Description and Classification

Latirhinus was a large, plant-eating dinosaur, estimated to have reached lengths of around 8 meters (about 26 feet). Like other hadrosaurs, it had a flattened, duck-like beak for cropping plants and hundreds of tightly packed teeth in its cheeks, forming dental batteries. These teeth were excellent for grinding tough vegetation. Latirhinus could likely walk on both two legs (bipedally) for running and four legs (quadrupedally), perhaps when grazing.

The most noticeable feature of Latirhinus was its snout. It possessed a broad, arched nasal bone that formed a prominent bump or arch on top of its nose. This was a solid bone structure, unlike the hollow crests seen in some other hadrosaurs like Parasaurolophus. This wide nasal arch is what gives Latirhinus its name and helps distinguish it from its relatives.

Latirhinus belongs to the family Hadrosauridae, specifically within the subfamily Saurolophinae. Saurolophines are often called “solid-crested” or “non-crested” hadrosaurs, although some, like Latirhinus, did have bony nasal structures. More precisely, Latirhinus is classified as a “kritosaurin,” a group of saurolophines that includes dinosaurs like Kritosaurus and Gryposaurus, which also had distinctive nasal features.

Distinguishing Features

Latirhinus had several features that set it apart from other hadrosaurs, especially its close relatives:

• A very broad and significantly arched nasal bone, creating a wide, convex (outwardly curved) bump on the upper part of its snout.
• This nasal arch was relatively long and wide compared to the narrower nasal crests or hooks found in dinosaurs like Gryposaurus.
• The exact shape of its nasal arch distinguished it from the incompletely known nasal structure of Kritosaurus.
• It possessed a relatively elongated snout.

Paleoenvironment and Diet

Latirhinus lived in what is now the Cerro del Pueblo Formation in Coahuila, Mexico. During the Late Cretaceous, this area was a coastal plain with rivers, deltas, and estuaries, bordering a large inland sea. The climate was warm and humid. This environment supported a diverse ecosystem.

Latirhinus shared its habitat with a variety of other dinosaurs. These included other hadrosaurs like Velafrons, horned dinosaurs such as Coahuilaceratops, large meat-eaters like tyrannosaurids, armored ankylosaurs, as well as pterosaurs, crocodiles, and turtles. As a herbivore, Latirhinus would have fed on the abundant plant life, likely including conifers, cycads, and early flowering plants. Its strong beak and dental batteries were well-suited for processing tough plant material, probably browsing on vegetation at low to medium heights.

Significance and Ongoing Research

The discovery of Latirhinus is important because it adds to our understanding of hadrosaur diversity, particularly in the southern part of North America (Laramidia) during the Late Cretaceous. It highlights that Mexico had its own unique set of dinosaur species. The distinct nasal structure of Latirhinus provides valuable information about the evolution and variety of head ornamentation in saurolophine hadrosaurs.

The function of its broad nasal arch is a topic of interest. While it was a solid structure, it could have been used for display, helping individuals recognize members of their own species or attract mates. It might also have been involved in pushing contests or other social behaviors, though this is speculative. Ongoing research includes further analysis of its fossils to refine its place within the Kritosaurini group and to better understand its relationship with dinosaurs like Kritosaurus and Naashoibitosaurus. Future discoveries of more complete Latirhinus skeletons would greatly help paleontologists learn more about its anatomy, behavior, and the role it played in its ancient ecosystem.