A newly identified duck-billed dinosaur has been discovered in northern New Mexico, shedding light on a species previously unknown to science. This dinosaur, named Ahshislesaurus wimani, lived around 75 million years ago during the late Cretaceous period. At that time, the area was a warm coastal plain crisscrossed by rivers.
The fossils were first unearthed in 1916 but were incorrectly categorized for many years. A fresh analysis has revealed that these bones belong to an entirely new species. The lead researcher, Spencer G. Lucas from the New Mexico Museum of Natural History and Science, collaborated with experts from the U.S. and Slovakia to classify this dinosaur.
Ahshislesaurus is part of the Hadrosauridae family, known for their distinct, plant-eating habits. Unlike other members of this family, this dinosaur did not have a tall crest on its head. Instead, it featured a flat skull profile. Estimates suggest it was more than 35 feet long and weighed about nine tons. Lucas expressed excitement about this discovery, noting that many more dinosaur species remain to be discovered.
The fossils came from the Ah-shi-sle-pah Wilderness. Initially classified under the name Kritosaurus navajovius, the bones were re-examined to establish their true identity.
Importance of Ahshislesaurus
Hadrosaurs were some of the most common large herbivores in North America during the late Cretaceous. They thrived in river deltas and floodplains, occupying these areas for about 20 million years. The identification of Ahshislesaurus enhances our understanding of dinosaur diversity in western North America and suggests that ancient geographical barriers shaped their evolution.
Interestingly, this region has yielded many important late Cretaceous fossils, and discoveries from New Mexico often fill gaps left by better-studied areas in Montana and Alberta.
Discovering the Details
The research team compared the skull of Ahshislesaurus with similar dinosaurs. By analyzing traits and building a family tree, they found that it is closely related to Naashoibitosaurus, another dinosaur from the area. They conducted both Bayesian and parsimony analyses, leading to a consensus on the placement of the new species in the hadrosaur family tree.
Distinct features of Ahshislesaurus include a strong cheek region and a uniquely shaped lower jaw. The main fossil specimen includes an incomplete skull, jaw elements, and several neck vertebrae.
Ecosystem during the Late Cretaceous
Living around rivers, Ahshislesaurus shared its habitat with armored ankylosaurs and horned dinosaurs like Navajoceratops. Predators, including relatives of tyrannosaurs, prowled the channels in search of prey. During this time, the region was part of Laramidia, a landmass divided by a shallow sea, which helped isolate dinosaur populations.
The flora of the time would have included conifers and flowering plants, providing plenty of food for these massive herbivores.
What the Name Represents
The name Ahshislesaurus pays tribute to the Ah-shi-sle-pah landscape where the fossils were found. The species name wimani honors Carl Wiman, a pioneer in studying fossils from the San Juan Basin.
Broader Implications
This discovery enriches our understanding of hadrosaur diversity in Laramidia. Ahshislesaurus and Naashoibitosaurus highlight a flat-headed branch of hadrosaurs that coexisted with others featuring more elaborate headgear. Recent studies on these varied structures, including those of Parasaurolophus, show that hadrosaurs diversified not just in head shape but also in their jaws and teeth, indicating differences in diet and habitat needs.
As more museum collections are analyzed, viewers can expect new names and updated classifications, leading to an ever-evolving understanding of these fascinating creatures.
For further reading on this research, check out the findings published in the New Mexico Museum of Natural History and Science Bulletin 101.
