biologyScience

A new dinosaur skull with a tubular crest reveals a strange crest evolution

Credit: Copyright Doug Shore, Denver Museum of Nature and Science.

Discovery Brief:

The first new skull of a rare species of dinosaur Parasaurolophus (identified by the large hollow tube growing on its head) was discovered 97 years ago.

The remarkable preservation of the new skull gives paleontologists the first opportunity to know definitively how such a strange structure grew on this dinosaur.

For the first time, this study found properties to link the tubular-crested dinosaur species found in southern North America (New Mexico, Utah), which differ from the single northern species (Alberta).

The region in northwest New Mexico dates back to about 75 million years ago, a time when North America was divided by a shallow sea and teeming with duck-billed dinosaurs, horned dinosaurs, and early tyrannosaurs.

Excavations from the area are part of the natural heritage of the Diné (Navajo Nation) and Puebloan peoples. The new Parasaurolophus fossil, from the Northwest New Mexico Wildlands Administration Office, stresses the importance of protecting public lands as natural laboratories and repositories for scientific discoveries.

Jan 25 – Denver – The first new skull discovered in nearly a century from a rare species of the iconic dinosaur Parasaurolophus was announced in the magazine today. Berg. The exquisite preservation of the skull, and especially the oddly shaped nasal passage, has finally revealed the structure of the crest after decades of disagreement.

Despite the highly conformation of the specimen, the sample details show that the crest is shaped much like the tops of other duck-billed dinosaurs. “This specimen is a wonderful example of amazing creatures that arose from a single ancestor,” said Joe Search, curator of dinosaurs at the Denver Museum of Nature and Science and head of the team that discovered the sample.

Imagine your nose growing across your face, three feet behind your head, and then turning around to hang over your eyes. “Parasaurolophus was breathing through eight feet of tubes before oxygen reached its head,” said Terry Gates, a paleontologist from North Carolina State University.

“Over the past 100 years, ideas about the exaggerated tube logo have ranged from diving to super sniffers,” noted David Evans, Temerty’s chief vertebrate palaeontologist and vice president of natural history at the Royal Ontario Museum. “But after decades of study, we now think that these signs functioned primarily as audio resonances and visual displays used to communicate within their own species.”

Among the most famous dinosaurs, Parasaurolophus had an oblong tube-like crest on its head that contained an internal network of bronchi. Three species of Parasaurolophus are currently recognized, ranging from Alberta to New Mexico in rocks dating between 77 and 73.5 million years ago. The new skull belonged to Parasaurolophus cyrtocristatus, previously known from a single specimen collected in the same area of ​​New Mexico in 1923 by the legendary paleontologist Charles H. Sternberg. Both specimens display a shorter and more curved crest than the other species, a feature that may be related to their immaturity at death.

The partial skull was discovered in 2017 by a Smithsonian fellow ecologist, Irene Speer, Ph.D., while exploring the badlands of northwest New Mexico as part of the Denver Museum of Nature and Science team. Located in the depths of Piesti / De Na-Zen Wild in New Mexico, only a small portion of the skull was visible on a steep slope of sandstone. Museum volunteers led by Sertich were surprised to find the intact summit as they carefully excavated the sample from the sandstone. The abundant bone fragments at the site indicated that much of the skeleton may have been preserved at one time on an ancient sand bar, but only the partial skull, part of the lower jaw, and a handful of ribs survived wear.

Today, the badlands of northwest New Mexico are dry and sparse with vegetation, a stark contrast to the fertile lowland floodplains preserved in its rocks. 75 million years ago, when Parasaurolophus lived in the region, North America was divided into two land masses by a broad sea route. Laramidia, the strip of land to the west, extended from today’s Alaska to central Mexico, and hosted multiple episodes of mountain building in the early stages of building the Rocky Mountains today. These mountain-building events have helped preserve the diverse dinosaur ecosystems along their eastern sides, some of them among the best preserved and most enduring systems anywhere on Earth. Parasaurolophus shared fertile subtropical floodplains with other duck-billed dinosaurs, a variety of horned dinosaurs, and early tyrannosaurs along with many emerging modern groups of crocodiles, turtles, and plants.

“The preservation of this new skull is amazing,” said Search. “He finally revealed in detail the bones that make up the crest of this amazing dinosaur that almost every child is obsessed with with dinosaurs.” “This only reinforces the importance of protecting our public lands for scientific discoveries.”

“My jaw fell when I first saw the fossil,” Gates said. He continued: “I have been waiting for nearly 20 years to see a sample of this quality.”

“This specimen is really great to be preserved,” said Evans, who has also worked on this iconic dinosaur for nearly two decades. “It answered long-standing questions about how the summit was built and about the health of this particular species. To me, this fossil is very interesting.”

For decades, the Parasaurolophus family tree has placed the Parasaurolophus species (P. walkeri of Alberta and P. tubicen of younger rocks in New Mexico) as more closely related despite being separated by more than 1,000 miles (1,600 km) and 2.5 million years. Analysis of additional features of the skull except for the summit, along with information from other Parasaurolophus discoveries from southern Utah, suggests for the first time that all southern species from New Mexico and Utah may be more closely related than their northern cousin. This fits the patterns observed in other dinosaur groups of the same age, including the horned dinosaurs.

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The research was funded by the Denver Museum of Nature and Science through generous donations to the Laramidia Project. The paper describing the new skull of Parasaurolophus appears on the January 25, 2021, issue of the journal Berg.

About the Denver Museum of Nature and Science

The Denver Museum of Nature and Science is the Rocky Mountains region’s leading resource for informal science education. Our mission is to be a catalyst and ignite the community’s passion for nature and science. The museum envisions an empowered community that loves, understands, and protects our natural world. A variety of engaging exhibits, discussions, and activities help museum visitors to celebrate and understand the wonders of Colorado, the Earth, and the universe. The museum is located at 2001 Colorado Blvd., Denver, CO, 80205. To find out more about the museum, visit dmns.org or call 303.370.6000. The museum’s many educational programs and exhibitions are made possible in part by the citizens of the seven-county metro area through the Scientific and Cultural Facilities District (SCFD). The museum is accredited by the American Alliance of Museums. Connect with the museum on Facebook, Twitter, and Instagram.

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