Episode 148 is all about Lambeosaurus, a hadrosaurid with a “hatchet blade” crest.

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In this episode, we discuss:

News:

The dinosaur of the day: Lambeosaurus

Hadrosaurid that lived in the Late Cretaceous in what is now North America

Name means “Lambe’s lizard” (named in honor of Lawrence Lambe)

Described in 1923 by William Parks

But Lawrence Lambe spent 20 years studying the first material

Multiple species have been named (from Alberta, Canada, Montana, U.S., and Baja California, Mexico) but only two Canadian species are considered valid

Has a long history…

At one point there were seven species of Lambeosaurus. Some of them have been determined to be different sexes of already named hadrosaur genera

Lawrence Lambe described the first Lambeosaurus fossils in 1902 (post cranial skeleton, no skull), but he assigned them to Trachodon marginatus (Trachodon is a dubious genus). Then in 1914, he described two new skulls that he thought should be Trachodon marginatus, but since Trachodon was dubious he created a new genus, Stephanosaurus. The skulls came from around the same area as the Trachodon marginatus fossils, so it means they could all be the same type of dinosaur, but it’s not for certain. Because of this, in 1923 William Parks redescribed the Stephanosaurus skulls as Lambeosaurus, and named them in honor of Lawrence Lambe, who had died in 1919

A number of fossils that were originally classified as other dinosaurs have now been determined to be Lambeosaurus. In 1902, Henry Fairfield Osborn named Didanodon altidens, based on a partial left jaw. Lawrence Lambe reclassified it as Trachodon altidens.

In 1917 Lawrence Lambe named a new dinosaur Cheneosaurus, which became the type genus of the group Cheneosaurinae (group of dinosaurs that looked like hadrosaurs, but were smaller)

In 1920 William Diller Matthew named a new dinosaur Procheneosaurus, based on a photograph of a skeleton. Later William Parks described Tetragonosaurus from fossils found in Dinosaur Park Formation, and included fossils from Procheneosaurus into the type species, Tetragonosaurus praeceps. Two other species were added to Tetragonosaurus: erectofrons and cranibrevis

Then in 1942 Richard Swann Lull and Nelda Wright did a study about all these dinosaurs, and said that all Tetragonosaurus should be Procheneosaurus, and that Trachodon altidens could also be Tetragonosaurus. Lull got approval from the ICZN to use the name Tetragonosaurus instead of Procheneosaurus

Charles Marsh named a genus, Hadrosaurus paucidens, based on a partial maxilla and squamosal from the Judith River Formation in Montana. In 1964 John Ostrom said it was probably a Lambeosaurus

Only post cranial remains have been found of Lambeosaurus paucidens, so it’s not clear if it is a Lambeosaurus

In 1975 Peter Dodson found that Cheneosaurinae (which included Procheneosaurus) were actually juveniles of larger hadrosaurs, and that the type specimen of Procheneosaurus was actually a juvenile Lambeosaurus (the others were juvenile Corythosaurus). He found this by measuring dozens of skulls and interpreted the differences as being juvenile or male or female

Interestingly, Procheneosaurus was named before Lambeosaurus, and usually the older name is the one that sticks (but not in this case)

Bill Morris named Lambeosaurus laticaudus (with a question mark) in the 1970s. They were lambeosaurine remains in Baja California, but no complete crest was found, so it’s not known for sure if it’s a Lambeosaurus (he based it on the parts of the skull that were found). In 2012 it was assigned to a new genus, Magnapaulia

Now there are two valid species: Lambeosaurus lambei (type species) and Lambeosaurus magnicristatus

Lambeosaurus lambei and Lambeosaurus magnicristatus were from the Dinosaur Park Formation (though they lived at slightly different times)

Part of the family Lambeosaurine, the subfamily of hadrosaurids with hollow crests

Closely related to Corythosaurus, Hypacrosaurus, Olorotitan (all very similar but have slightly different crests)

Lambeosaurus crest was shifted forward, and hollow nasal passages were in the front of the crest and stacked vertically

Crest was different in each species of Lambeosaurus

Lambeosaurus lambei had a crest that was hatchet-like in shape in adults, and shorted and more rounded in specimens thought to be females

The “hatchet blade” is in front of the eyes, and had two sections (an upper portion, of a thin bony “coxcomb” that developed right before adulthood, and a lower portion that had hollow spaces that were part of the nasal passages). Also had a “handle” that was a solid bony rod that went over the back of the skull

In Lambeosaurus magnicristatus, the “handle” was smaller and the “blade” was larger (though this crest is damaged in the most complete specimen, and only the front half is left)

There are a few theories about what the crest was used for: one is it was like a snorkel or air chamber so Lambeosaurus could keep its head underwater for long periods of time (but that would mean it was often in water, and doesn’t explain why Lambeosaurus crest looks different from other lambeosaurines), another is it stored salt glands, but salt glands are usually in animals that live in saltwater ecosystems (though areas where Lambeosaurus have been found were near the Western Interior Sea, which was salt water) and in 1979 Jack Horner described what looks like a Lambeosaurus magnicristatus jaw from marine sediment, though this doesn’t explain why other hadrosaurs were in different ecosystems (not just saltwater) and it doesn’t explain why the crest looks different between Lambeosaurus species

Another theory is that crests were used for display, so they could tell their species apart, and as a sign of maturity, since adults had more developed crests (also specimens scientists think are females have more rounded crests than males)

The crest may also have been used to create sounds (probably most popular theory now)

Dodson suggested that Lambeosaurus had sexual dimorphism, based on their crests

However, David Evans and Robert Reisz re-examined the skulls Dodson had looked at, and suggested that it was too small of a sample size and there was an incomplete fossil for Lambeosaurus magnicristatus. Dodson had looked at only two individuals of Lambeosaurus magnicristatus, and found that one of them had a larger crest (and based on that, suggested there was sexual dimorphism). But Evans and Reisz found that the female crest was broken, and that’s the only reason it seemed smaller, and if it weren’t broken, they would have looked the same

Other paleontologists, such as James Hopson, suggested that Lambeosaurus lambei were females and Lambeosaurus magnicristatus were males (but the species were not found at the same stratigraphic level)

Lambeosaurus was both bipedal and quadrupedal

Had four digits on each hand, and the second, third, and fourth digits were together and bore hooves (so could go on all fours for support)

Last digit on the hand was free, and could be used to help with grip or balance

Had three digits on each foot

Because it was both bipedal and quadrupedal, Lambeosaurus could eat low to moderately high growing vegetation

Lambeosaurus had a narrow front of the mouth, which may mean it was a picky eater

Had batteries at the back of the mouth with over 100 teeth to grind plant matter

About 31 ft (9.4 m) long

Some scale impressions have been found

Found polygonal scutes on the neck torso and tail (on Lambeosaurus lambei) and on the neck, forelimb, and foot (on Lambeosaurus magnicristatus)

Had a long, stiff tail, with ossified tendons

Had large eye sockets and sclerotic rings, which means it probably had good vision and was diurnal

Also had a strong sense of hearing (based on Corythosaurus, a close relative, having a slendar stapes (reptilian ear bone) and large space for an eardrum

Lived near rivers and floodplains, with wet and dry seasons

Other animals that lived around the same time and place as Lambeosaurus include Corythosaurus (though Corythosaurus may have lived earlier than Lambeosaurus, and Lambeosaurus may have even replaced Corythosaurus), Chasmosaurus and Centrosaurus (ceratopsians), Edmontonia (nodosaur), Euoplocephalus (ankylosaur), as well as the tyrannosaurs Albertosaurus and Daspletosaurus

Fun Fact:

Pangaea would have caused very different weather across the continents than we see today. The beaches in Brazil would have been (approximately) connected to Cote d’Ivoire, Ghana, Nigeria, and all the way down to about Angola on west side of Africa. Argentina and Uruguay were up against Namibia, South Africa & a bit of Antarctica. The curve of North America from Newfoundland to Florida would have blocked off the rest of West Africa.

There was no Caribbean Sea

Weather would have been much more erratic, like the Midwest in the US, which doesn’t benefit from oceans keeping temperatures more consistent

There were likely some huge desserts on Pangaea

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