Ancient Ostrich Terror Birds Left 8M-Year-Old Tracks on Fossil Substrate in Argentina

A team of paleontologists in Argentina found 8 million-year-old tracks on a fossilized substrate made by "terror birds," ancient ostrich-like creatures that are taller than humans.

Terror Birds in Argentina

In collaboration with a colleague from LA TE Andes SA, a group of paleontologists from Universidad Nacional de La Pampa discovered the first Phorusrhacidae footprints ever discovered in good condition in Argentina. The team's paper details the location of the prints' discovery, their state, and the lessons they have drawn from them.

During the Cenozoic, a family of ostrich-like birds known as the Phorusrhacidae-commonly known as "terror birds," lived in South America; there is also evidence that some species may have also existed in North America and Africa. They had long legs and powerful beaks, and they were flightless birds. They caught their prey by pursuing it and either beak-chopping it or claw-slicing it.

Tracks From Ancient Ostrich-Like Birds

The birds were 1-2 meters tall, according to fossil discoveries. In addition, they possessed small bodies; the largest birds may weigh up to 70 kg. The research team discovered the first specimen of Phorusrhacidae footprints that had been preserved in this new project.

A medium-sized Phorusrhacidae, most likely belonging to the Mesembriornithinae subfamily, formed the prints. They were discovered by the researchers in a narrow waterway near to shore at a coastal outcrop on the San Matas Gulf. According to testing of the fossil substrate, the traces were created some 8 million years ago.

The scientists discovered that they displayed cross-cutting-related wave ripples and wrinkle traces. Mud cracks may be seen at the tracks' edges. According to the experts, the traces were formed when the bird flew through a mudflat away from the coast. The scientists estimate that it was running at a rate of 2.74 m/s and had a hip height of 0.81 m. The thickness of the traces revealed that the bird weighed an average of 55 kg.

8 Million Years Ago

Around 8 million years ago, Argentina's plains were the home of energetic, towering figures-feathery creatures that stood taller than man. With formidable hooked beaks as colossal as a horse's head, these were the dread-inducing terror birds, the apex predators of their era. Among the exclusive clan of carnivorous flightless birds, they embodied the raw might and savagery reminiscent of their dinosaur ancestors.

They birds reigned supreme in South America, holding dominion over a realm teeming with early herbivorous mammals and relatively diminutive carnivores.

Throughout Earth's prehistory, various avian lineages assumed the roles of flightless herbivores. Modern ratites like emus, ostriches, and cassowaries represent one such lineage, while numerous waterfowl families thrived as robust terrestrial browsers across the globe. Intriguingly, terror birds share a genetic kinship with the modern seriema, a relative of parrots, falcons, and passerines, bridging their evolutionary connections.

Recent genetic evidence underscores these relationships, illuminating the intricate tapestry of Earth's evolutionary history.