At the end of the Triassic around 199 million years ago, the supercontinent Pangea was just about to break apart and nearly a quarter of all dinosaurs living at the time were wiped out in the planet’s fourth mass extinction event. The fossil record shortly after the Triassic-Jurassic event is pretty incomplete, especially in parts of modern-day South America. Until now, only one dinosaur has ever been found in the northern part of the contient. A new meat-eating dinosaur unearthed in the Venezuelan Andes could help fill in the gaps. It’s dubbed Tachiraptor admirabilis, and it’s described in Royal Society Open Science this week.
Isolated lower leg and pelvis bones from two individuals were unearthed from the earliest Jurassic sediments of the La Quinta Formation in the northernmost extension of the Andes, at the western border of Venezuela. Dating of the zircons in the rocks puts the fossil at 200.7 million years old.
From just these two bones -- specifically the ischium and tibia (pictured) -- a team led by Max Langer from the University of São Paulo was able to determine that it was bipedal, about two meters long, and carnivorous. Tachiraptor belong to the theropod (“beast-footed”) branch of dinosaurs, which led up to modern birds and includes T. rex, velociraptor, a wee pygmy tyrannosaur who stalked the arctic, and the shark-eating spinosaurus, the first ever swimming dinosaur. Unique features of its tibial articulations were different enough from known theropods to warrant a new species.
Tachiraptor is named after Táchira, the Venezuelan state where the fossil was found, and “raptor” (Latin for “thief”), alluding to its predatory habits. The species name references Simon Bolivar's “Admirable Campaign,” where the town La Grita played a strategic role.
Earlier this summer, another team of researchers announced the discovery of the first dinosaur found in northern South America, also from the La Quinta Formation. These fossils were stumbled upon during a highway excavation. The 201-million-year-old Laquintasaura venezuelae likely ate plants and insects, and it belonged to the ornithischians, which go on to include stegosaurus and triceratops later on. And even though it was mostly herbivorous, Laquintasaura looked pretty much like a slightly smaller Tachiraptor. “All the small dinosaurs of that era looked about the same,” University of Birmingham’s Richard Butler tells Science. Butler was part of the team that described Laquintasaura.
In all likelihood, Tachiraptor hunted Laquintasaura. Together, these early Jurassic, mass-extinction survivors will help paleontologists better understand the global rise of dino giants millions of years later. That is, until the Cretaceous extinction event some 130 million years later that dooms all remaining non-avian dinosaurs.
Images: Maurílio Oliveira (top), M.C. Langer et al., Royal Society 2014 (middle)