There's a new dinosaur species on the block. An international team, including a biologist from Penn State Lehigh Valley, discovered that a 75-million-year-old fossil classified as a different dinosaur is its own massive, duck-billed species. Working with the New Mexico Museum of Natural History & Science, the team named the newly identified species Ahshiselsaurus wimani as a nod to the area in which it was originally found in 1916.
D. Edward Malinzak, assistant teaching professor of biology at Penn State Lehigh Valley since 2021, and the team published their findings in the Bulletin of the New Mexico Museum of Natural History and Science. The revelations came after a new analysis of fossils found in New Mexico.
The newly identified species is part of the herbivorous duck-billed hadrosaurid family that includes numerous other species. The team conducted an anatomical and morphological comparison of the specimens against other fossils in the hadrosaurid genera and species to make this determination.
"Hadrosauridae, a family of large herbivorous dinosaurs, were among the most abundant dinosaurs of Late Cretaceous terrestrial ecosystems of the Western Interior Basin of North America for about 20 million years," said Sebastian Dalman, a paleontologist at Montana State University and lead author on the study. "The holotype specimen consists of an incomplete diagnostic skull, several isolated cranial elements including the right jugal, quadrate, dentary and surangular, and a series of articulated cervical vertebrae."
A holotype specimen refers to the fossil or collection of fossil pieces used to officially categorize a new species. Ahshiselsaurus wimani was originally classified in 1935 as a specimen of the hadrosaurid genus Kritosaurus, which Malinzak said now, 90 years later, appears to be incorrect.
"Kritosaurus is still a valid genus with species of its own," Malinzak said. "We took a specimen that was lumped in as an individual of Kritosaurus and determined it had significantly distinct anatomical features to warrant being its own genus and species."
The researchers more closely examined the bones of the specimen now named Ahshiselsaurus wimani and compared them with bones of other hadrosaurid specimens. They also used the physical characteristics of the fossils to conduct a phylogenetic analysis, a method that uses available data to predict evolutionary relationships among species.
"As a general rule … skulls are really the basis for identifying differences in animals," said Anthony Fiorillo, co-author, and executive director of the New Mexico Museum of Natural History and Science. "When you have a skull and you're noticing differences, that carries more weight than, say, you found a toe bone that looks different from that toe bone."
