Anchisaurus

Chapter • Meet the dinosaur

Overview

Anchisaurus was a small, lightly built plant-eater with a long neck, a comparatively tiny head and a slender tail carried horizontally as a counterbalance. At roughly 2–2.5 metres long and 20–40 kilograms, it ranks among the smallest known sauropodomorphs — the lineage that would eventually produce giants such as Brachiosaurus. Its hind limbs were noticeably longer and stronger than the forelimbs, and each hand carried a large, curved thumb claw. Its skin was almost certainly scaly; no evidence for feathers exists in early sauropodomorphs. The skeleton suggests an animal that could switch between walking on all fours and rearing up on its hind legs. The wrists were twisted so that the palms faced inwards rather than downwards, which makes sustained four-legged running unlikely; the hand looks as much like a grasping, raking and defensive tool as a weight-bearing foot. Anchisaurus probably browsed low vegetation but could stand up to reach higher foliage, using the long tail for balance. Its teeth were spatula-shaped with coarse serrations along the edges — a classic herbivore tooth suited to snipping soft leaves, ferns and conifer shoots. Because those teeth could not chew, the plant material was likely swallowed whole and fermented in a large gut. Some researchers have argued that early sauropodomorphs like Anchisaurus occasionally ate insects or carrion, but the evidence is thin and most workers today treat it as a committed herbivore. Anchisaurus holds a special place in scientific history. Bones from the Connecticut Valley of Massachusetts and Connecticut are among the very first dinosaur remains found in North America. Fragments blasted from rock at Windsor, Connecticut in 1818 were originally taken for human bones. In 1855 Edward Hitchcock described a skeleton from a sandstone quarry at the Springfield Armory as Megadactylus polyzelus; that name was already occupied, and in 1885 Othniel Charles Marsh coined the name we use today, Anchisaurus, meaning "near lizard".

Chapter • Where it lived

Habitat

Anchisaurus lived about 200–190 million years ago, in the Early Jurassic, in what is now New England in the United States. Its fossils come from the Portland Formation of the Connecticut Valley, especially from Springfield, Massachusetts, and sites in Connecticut. Back then the region sat in a long rift valley formed as the supercontinent Pangaea began to tear apart. The landscape was one of broad floodplains, seasonal lakes and open woodlands of conifers, cycads and ferns, under a warm climate with pronounced wet and dry seasons. The same rocks are famous for thousands of dinosaur footprints, showing a valley busy with both herbivores and predators.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy