magnicristatus* are both known from the Dinosaur Park Formation and are differentiated by stratigraphy. This formation carries a large fauna with other hadrosaurs, ceratopsians, tyrannosaurids and ankylosaurs, The climate here was warmer than Alberta is today, had no frost and had wet and dry seasons. Conifers were canopy plants and ferns, tree ferns and angiosperms formed the undergrowth. *L. lambei* is known from the upper third and *L. magnicristatus* are at the very top of the formation, where it was rarer and it is more marine.

## References

* https://en.wikipedia.org/wiki/Lambeosaurus
* https://twitter.com/DavidEvans\_ROM/status/1471868541053947907/photo/1
* https://paleobiodb.org/classic/basicTaxonInfo?taxon\_no=53394
* https://paleobiodb.org/classic/displayStrata?geological\_group=&formation=Bearpaw&group\_formation\_member=Bearpaw
* https://gizmodo.com/the-story-of-george-1573889760
* https://pme.ubc.ca/george-the-lambeosaur/
* https://archive.org/details/g.s.paul2016theprincetonfieldguidetodinosaurs/page/n258/mode/1up

1. ↑ https://twitter.com/df9465/status/1484370313928318983/photo/1