Dinosaur specimen collected by Cincinnati Museum Center examined by paleontologists

. October 11, 2018

CINCINNATI – A collection of paleontologists from around the world recently published the results of their research shedding light on the development of one of the largest dinosaurs. The research paper, published in Scientific Reports, examined a specimen from the collections of Cincinnati Museum Center (CMC). This small skull is from a sauropod (long-necked herbivorous dinosaur), and the research team believes that it likely belongs to a very young Diplodocus.

At nearly 100-feet long, Diplodocus inhabited the Late Jurassic Period over 150 million years ago and was one of the largest dinosaurs to ever roam the Earth. Over 100 specimens have been recorded since its initial discovery in 1878, making it one of the best-known sauropods. While the skeleton of Diplodocus is well known, cranial remains are exceptionally rare, with only eight known skulls discovered to date. Of those few skulls, the majority are from adults, revealing very little about the growth and development of the skull in the dinosaur. The discovery of a particularly small skull in 2010 helps to fill this missing gap. Paleontologists from Canada, England, Germany and across the United States believe the skull can tell us more about the dinosaur’s maturation and development.

“This skull and the knowledge locked away within it is helping us further understand the intimate details surrounding the life history of these remarkable animals,” says Cary Woodruff, a PhD student working with the Royal Ontario Museum and lead researcher on the paper. “How a baby Diplodocus that hatched from an egg no bigger than a cantaloupe grows up to be 100 feet long within 30 years is astonishing in and of itself – and this skull, like a puzzle piece, is helping us piece together how this rapid growth was even possible.”

The skull, measuring just 24 centimeters long, is the smallest of its kind ever discovered and was unearthed in south central Montana by CMC paleontologist Glenn Storrs, PhD and prepared in the laboratory at the Museum of the Rockies. Diplodocus skulls are remarkably small given the massive size of the dinosaur, but the discovery of a skull less than half the length of known adult cranial remains leads paleontologists to believe it is from a juvenile animal. Upon closer examination, the differences go well beyond size, revealing hitherto unknown aspects of young Diplodocus anatomy and showing that juveniles were not merely smaller versions of adults.

“Analysis of this specimen helps elucidate not only the ontogenetic, or life cycle, trajectory of sauropod dinosaurs such as Diplodocus, but also better resolves their place in the Late Jurassic ecosystem,” says Dr. Storrs, Associate Vice President for Science & Research and Withrow Farny Curator of Vertebrate Paleontology at Cincinnati Museum Center. “It also underscores the vitality of our science, furthering our knowledge of dinosaur paleontology, even after 150 years of intensive study of these remarkable animals.”

Diplodocus is one of at least four sauropods in the Diplodocidae family living together during the Late Jurassic over 150 million years ago in western North America. While Diplodocus and its close kin are very similar, there are distinct differences that distinguish each from the other. Some of those differences can be identified in the skull based on the size and shape of the bones. These features were used to help identify the skull in the research paper as likely belonging to Diplodocus. However, the team notes that since a skull this small have never been found before, and since the skull changes shape through growth, identifying the skull as Diplodocus was not a simple task.

Teeth, too, can be a defining sauropod feature, and it was also the teeth that interested the paleontologists the most with the CMC skull. Whereas adult Diplodocus typically have 10 or 11 teeth, the skull in the paper has 13. Their location, situated in the front of the mouth extending back along the jaw, also differed from mature Diplodocus specimens, where the teeth are located exclusively toward the front of the mouth. Mature Diplodocus teeth are peg-like, long and have narrow crowns. The skull discovered has teeth extending farther back in the jaws, and these back teeth are more spoon-shaped – short and wide with rounded crowns.

The differences in tooth number, shape and location between known mature Diplodocus specimens and the skull in question indicates teeth were lost and their location focused more toward the front of the mouth as they aged. This suggests the diet of the Diplodocus changed as it matured. Overall, the recently-discovered skull presents a maturation life cycle much more complex than a straight line from young juvenile to mature adult.

“From this little skull it would seem that a young Diplodocus took Popeye’s message to heart; if you eat your greens you’ll grow big and strong,” adds Woodruff. “By having different tooth types and a narrow snout it appears that a young Diplodocus could select and chow down on a wider variety of plant types – bulk feeding for its growing body.”

Dr. Storrs is hoping this work will have an impact on the greater public as well. As Cincinnati Museum Center prepares to reopen its museums after a multi-year building restoration, new specimens and the research they inspired may find a home on the gallery floor.

“This is science in action. We’re using data and research to shed light on the previously unknown, to factually reconstruct the prehistoric past” says Dr. Storrs. “Over time these findings will be used to inform other discoveries, fleshing out for us a robust understanding of how these magnificent animals lived millions of years ago. We’re hoping the museum gallery is where guests can watch that research unfold.”

You can read the full text of the research paper titled “The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs” in Scientific Reports online at nature.com/srep. Scientific Reports is a peer-reviewed online, open access, multidisciplinary journal that publishes research from all areas of the natural and clinical sciences.

For more information, visit www.cincymuseum.org

Category: Natural History

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