modafinil to buy online Name Meaning: Near Crested Lizard
can you buy tinidazole over the counter Geologic Era: Late Cretaceous (76-73 million years ago)
Location Discovered: Alberta, Canada
Range: Canada through New Mexico (possibly China as well)
Size: 9.5 meters long (type specimen)
Extinction: 73 million years ago
Parasaurolophus is one of the more poorly understood hadrosaurs, due to lack of specimens and it seeming to be comparatively rare in the fossil record. Three species have been described, two having skulls like the one pictured below, and a third with a smaller, shorter, more rounded crest. It has been hypothesized that the shorter crested species may be the female of the other two species. If this the case, it would be a wonderful example of sexual dimorphism. This relationship could be better understood if we had more skulls to study other than the six on record.
The purpose of this prominent crest was under speculation for some time. Ideas ranged anywhere from a snorkel to a reservoir for a volatile chemical (so the animal could spit fire). A more likely scenario is that it was used for complex vocalizations. The interior of the crest is hollow, and connects to the airway. Many recreations have been done of the possible sound Parasaurolophus could have made. For those who are musically inclined, most of them sound like a cross between a French horn and a baritone horn.
All of the Parasaurolophus crests studied have slightly different twists and turns on the interior of the crest. This may mean that each individual had its own particular voice, much as humans do. These sounds could have been made to be quite loud, and could likely be heard miles away. In addition to helping with individual identification, it may have helped with cross species identification, as several types of hadrosaurs lived in the same area. If this was the case, Western North America and Canada was a very loud, musical place.
A second purpose for the crest could have been visual identification. Most hadrosaurs (and dinosaurs in general) had good eyesight. A large, distinctive crest is a good visual indicator of different species, especially if similar animals are living in the same area. Many hadrosaurs were similar in size and build, so having a defining feature would have been helpful in terms of figuring out who to mate or move with.
This is the only mostly complete skeleton of Parasaurolophus walkeri, and it does have a very interesting pathology on the vertebral column. The V shaped between the 7th and 8th rib should not be there. In addition, the dorsal processes on the vertebrae anterior to this notch look abnormal. They look like they have been damaged, either broken and healed or infected and healed, or possibly all of these. My first inclination for this pathology is an injury due to a predator, the most likely culprit being Albertosaurus.
It is possible that this individual was attacked by a predator in its youth, and was lucky enough to escape with its life (albeit missing a few pieces and parts). The attack left scars, and this animal is also lucky that it did not succumb to secondary infection. This is probably not the case, as these injuries look old, with little other evidence of trauma or scavenging. So the most likely scenario is that this animal had an encounter with a large predator and lived to tell the tale.
Crest Comparison:”Parasaurolophus skulls” by Ostrom, John H. – http://digitallibrary.amnh.org/dspace/handle/2246/1260. Licensed under Public Domain via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Parasaurolophus_skulls.jpg#/media/File:Parasaurolophus_skulls.jpg
Full Skeleton:”Parasaurolophus walkeri” by missbossy from Singapore, Singapore – DinosUploaded by FunkMonk. Licensed under CC BY 2.0 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Parasaurolophus_walkeri.jpg#/media/File:Parasaurolophus_walkeri.jpg
Reconstruction:”Sketch parasaurolophus” by Tim Bekaert – Own work. Licensed under Public Domain via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Sketch_parasaurolophus.jpg#/media/File:Sketch_parasaurolophus.jpg