Torvosaurus

Chapter • Meet the dinosaur

Overview

Torvosaurus tanneri was one of the largest predators of the Late Jurassic and a heavily built cousin of Europe's Megalosaurus. It reached roughly 9–11 metres in length, carried its head about three metres above the ground and, according to most published estimates, weighed somewhere between two and five tonnes. The skull was tall and narrow, probably a little over a metre long, and the jaws held robust, serrated teeth; the front teeth were exceptionally long when the root is included. Unlike many later large theropods, Torvosaurus had short but extraordinarily muscular arms tipped with big curved claws — its humerus is among the stoutest known for any theropod. The body was held horizontally and balanced by a straight, stiffened tail that never dragged on the ground. Most of what we infer about its behaviour comes from comparisons with relatives and from the animals found in the same beds. Torvosaurus was probably an ambush hunter that used the power of its neck and shoulders to hold prey while the jaws did the damage. Those short, immensely strong forelimbs suggest that the claws played a real role in gripping, a different approach from the contemporary Allosaurus, which was more lightly built with longer legs. The coexistence of two such large predators implies they targeted different prey or different parts of the landscape. Whether Torvosaurus bore any feather-like covering is unknown: no skin impressions are preserved for the genus and no feathers are known from megalosauroids, so most reconstructions show scaly or naked skin, with sparse filaments treated only as a possibility. Its diet was entirely meat. The Morrison Formation ecosystem supplied juvenile sauropods such as Apatosaurus, Diplodocus and Camarasaurus, plated Stegosaurus, and smaller plant-eaters like Dryosaurus and Camptosaurus. Torvosaurus almost certainly took both live prey and carcasses; bite marks on Morrison bones show that large predators regularly fed right down to the bone. The first bones were found in 1971 by Vivian and Daniel Jones at the Dry Mesa Quarry in western Colorado. Peter Galton and James Jensen described and named the species in 1979; the genus name means roughly "savage lizard" and the species name honours Nathan Eldon Tanner. More material has since turned up in Morrison rocks in Colorado, Utah and Wyoming. A second species, Torvosaurus gurneyi, was named in 2014 from Portugal, showing that closely related giants lived on both sides of the young Atlantic.

Chapter • Where it lived

Habitat

Torvosaurus tanneri lived roughly 153–148 million years ago, in the Late Jurassic, across the broad plains and floodplains of what is now the western United States. The Morrison Formation preserves a semi-arid landscape with strong seasonal rains, meandering rivers, temporary lakes and gallery woodland of conifers, ginkgoes and tree ferns along the watercourses. Fossils come mainly from the Dry Mesa Quarry in Colorado, with additional material from Utah and Wyoming.

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy