The discovery of the jaw discovering new Dinosaur skull reveals the evolution of a bizarre crest

• The first new skull of a rare species of the dinosaur Parasaurolophus (recognizable by the large hollow tube that grows on its head) was discovered in 97 years.
• Beautiful preservation of the new skull gives paleontologists their first opportunity to definitively identify how such a bizarre structure grew on this dinosaur.
• For the first time, this study found characteristics related to crown dinosaur species found in southern North America (New Mexico, Utah), as opposed to the only northern species (Alberta).
• The environment, in northwestern New Mexico, is dated to about 75 million years ago, a time when North America was divided by a shallow sea and teeming with dinosaurs with ducklings, horned dinosaurs and early tyrannosaurs.
• Fossils from the region are part of the natural heritage of the peoples Diné (Navajo Nation) and Puebloan. The new fossil Parasaurolophus, from Bureau of Land Management Wilderness Lands in northwestern New Mexico, emphasizes the importance of protecting public lands as natural laboratories and repositories for scientific discovery.

The first new skull discovered in almost a century from a rare species of the iconic tube-moving dinosaur Parasaurolophus was announced in the journal today PeerJ. The superior preservation of the skull, especially the bizarre tubular nasal passage, finally revealed the structure of the crest after decades of disagreement.

Despite the extreme morphology, the details of the sample show that the crest was shaped like the crests of other, related dinosaurs with ducks. Joe Sertich, curator of dinosaurs at the Denver Museum of Nature & Science and the leader of the team that discovered the monster, said, “This specimen is a wonderful example of amazing creatures that evolved from one ancestor.”

Imagine your nose enlarging your face, three feet behind your head and then turning around to pinch above your eyes. Parasaurolophus breathes through an eight-foot pipe before oxygen ever reaches its head, ”said Terry Gates, a paleontologist at North Carolina State University.

“For the past 100 years, ideas for the purpose of the exaggerated tubular weapon have ranged from snorkeling to super sniffers,” noted David Evans, the Temerty Chair in Vertebrate Paleontology and Vice President of Natural History at the Royal Ontario Museum. “But after decades of study, we think that these crests functioned primarily as sound resonators and visual exhibits used to communicate within their own kind.”

One of the most recognizable dinosaurs, the duck-shaped Parasaurolophus has an elongated tubular crest on its head with an internal network of airways. Three species of Parasaurolophus are currently recognized, ranging from Alberta to New Mexico in rocks between 77 and 73.5 million years old. The new skull belongs to Parasaurolophus cyrtocristatus, formerly known from one specimen collected in 1923 in the same region of New Mexico by the legendary fossil hunter Charles H. Sternberg. Both specimens exhibit a shorter, more curved crest than other species, a characteristic associated with their immaturity at death.

The partial skull was discovered in 2017 by Smithsonian Ecology Fellow Erin Spear, Ph.D., while exploring the badlands of northwestern New Mexico as part of a Denver Museum of Nature & Science team. Located deep in the Bisti / De-Na-Zin Wilderness of New Mexico, only a small portion of the skull was visible on a steep slope of the sandstone. Museum volunteers led by Sertich were surprised to find the intact crest when they carefully chiseled the monster out of the sandstone. Abundant bone fragments at the site indicated that much of the skeleton could ever be preserved on an old sand bar, but only the partial skull, part of the lower jaw and a handful of ribs survived erosion.

Today, the badlands of northwestern New Mexico are dry and sparsely vegetated, a dramatic contrast to the lush lowlands preserved in their rocks. 75 million years ago, when Parasaurolophus lived in the region, North America was divided into two land masses by a wide seaway. Laramidia, the ribbon of land in the west, stretches from Alaska from today to central Mexico, offering several episodes of mountain building in the early stages of building the present Rocky Mountains. These mountain-building events have helped conserve various dinosaur ecosystems along their eastern flanks, some of the best-preserved and most continuous anywhere on earth. Parasaurolophus shared lush, subtropical floodplains with other, crownless dinosaurs with ducks, a variety of horned dinosaurs and early tyrannosaurs, along with many emerging, modern groups of alligators, turtles and plants.

“The preservation of this new skull is spectacular, and eventually the bones that form the crest of this amazing dinosaur are revealed in detail by almost every dinosaur-obsessed child,” Sertich said. “It only reinforces the importance of protecting our public lands from scientific discovery.”

“My jaw dropped when I first saw the fossil,” Gates said. He continues: “I have been waiting for almost 20 years to see a copy of this quality.”

“This specimen is truly remarkable in its conservation,” said Evans, who has also worked on this iconic dinosaur for nearly two decades. ‘It has answered years of questions about how the crest is built and about the validity of this particular species. This fossil is very exciting to me. ”

The Parasaurolophus pedigree has for decades placed the two long, upright crested species Parasaurolophus (P. walkeri of Alberta and P. tubicen of younger rocks in New Mexico) as the closest relative, despite being separated by more than 1600 kilometers. km) and 2.5 million years. The analysis of additional features of the skull, excluding the crest, together with information from other discoveries of Parasaurolophus from southern Utah, suggests for the first time that all southern species from New Mexico and Utah may be more closely related to their cousin in the north. It fits patterns observed in other dinosaur groups of the same age, including horned dinosaurs.

Reference: “Description and re-diagnosis of the crested hadrosaurid (Ornithopoda) dinosaur Parasaurolophus cyrtocristatus on the basis of new cranial remains ”by Terry A. Gates, David C. Evans and Joseph JW Sertich, January 25, 2021, PeerJ.
DOI: 10.7717 / peerj.10669

The research was funded by the Denver Museum of Nature & Science through generous donations to the Laramidia project. The article describing the new skull of Parasaurolophus appears in the publication of the journal on January 25, 2021 PeerJ.