In March 2007, Mexican paleontologist Martha Carolina Aguilón made a unique discovery. Among the rocks of Cerro del Pueblo, a geological formation in the south of the state of Coahuila, the expert found the remains of a small skull; A “mystery piece” that doesn’t match any dinosaurs identified in the area. Sixteen years and dozens of analyzes later, the fossil revealed that 74 million years ago, the troodontids, a group of carnivorous dinosaurs with the largest brain capacity of any species, lived in Mexico. The discovery not only adds to the diversity of dinosaurs found in Coahuila — a state that, until three decades ago, made efforts to unearth a legacy unseen until the Desert Museum serves as the nation’s most relevant dinosaur research and dissemination center — but also to the geological puzzle that seeks to paint a picture of the world just before the extinction event that ended the age of dinosaurs. It provides a new part.
“Since the dinosaur we found was small and medium-sized, its bones must have been very fragile,” Aguillon explains to EL PAÍS, noting the improbability of the discovery. The remains of the troodontid’s skull, which includes the frontal and parietal bones, fought against time before being discovered, avoiding all manner of obstructions and being crushed by millions of years of earthquakes since being destroyed by scavengers. “Because they’re so small, they’re hard to find once they become fossilized, and even harder to identify if you find them. That’s what makes this discovery so important,” says the man responsible for the latest discovery in a series of extinct giants that in recent decades, thanks to a campaign by the state government, elevated Coahuila to the “land of the dinosaurs.”
About 74 million years ago, the panorama of southern Coahuila was very different. Instead of the arid climate and semi-desert landscape that prevails in the region today, dense subtropical vegetation moved through swamps and lagoons to the shores of the ancient Tethys Sea. This warm and humid environment encouraged the appearance of large herbivores. At 4.3 feet tall and more than eight feet long, the dinosaur, with its body covered in feathers, did not reach the size of the larger tyrannosaurids that also lived in northern Mexico. However, it had a unique trait that has been a controversial subject of study for paleontologists for decades: a larger brain capacity than any other dinosaur.
“Since the 1970s, they began to think that this dinosaur was the most intelligent because of the size of its skull, which indicates a large brain capacity relative to its dimensions compared to, for example, Tyrannosaurus rex, measured 40 feet but had a 12-inch brain. Intelligence is subjective, but it is the dinosaur with the largest brain relative to its body,” explains Hector Rivera Silva, head of the Department of Paleontology at the Desert Museum. Remains of the skull reveal that it had highly developed vision, with large, forward-positioned eyes, as well as a keen sense of smell, characteristics that have led experts to speculate about its nocturnal habits. “This dinosaur must have gone after smaller prey such as snakes, mammals, lizards, as well as baby dinosaurs found in the same geological formations. “We knew it had a specific ecological role because it was the predator that was missing,” says Aguillon.
A group of paleosculptors advised by Aguillon and Rivera, the dinosaur, which belongs to the troodontid family and whose species has not yet been determined, will be recreated as a complete specimen and displayed at the Desert Museum, where it has been kept for 23 years. Including the most important paleontological discoveries in Mexico velafrons coahuilensis, a six-ton, 23-foot-long herbivore, rose to fame after becoming the first named dinosaur in Coahuila and the most complete ever found in Mexico. The discovery, made in April 1995 by a team led by Martha Carolina Aguilon, was key to the state’s paleontology boom, which brought unprecedented government investment and international scientific cooperation, opening the door to the identification of dinosaurs in the country. “We might say harshly that we’re taking our first baby steps, or we might get excited and claim to be at the forefront of this kind of learning. While Coahuila completes the book of life in the history of dinosaurs and other species, we are still in the inventory stage to find out what we have,” Aguillon concludes.
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