About Parasaurolophus
| Scientific Name (Genus) | Parasaurolophus |
| Meaning of Name |
Near crested lizard (or Lizard near Saurolophus)
para (near) [Greek] - sauros (lizard) [Greek] - lophos (crest) [Greek] |
| Classification | Ornithischia, Ornithopoda (Hadrosauridae, Lambeosaurinae) |
| Total Length | Approx. 9.5 - 10m (Estimated weight: Approx. 2.5 - 5 tons) |
| Diet | Herbivorous |
| Period | Late Cretaceous (Campanian stage: approx. 76.5 to 73 million years ago) |
| Sub-classification / Species Name |
Parasaurolophus walkeri
Parasaurolophus tubicen Parasaurolophus cyrtocristatus |
| Year of Paper Publication | 1922 |
| Genus Name Publication |
Parasaurolophus walkeri, a new genus and species of trachodont dinosaur.
University of Toronto Studies: Geological Series. 13 by William A. Parks. 1922. |
Characteristics of Parasaurolophus
Parasaurolophus was a large ornithopod that lived in North America (Laramidia) during the Late Cretaceous period.
The genus name means "near crested lizard" (or lizard near Saurolophus), but it is classified in a different subfamily (Lambeosaurinae) from Saurolophus (Hadrosaurinae or Saurolophinae). Their similar appearance is thought to be an accidental resemblance through the process of evolution (convergent evolution).
The most distinguishing feature of Parasaurolophus is the long, hollow, tubular crest extending backwards from its head. The role of this crest was shrouded in mystery for many years, and various hypotheses such as "a snorkel for breathing underwater," "an air reservoir," and "a brain cooling device (thermoregulation)" were once proposed.
However, the theory that it served a dual function as a "visual display (a symbol for recognizing members of the same species)" and an "acoustic resonance chamber (vocal organ)" is widely supported today.
Digital acoustic simulations using CT scans of well-preserved skulls have shown that this crest, with its complex airway structure, could produce low-frequency sounds like a giant trombone. Because low-frequency sounds travel well over long distances even with obstacles, they were ideal for communicating with peers in the forest and warning of danger. Furthermore, their inner ears were specifically structured to hear low-frequency sounds.
In addition, the mouth of Parasaurolophus had a powerful chewing organ called a "dental battery," consisting of hundreds of tightly packed teeth. Recent analysis of microwear (scratches on teeth) indicates that Parasaurolophus performed a complex chewing motion, moving its lower jaw back and forth with a slight rotation like a mammal. This allowed them to efficiently grind up the tough plants of their time.
Regarding their gait, it is thought that they walked on all fours when moving slowly or eating plants, but switched to bipedal running when moving quickly, such as when escaping from carnivorous dinosaurs. A network of "ossified tendons" crisscrossed from their back to their tail, which functioned as a powerful engine for running their large bodies by keeping their tails straight.
As for the skin, partial impression fossils have been found, showing that they were covered with uniform, nodular round scales without acorn-like protrusions.
Baby Parasaurolophus
In 2009, a juvenile fossil of Parasaurolophus affectionately known as "Baby Joe" was discovered in the Kaiparowits Formation in Utah, USA, and reported in a paper in 2013. Cataloged as specimen number RAM 14000, this juvenile was about 2.5 meters long (about 25% the size of an adult). Analysis of its bone tissue revealed that it was less than a year old and in a period of rapid growth.
Its crest was not long and tubular like an adult's, but low and semi-circular. Notably, while other closely related dinosaurs did not develop crests until they reached about half the size of adults, this juvenile had already begun to form a crest and internal airways at a small stage of less than 25% of an adult's size. This suggests that "vocal communication" was extremely essential for the survival of Parasaurolophus from the juvenile stage.
The actual fossil was exhibited at [Dino Expo 2016] held at the National Museum of Nature and Science in 2016.
Discovery and Description
In 1920, during a field trip by the University of Toronto, Canada, to the Late Cretaceous strata - the Dinosaur Park Formation along the Red Deer River in Alberta, a partial skeleton including a distinctive skull was discovered.
Source: Parasaurolophus walkeri, a new genus and species of trachodont dinosaur.
University of Toronto Studies: Geological Series. 13
by William A. Parks. 1922.
In 1922, based on the fossils discovered at this time (specimen number ROM 768), William A. Parks, a paleontologist at the University of Toronto, described the new genus and species Parasaurolophus walkeri. The species name "walkeri" was given in honor of Byron Edmund Walker, who contributed to the development of cultural and educational projects at the University of Toronto and other institutions.
Currently, three species of the genus Parasaurolophus are considered valid.
The second species was discovered in the Kirtland Formation in New Mexico, USA, and described as Parasaurolophus tubicen by Carl Wiman in 1931. This species is characterized by its complex, maze-like internal airway branches in the crest.
The third species is Parasaurolophus cyrtocristatus, described by John Ostrom in 1961. Because its crest is short and curves sharply downwards, there was a long debate over the sexual dimorphism hypothesis, suggesting it might be a "female or a young individual of other species." However, recent research has revealed that it has unique skull features and that the geological age of the strata in which it lived is different (found in lower, older strata), so it is now considered an independent valid species.
A detailed examination of the first discovered Parasaurolophus fossil (specimen number ROM 768) revealed that this individual had suffered severe injuries (such as broken ribs and pelvis), similar to a fallen tree directly hitting its chest while it was alive, yet it survived for months or even years afterwards.
Furthermore, the bones of its neck and back indicate that the giant ligament (nuchal ligament) supporting its neck was strongly developed. In the past, reconstructive drawings were sometimes made based on the hypothesis that a "skin flap (frill) stretched from the tip of the crest to the back," but this "skin flap hypothesis" is now rejected due to the robust structure of the neck and the fact that it would have restricted the free movement of the neck.
Parasaurolophus Stamp & Fossil Gallery
