Monday, 11 February 2013

L is for Lambeosaurus

Next up in our Albertan dinosaurian alphabet is 'L is for Lambeosaurus'. Lambeosaurus is another duck-billed dinosaur, or hadrosaur, from southern Alberta. Unlike last week's hadrosaur Kritosaurus, Lambeosaurus is known from many fossils and is very well known. 

Lambeosaurus was first named in 1923, despite some poorly preserved fossils being found and described about 20 years earlier by well-known Canadian palaeontologist Lawrence Lambe, which is where the name comes from. In fact, the type species is called Lambeosaurus lambei, with both the genus and specific epithet honouring for Lambe. It lived during the Late Cretaceous, about 75 million years ago. To repeat what I've said many times before about hadrosaurs, like others, it was capable of walking on two or four legs, or as we say, it was a 'facultative biped', which means it was capable of either. It was also a herbivore, and used its large 'battery' of teeth to grind down tough vegetation, and had a cheek-like structure that allowed it to chew its food. Another similarity to other hadrosaurs that I haven't mentioned previously is that it had 'ossified tendons' in its tail, which means the tendons were strengthened to keep the tail stiff. Lambeosaurus is also the type species for the group of hadrosaurs that typically have large, hollow cranial crests (the Lambeosaurinae), and it is no exception. These crests have a nasal cavity that runs through it, making it hollow, and was likely used to make noise for species recognition or social uses [1]. This is also supported by the fact that the crests are only present in adult individuals, and are not found in juveniles. 
Artists impression of Lambeosaurus magnicristatus showing the large cranial crest
Currently, only two species of Lambeosaurus are recognised, and they have only been found in Alberta. They are differentiated primarily by their crest. L. magnicristatus, as seen above, has an expanded blade-like crest, like a pompadour, while L. lambei has a thinner blade, and is described as a hatchet-like crest (as seen below). Lambeosaurus was about 9 metres in length, and 4 metres tall when standing on all fours. At one point, there were many species recognised, and several other species of smaller hadrosaurs were thought to be separate species. However, a re-evaluation of the groups showed that the smaller ones were actually juvenile Lambeosaurus, while other differences between species were thought to be sexual dimorphism [2,3]
Artists impression of possible growth stages and male/female variation within Lambeosaurus. Image by Nobu Tamura 
Both currently recognised species of Lambeosaurus are found in the Dinosaur Park Formation of southern Alberta. Other dinosaurs that live in this formation include ceratopsians (e.g. Centrosaurus and Styracosaurus, hadrosaurs (e.g. Corythosaurus and Parasaurolophus) and the theropod Gorgosaurus. This rock formation represents a highly diverse, and very well documented Late Cretaceous ecosystem, thought to be from a low-lying area with swamps, rivers, an floodplains [4]

That's it for Lambeosaurus! Next week, we'll talk about a ceratopsian dinosaur from southern Alberta. 

Other dinosaurs from Alberta that start with 'L':

1. Horner, J. R. et al. 2004. Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmolska, H. (eds) The Dinosauria (2nd edition). Berkeley: University of California Press pp. 438-463.
2. Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine dinosaurs. Systematic Zoology 24: 37-54.
3. Horner, J.R. 1979. Upper Cretaceous dinosaurs from the Bearpaw Shale (marine) of south-central Montana with a checklist of Upper Cretaceous dinosaur remains from marine sediments in North America. Journal of Paleontology 53: 566-577.
4. Eberth, D.A. The geology. Dinosaur Provincial Park. Indiana University Press, Bloomington (2005): 54-82.

No comments:

Post a Comment