Parasaurolophus, sometimes shortened to "para" or "parasaur", is an extinct genus of hadrosaurid dinosaur that lived during the Late Cretaceous in North America.
History[]
ROM 768, a partial skull and body missing most of the tail and hindlegs below the knees, is the holotype, found by a team from the University of Toronto in 1920 near Sand Creek in Alberta. It is from the Campanian Dinosaur Park, and named Parasaurolophus walkeri after Sir Byron Edmund Walker, the Chairman of the Board of Trustees of the Royal Ontario Museum where it was deposited, by William Parks. Only one partial skull was recovered from Dinosaur Park, with the genus notably rare in Alberta. 3 individuals from the same formation lacking skulls may be Parasaurolophus. Faunal lists mention P. walkeri in the Hell Creek Formation, which is Maastrichtian-aged. However, Sullivan and Williamson (1999) failed to mention this, and is obscure, with it likely being mistaken and the original meaning being the bank of Hell Creek, Missouri River. Charles H. Sternberg (1921) found P. tubicen type PMU.R1250, a partial skull, from the Kirtland Formation of New Mexico. It was sent to Uppsala, Sweden, where Carl Wiman (1931) named it as Parasaurolophus tubicen, meaning "trumpeter". NMMNH P-25100, a second and nearly-complete skull, was found in New Mexico in 1995, with Robert Sullivan and Thomas Williamson (1999) giving the genus a monographic treatment, reviewing anatomy and taxonomy. They also talked about what the crest was used for, where Williamson later published his taxonomic disagreement. John Ostrom (1961) described FMNH P-27393 from New Mexico as Parasaurolophus cyrtocristatus. This specimen includes a fragmentary skull and postcrania minus the feet, neck and parts of the tail. The name means "short-crested", found on top of the Fruitland Formation or (likely) the base of the Kirtland. David B. Weishampel and James A. Jensen (1979) described a partial skull, BYU 2467, from the Kaiparowits Formation. Since, more skulls have been discovered of this species, and its range has expanded.
Only one P. walkeri is referred, but more certainly exist. P. tubicen is the largest, having a long and straight crest, with an interior with an intensified complexity. P. cyrtocristatus is the latest and has a smaller, downturned crest that almost touches the neck. It was believed The latter was a juvenile of female form of P. walkeri or P. tubicen. However, age, distributor and anatomical features suggest it is distinct[1].
Material of cf. P. walkeri lost in the sinking of the SS Mount Temple. The pubis is diagnostic in species identification.
A cf. P. walkeri was identified from archived photos based on the pubis as being part of the cargo hold of the SS Mount Temple, a ship that sunk in the Atlantic in 1916 after a German submarine attacked her. The manifest were "hundreds" or "thousands" of unidentified fossils, 4 articulate hadrosaurs (one cf. P. walkeri, 2 Corythosaurus? or Prosaurolophus and a new species), a partial Champsosaurus skeleton (presumed; Sternberg's letters makes a typo), a Judithemys-like turtle (possibly a new species), a Boremys carapace, a Trionyx latus carapace, an unidentified hadrosaur skull and a fairly complete Chasmosaurus skull. All of these fossils were kept in the cargo hold and lost during the sinking. This cf. P. walkeri was recovered from a mystery quarry known as Quarry 196, which was discovered by Norwegian students who had listened to Darren Tanke talk about mystery quarries. Here, they recovered a negative glass plates that match photographs of the expedition, a marker that likely had a bright flag tied to it, a fragment of a Toronto newspaper, different styles of weaving, fragments mixed with plaster and burlap and eroded nails and wood used to build crates[2][3].
Description[]
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A diagram representing P. sp. in the Kaiparowits.
Preserved hyoid bone on P. walkeri.
Like Edmontosaurus, Parasaurolophus likely had pointed hooves. The elongated vertebrae on Parasaurolophus' spine supported a small sail, which was slightly arched. The large hollow crest on the head of Parasaurolophus is roughly one meter long, and ran down the face, and transitioned into the flat beak. For a hadrosaur, Parasaurolophus has relatively short forearms, a wide shoulder blade, and a heavily built pelvis and upper arm. P. walkeri has the classic crest, P. tubicen has a thicker crest and P. cyrtocristatus has a downturned crest similar to Tlatolophus[1]. In PaleoFest 2022, a slideshow presentation about the Grand Staircase and hadrosaur diversity talked about the presence of a P. sp. in the Kaiparowits Formation that overlaps with P. walkeri from the Dinosaur Park, and extends through the formation to the latest P. cyrtocristatus where it significantly overlaps. This morphotype has a crest morphology between the two mentioned species[4]. The hyoid, though undescribed, is large and suggests a developed tongue[5].
Paleobiology[]
NMMNH P-7145.
NMMNH P-7145 is a track from the Fossil Forest Member, Fruitland Formation that is 800x870 millimeters in size. Being only the second footprint from this area. Using Thulborn's formula, this trackmaker, which must be from a P. cyrtocristatus, is similar to the ichnogenus Carichnium but was not assigned to any taxon[6][7].
Ontogeny[]
A proposed cause of most injury, a tree falling on ROM 768 in a storm, fracturing ribs, splitting vertebrae apart and hitting its thorax.
Credit: Marzio Mereggia.
Paleopathology[]
Paleopathologies in ROM 768.
The holotype of Parasaurolophus, a specimen housed at the ROM (ROM 768), shows countless pathological elements. One is an oral lesion possibly related to periodontal disease, calluses over fractures on three dorsal ribs, a discoidal formation above neural spines 6 and 7, a spine oriented towards the skull in spine 7 that merges with 6, a V-shaped indent in 7 and 8 spines and a projection on the ilium which projects ventrally and fuses with the lateral iliac process. The lesion supports the theory that the individual suffered many traumatic events during life. The most prominent one mostly affects the anterior thorax. Many lesions are extremely rare in hadrosaurs, and could lead towards insight to their paleobiology and paleoecology. The ilium and iliac-related injuries are still unclear as to what caused them, although it likely has to do with the injuries to the anterior thorax. The discoidal formation above spines 6 and 7 also appears to have been caused by the injuries to the thorax, likely representing post-traumatic ossification at the base of the nuchal ligament. The gap between 7 and 8 is likely a stressful point between the nuchal ligament, which pulled 7 forward and 8 back. This large gap may have been caused by a large object falling on them, such as a tree, as proposed by authors in a figure[1].
Crest[]
Assorted P. cyrtocristatus crania.
Credit: Clumsystiggy on DeviantArt.
In 2021, remains of a P. cyrtocristatus skull, DMNH EPV.132300, revealed information about the interior of the peculiar Parasaurolophus crest. New research suggests the crest formed like many other hadrosaurs. The intricate shape showed how the animal breathed through eight feet of passage before going to the head. This feature likely resonated sound, which created a booming sound that communicated with other individuals. In 2017, a partial skull was recovered from the badlands of New Mexico. The area surrounding the skull shows that the rest of the body was once preserved, but has been worn down to the skull, several ribs and a mandible have survived until discovery. The fossil preserved the intricate bones in the crest, and is among the best-preserved P. cyrtocristatus skull [8]. A fully preserved P. cyrtocristatus skull is known from Utah, held at NHMU[9].
It was once thought the crest was used: as a snorkel, as a shoulder muscle anchor, regulation, resonating, species identification and as an anchor for a soft tissue frill. The snorkel was disproved due to no nostril at the tip and no nostril-closing muscles to retain air, archosaurs lack direct shoulder/crest muscle/ligament anchors and an unlikely presence of a crest frill. Behavioural and thermoregulatory functions, however, can not be disproved[1].
Vocalizations[]
Credit: Gabriel Ugueto.
Parasaurolophus had a large, hollow head crest likely used for broadcasting location and display. Scientists think that the hollow tube made a kind of trumpet sound when air passed through the nostrils, through the hollow space, and back.
Diet[]
Parasaurolophus was herbivorous, with teeth adapted to grinding tough foods similar to chewing. Teeth were constantly replaced, packed into thick batteries that contained hundreds of teeth. However, only a few teeth were ever used at the same time. The beak cropped vegetation and held in the mouth by cheek-like soft tissue. At maximum, it could have reached plants 4 meters from the ground. They were capable of more select feeding, with a diet of leaves, twigs and pine needles; this implies it was a browser. Some hadrosaurs may have snacked on small animals to supplement protein into their diet[10][1].
Classification[]
Parasaurolophus is a parasaurolophinin lambeosaurine hadrosaurid[1]. In 2021, this cladogram was recovered in the naming paper of Tlatolophus. They found Parasaurolophini splits into two trees: P. spp. and other parasaurolophinins. This further distinguished Charonosaurus as a valid genus[11]:
| Parasaurolophini |
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Synonyms[]
- P. jiayensis
- Paralophosaurus (lapsus)
- P. osborni
- P. tubicens (lapsus)[12]
Notable Specimens[]
- RAM 140000 "Joe": A juvenile P. sp. described in 2013. It was nicknamed "Joe" after a volunteer at the Raymond M. Alf Museum of Paleontology. It was found in the Kaiparowits in 2009 after a joint expedition by the museum and The Webb Schools. It died at ~1 year of age, being the most complete and youngest Parasaurolophus known; it is 2.5 meters long. Joe's skull is near-complete, lacking a piece of the maxilla on the left. The skull was split halfway down the center due to erosion, possibly due to the effects of decaying on a riverbed, Both sides are slightly displaced, with some bones scattered from the main block by erosion[1].
Paleoecology[]
Parasaurolophus lived in North America, with occurrences from Alberta, New Mexico, Utah and possibly Montana. P. walkeri are found in the Dinosaur Park Formation, P. cyrtocristatus and P. tubicen from the Fruitland Formation and other Parasaurolophus from the Kaiparowits Formation. There are rumors of a discovery in the Hell Creek Formation that paleontologists discovered remains of a lambeosaur, or possibly Parasaurolophus. If these rumors are true, it will expand the range of Parasaurolophus greatly[13][1]. However, the specimens associated from this formation, AMNH 5893[citation needed], is reported from the "Pierre Formation" on the bank of Hell Creek, Missouri River, which may actually represent the Bearpaw Formation. If this is true, then the range of Parasaurolophus would nonetheless expand[14].
Gallery[]
Fossils[]
Credit: David Evans.
Mounts[]
Credit: Clumsystiggy on DeviantArt.
Reconstructions[]
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References[]