Paleontologists from the United States and the Slovak Republic have identified and named a new genus and species of hadrosaur dinosaur that roamed what is now New Mexico during the Cretaceous period.
Reconstructing the life of Acisresaurus wimani based on the holotype and related species. Image credit: Sergey Krasovskiy.
“Hadrosauridae“, a family of large herbivorous dinosaurs, were once among the most prevalent dinosaurs in the Late Cretaceous terrestrial ecosystems of the Western Interior Basin of North America for nearly 20 million years,” stated paleontologist Sebastian Dalman from Montana State University, along with colleagues from Harrisburg University, Pennsylvania State University, New Mexico Museum of Natural History, and Pavol Josef Shafarik University.
“Known commonly as ‘duck-billed’ dinosaurs, this group displayed remarkable taxonomic diversity and success during the Cretaceous period.”
“In the final 20 million years of the Cretaceous, hadrosaurids spread across the globe, appearing in Africa, Antarctica, Asia, Europe, and the Americas.”
The newly identified species, Acisresaurus wimani, lived during the late Cretaceous period, roughly 75 million years ago.
Fossilized dinosaur bones were uncovered in the geological formations of the Kirtland Formation, located in the A Si Sle Pa Wilderness, situated between Chaco Canyon and the De Na Gin Wilderness in San Juan County, New Mexico.
“The holotype specimen includes a diagnostically incomplete skull, several isolated cranial elements such as the right zygoma, quadrate, and dentary, along with a series of articulated cervical vertebrae,” the researchers noted.
“Besides the holotype, additional specimens from the same layer could also belong to this newly described species, including a well-preserved left dentary, a partial skeleton, and two humeri—one from a large adult and the other from a juvenile.”
In prior research, Acisresaurus wimani was linked to Kritosaurus, an early genus of saurolophine hadrosaurids found in the Kirtland Formation.
Both species share a close relationship within the subfamily Hadrosaurinae, specifically the Saurolophinae.
However, phylogenetic analyses indicate that they are distinct groups existing during the Campanian period of the Cretaceous in southern Laramidia.
“The younger species, Kritosaurus, belongs to the Critosaurini clade, comprising various species from northern Laramidia,” the scientists explained.
“Furthermore, phylogenetic results indicate the existence of a clade that includes Acisresaurus and Naashoibitosaurus, having diverged from Critosaurini in the late Campanian (75 million years ago), alongside two unnamed species in southern Laramidia.”
According to the research team, Naashoibitosaurus and Acisresaurus represent flat-headed saurolophines that could form a new category of hadrosaurids.
“This clade points to the considerable taxonomic diversity of saurolophines, which were prominent herbivorous dinosaurs in southern Laramidia during the final 20 million years of the Cretaceous,” the authors remarked.
“The discovery of a new hadrosaur species in New Mexico reinforces the evidence of latitudinal variation in hadrosaur faunas across Laramidia during the Late Cretaceous.”
The team’s study will be published in the Bulletin of the New Mexico Museum of Natural History and Science.
_____
Sebastian Dalman et al. 2025. A new saurolophine hadrosaurid (Ornithischian: Hadrosauridae) discovered in the Late Cretaceous (Campanian) Hunter Wash Member, Kirtland Formation, San Juan Basin, New Mexico. Bulletin of the New Mexico Museum of Natural History and Science 101
Source: www.sci.news
