Ornithomimid Caudal (Tail) Vertebra-Texas 01

Taxa: Indeterminate Ornithomimid

Element: Caudal (Tail) Vertebra

Geology: Aguja formation

Age: Cretaceous-Campanian

Locality: Brewster County, Texas

Ornithomimidae

Ornithomimids, or "ostrich-mimic" dinosaurs, were a group of bipedal theropods belonging to the family Ornithomimidae. They lived during the Cretaceous period and were found in North America, Asia, and possibly other regions. These dinosaurs were characterized by their long legs, lightweight bodies, and toothless beaked skulls, adaptations that suggest they were fast runners. Ornithomimids are thought to have been omnivorous or herbivorous, feeding on plants, small animals, and possibly eggs. Some species, like Ornithomimus, may have had feathers.

Ornithomimids from the Aguja Formation are known from fragmentary remains, indicating the presence of these fast-running theropods in the Late Cretaceous ecosystems of West Texas. Like other ornithomimids, they were likely toothless, long-legged, and built for speed, resembling modern ostriches. Their diet may have included plants, small animals, and possibly eggs. The presence of ornithomimids in the Aguja Formation suggests they inhabited the region’s coastal and floodplain environments, coexisting with hadrosaurs, ceratopsians, and predatory theropods such as dromaeosaurs and tyrannosaurs.

Aguja formation

The Aguja Formation is a Late Cretaceous geological formation in West Texas, primarily exposed in the Big Bend National Park region. It dates to the Campanian stage (approximately 80–72 million years ago) and consists of fluvial, coastal, and deltaic deposits. The formation preserves a diverse fossil record, including dinosaurs such as hadrosaurs, ceratopsians, pachycephalosaurs, tyrannosaurs, and dromaeosaurs, as well as turtles, crocodilians, and early mammals. The Aguja Formation provides important insights into the ecosystems of North America during the Late Cretaceous, showing a rich and varied landscape of rivers, floodplains, and coastal environments.