Mexico, widely recognized for its ancient civilizations, also holds a significant and unfolding paleontological heritage. Beneath its diverse landscapes lie the fossilized remains of dinosaurs, offering a window into a prehistoric past that shaped the North American continent. Recent discoveries continue to reveal the richness of Mexico’s Mesozoic Era, showcasing a variety of dinosaur species that once roamed its ancient plains and coastlines. These finds provide invaluable insights into the distribution and evolution of dinosaurs in the southern reaches of what was once the supercontinent Laramidia.
Major Dinosaur Discoveries in Mexico
Mexico’s fossil record has unveiled a diverse array of dinosaurs, with hadrosaurs, or duck-billed dinosaurs, being among the most extensively represented. Velafrons coahuilensis, a lambeosaurine hadrosaurid, is a notable discovery from Coahuila, characterized by a prominent crest on its forehead. This species, known from a juvenile specimen, suggests an adult length of 9 to 10.5 meters (30 to 35 feet). Another significant hadrosaur find is Coahuilasaurus lipani, an eight-meter-long herbivore also from Coahuila, which was initially misidentified as a Kritosaurus before being reclassified as a distinct species in 2024. From Baja California, the large hadrosaur Magnapaulia laticaudus, originally described as a species of Lambeosaurus, represents one of the biggest duck-billed dinosaurs found in Mexico, measuring up to 12.5 meters (41 feet) long and weighing around 15 tons.
Tyrannosaurs, the apex predators of the Late Cretaceous, also inhabited ancient Mexico. Labocania anomala, known from fragmentary remains including jaw bones, was an early tyrannosaur discovery from Baja California. More recently, Labocania aguillonae was identified from a partial skeleton found in Coahuila, providing evidence of a distinct southern lineage of tyrannosaurs. This new species, at least 6.3 meters (21 feet) long, was lighter-built and long-legged compared to its northern relatives.
Among horned dinosaurs, or ceratopsians, Coahuilaceratops magnacuerna stands out as the first named ceratopsid from Mexico. Discovered in Coahuila, this plant-eater lived approximately 72 million years ago and possessed exceptionally large horns above its eyes, possibly reaching 120 centimeters (47 inches).
Sauropods, the long-necked giants, include Sonorasaurus thompsoni, a brachiosaurid found in southern Arizona. Its name reflects the Sonoran Desert, suggesting its range extended into Mexico.
Armored dinosaurs, specifically nodosaurid ankylosaurs, are also part of Mexico’s prehistoric fauna. Acantholipan gonzalezi is the only formally described thyreophoran from the country. While rarer than hadrosaur finds, their presence in Late Cretaceous sediments of Coahuila and Baja California indicates their distribution in southern North America. Recently, ornithomimids (ostrich-like dinosaurs) gained a new Mexican member with the description of Mexidracon longimanus from Coahuila, characterized by its unusually long hands.
Key Mexican Fossil Sites
Coahuila in northern Mexico is a significant hub for dinosaur discoveries, often called the “mecca of dinosaurs.” Much paleontological work in Coahuila focuses on the Cerro del Pueblo Formation, dating to the Late Campanian age, approximately 73.5 million years ago. This formation has yielded an impressive diversity of dinosaur fossils, including the hadrosaurs Velafrons coahuilensis and Coahuilasaurus lipani, the ceratopsian Coahuilaceratops magnacuerna, and the ornithomimid Mexidracon longimanus. The Sabinas Basin within Coahuila has also provided extensive fossil material.
Baja California also hosts important fossil sites, particularly around the El Rosario region. The El Gallo Formation and Rosario Formation in this area have produced remains of large hadrosaurs, including Magnapaulia laticaudus, and various carnivorous dinosaurs. These formations represent Late Campanian deposits, with some dating to about 73 million years ago. The discoveries in Baja California provide a unique perspective on the dinosaur fauna of the Pacific coastal margin of ancient North America.
Other Mexican states have also contributed to the paleontological record. In Tamaulipas, some of the oldest dinosaur remains in Mexico have been found, dating to the Middle Jurassic period, around 160 million years ago, in the La Boca formation. Oaxaca has provided evidence of Middle Jurassic ankylosaur tracks, known as Tetrapodosaurus, as well as footprints of sauropods and theropods. While less extensively studied than Coahuila and Baja California, states such as Sonora, Chihuahua, Puebla, Chiapas, and Michoacán have also yielded dinosaur bones or indirect evidence like trackways.
Mexico’s Mesozoic Landscape
During the Mesozoic Era, particularly the Late Cretaceous (roughly 85.3 to 72 million years ago), North America’s geography differed vastly from today. A large inland sea, known as the Western Interior Seaway, bisected the continent, creating an island landmass called Laramidia to the west, which included what is now Mexico. This ancient seaway played a significant role in shaping the climate and ecosystems of the region.
Ancient Mexico had a humid, warm climate, supporting lush vegetation and diverse ecosystems. Coastal plains and extensive estuaries were prevalent, with networks of freshwater rivers, brackish swamps, and salty ancient seas providing varied habitats. This tropical forest setting, extending to the coast, supported a wide range of dinosaur species, including large herbivores like ceratopsians and hadrosaurs.
High moisture and warm conditions fostered plant-rich environments, sustaining large herbivore populations. These environmental conditions also contributed to the excellent preservation of dinosaur remains, with many fossils found in sedimentary rocks associated with these ancient water bodies.
Mexico’s unique paleogeography, at Laramidia’s southern margin, fostered distinct faunal assemblages. This suggests dinosaur species in this region were often unique compared to those found further north.