Chindesaurus

Chapter • Meet the dinosaur

Overview

Chindesaurus was a small to medium-sized bipedal predatory dinosaur from the closing chapters of the Triassic. It reached roughly two to three metres in length, much of that made up by a long, stiffened tail, and probably weighed only ten to forty kilograms. The body was carried horizontally over the hips with the tail acting as a counterweight, so no part of the tail dragged along the ground. The hind limbs were long and slender, and the pelvis had the simple, primitive construction typical of the very earliest dinosaurs. No feather impressions are known from Chindesaurus or its close relatives, so reconstructions usually show scaly skin, although simple filament-like body coverings cannot be ruled out in dinosaurs this early. Most of what we can say about the animal's lifestyle is inferred from skeletal anatomy and from the environments in which the fossils were buried. The lightly built skeleton and long hind legs point to a fast-moving hunter that ran down smaller prey. The forelimbs were shorter than the hind limbs and ended in grasping hands with curved claws. Because only parts of the skeleton are preserved — and the skull is essentially missing — a great deal about its behaviour remains genuinely unknown, and researchers are careful not to over-interpret the material. Chindesaurus was a carnivore. It lived in an ecosystem dominated by large crocodile-line archosaurs such as rauisuchians and phytosaurs, alongside big temnospondyl amphibians, while dinosaurs were still small and comparatively rare members of the fauna. Its prey most likely consisted of small reptiles, early mammal relatives, amphibians and possibly carrion. The first skeleton was found in 1984 by fossil collector Bryan Small in the Chinle Formation of Petrified Forest National Park, Arizona, USA. The specimen was nicknamed "Gertie" after the animated film dinosaur, and it attracted considerable attention because it was thought at the time to be one of the oldest dinosaurs ever found. The animal was not formally described and named until 1995, by Robert Long and Phillip Murry. The genus name refers to Chinde Point in the national park, while the species name bryansmalli honours its discoverer. Additional material has since been referred to the genus, including specimens from the Hayden Quarry at Ghost Ranch, New Mexico. Where Chindesaurus belongs on the dinosaur family tree has been debated for decades: it has been placed both as an early theropod and, in several more recent analyses, within the family Herrerasauridae.

Chapter • Where it lived

Habitat

Chindesaurus lived during the Late Triassic (Norian, roughly 223–213 million years ago) in what is now the southwestern United States. Its fossils come from the Chinle Formation, above all from Petrified Forest National Park in Arizona where the holotype was collected, and from localities such as the Hayden Quarry at Ghost Ranch in New Mexico. The landscape was one of broad floodplains crossed by meandering rivers, with strongly seasonal rainfall and forests of conifers and tree ferns — the very trees whose trunks now lie petrified across the park. All the continents were then joined in the supercontinent Pangaea, and the region sat much closer to the equator than it does today.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy