Meraxes

MEANING: Meraxes

PERIOD: Late Cretaceous

CONTINENT: South America

Meraxes is a very large carcharodontosaurid theropod dinosaur, at about 10 m in length, and weighing approximately 4.5 t. Analysis of the holotype specimen suggests it could have been up to 53 years old when it died, having reached skeletal maturity 4 years prior to its death. This would make it the longest-lived non-avian theropod currently known.

Meraxes is from the Late Cretaceous. The Cretaceous is the third and final geological period of the Mesozoic Era, with the Late Cretaceous making up roughly the second half of it, lasting from about 100 to 66 million years ago. It was a time of significant evolutionary change, with dinosaurs reaching their greatest diversity before the mass extinction at the end of the Cretaceous.

The Cretaceous was a period with a relatively warm climate, though the Late Cretaceous experienced a global cooling trend, caused by falling levels of carbon dioxide in the atmosphere. The continents were nearing their present positions, but high sea levels flooded low-lying regions, turning Europe into an archipelago, and forming the Western Interior Seaway in North America. These seas were home to a variety of marine reptiles, including mosasaurs and plesiosaurs, while pterosaurs and birds shared the skies.

On land, dinosaurs continued to thrive and diversify during the Late Cretaceous, producing many of the most well-known groups, including tyrannosaurs, hadrosaurs, and pachycephalosaurs. Established Cretaceous dinosaur clades like the ceratopsians, ankylosaurs, and dromaeosaurs continued to flourish. Sauropod species consisted almost exclusively of titanosaurs, which seemed to be confined to the Southern Hemisphere for much of the Late Cretaceous. Flowering plants and grasses diversified and spread, becoming the dominant flora similar to what we see today.

The Cretaceous (along with the Mesozoic) ended with the Cretaceous-Paleogene (K-Pg) extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. This event, likely triggered by an asteroid impact, is marked by the abrupt K-Pg boundary, a distinct geologic layer separating the Mesozoic and Cenozoic Eras. In its aftermath, mammals and avian dinosaurs rapidly diversified, becoming the dominant land animals of the Cenozoic Era.

Meraxes is a carcharodontosaur. Carcharodontosauria is a group of large-bodied theropod dinosaurs known for their massive size, elongated skulls, and blade-like, serrated teeth. These predators appeared in the Late Jurassic and thrived through most of the Cretaceous period, often serving as apex predators in their ecosystems. Their skulls were typically long and low, housing powerful jaws lined with sharp, recurved teeth suited for slicing through flesh. They are sometimes thought to have been adapted specifically for hunting sauropods.

Carcharodontosaurs were widely distributed across what are now South America, Africa, Europe, and Asia. Their success across such a broad geographic range suggests they were highly adaptable hunters. By the Late Cretaceous, however, their diversity declined, and they eventually vanished from the fossil record, likely displaced by other emerging theropod lineages. Nonetheless, they represent an important chapter in the history of predatory dinosaurs, illustrating the rise and fall of a group that once dominated much of the prehistoric world.