Malinzak also credited the discovery as additional evidence supporting the history of dinosaur migration throughout North America and taxonomic exchange between North and South America — the new species is part of a larger group that spread north from New Mexico and into Canada, as well as through Central America into South America. The dinosaur diversity could also provide information about the ecosystems in which they lived, further informing theories about what ultimately caused their extinction, he said.
“What we’re noticing is the Southwest is a ‘stock’ for some animals that migrate to the North,” Malinzak said. “We’re seeing changes environmentally. It seems that at a few different times, groups of organisms from the southern part of the continent migrated northward. During one of these events, the ancestors of the new hadrosaur migrated north, replacing another hadrosaur group, while others also spread into South America. Later, as new forms migrated to North America from Asia, the descendants of the earlier migrants returned to the southern part of the continent where descendants of the older lineage continued to thrive. The lineages appear to have co-existed in the region for a time. It showed that this group not only exploded with diversity across the continent at one point, but also contributed to the world-wide spread of this group in the Late Cretaceous.”
He explained that although Ahshiselsaurus wimani was previously misidentified as a specimen of Kritosaurus, the species actually appears stratigraphically lower than Kritosaurus, meaning it appears deeper in the rock layers and suggests it is older. The finding indicated that the Southwest’s climate was an ideal ecosystem for various groups of dinosaurs, Malinzak said.
“The ecosystem was more diverse than initially considered,” Malinzak said. “It supports the idea that the environment you’re in drives your adaptation. If a new group is well-adapted to an environment it migrates to, it can ‘unseat’ existing species — if the territory has undergone environmental change and the ‘home team’ has yet to adapt.”
Malinzak incorporated methods from the study into his Lehigh Valley “BIOL 220W: Populations and Communities” course to give his students the opportunity to apply their knowledge to real research.
“I was able to show my students what information our team used, how we ran the calculations, and how we were able to determine dispersal and divergence events,” he said. “The method helped the students take the idea of studying relationships from a theoretical idea to a tangible process to follow.”
Aníbal Torres, chief academic officer at Penn State Lehigh Valley, praised the depth of expertise reflected in this work.
“Dr. Malinzak brings exceptional passion and commitment to his field,” he said. “That dedication consistently drives meaningful and high-quality scholarship.”
Next, Malinzak said the team will continue studying the newly identified species, along with other fossil specimens discovered in the Southwest.
“This discovery reveals that we should revisit some of the specimens of other animals previously collected in this area,” Malinzak said. “We’re examining how evolutionary relationships are shaping the pictures of these animals and trying to make sense of how these relationships came to be, along with the ecological pressures that drove them. New discoveries and information help us answer current questions, but they also help us to pose new questions as well. Our present work is not the end result. — It’s more like, ‘You made one lap, but there are more laps still to go in the race.’ We’re making progress.”
Co-authors on the study include Sebastian Dalman, Montana State University; Steven Jasinski, Harrisburg University; Spencer G. Lucas and Anthony R. Fiorillo, New Mexico Museum of Natural History; and Martin Kundrát, Pavol Jozef Šafárik University in Slovak Republic.
The Slovak Research and Development Agency, and the Ministry of Education, Research, Development and Youth of the Slovak Republic supported this work. Financial support was also provided by the New Mexico Museum of Natural History.