It’s often a great distinction to be first at anything, and Anchisaurus (meaning “near lizard”) had the distinction of being the first dinosaur discovered in North America. In 1818, while sandstone in Connecticut was being quarried for building material, a small skeleton of Anchisaurus was discovered. Because of its diminutive size of 6.6 feet long, 3 feet tall and a weight of 60 pounds, its remains were mistaken for human bones. When further fossil discoveries were made in Massachusetts, and the bones began accumulating, they were initially identified as reptilian. Anchisaurus was not fully recognized as a dinosaur until 1885.
Living during the Early Jurassic Period, 188 to 200 million years ago, Anchisaurus was an early herbivorous dinosaur, or plant eater. Because it looked very primitive, it was classified as a prosauropod, meaning “before the lizard-footed,” and belonged among the earliest dinosaurs of its lineage. Small in comparison to its later earth-shudderingly gargantuan sauropod relatives such as Brachiosaurus and Apatosaurus, Anchisaurus was sizeable for this initial period of the dinosaurs. It had a long neck, an unusually small head akin to the size of a modern sheep’s, was quadrupedal (meaning it walked on four feet, although it was capable of standing and walking on two feet), and had short forelimbs and long hindlimbs.
Anchisaurus had large, curved claws on its thumbs, which it used to pull leafy branches to its mouth, and to its spoon-shaped, serrated teeth, which were ideal for shearing foliage from trees. These claws were also employed to ward off predators. It’s been suggested that Anchisaurus may have hopped along slowly, much like a kangaroo, while foraging for food. Anchisaurus reared up on its hind legs, as well, to access higher branches, and to protect its neck from Dilophosaurus and Megapnosaurus, the Early Jurassic’s chief meat eaters. Its long, strong tail, used as a counterbalance when the dinosaur ran on its hind legs, could be whipped from side to side to deter predators. Anchisaurus was lightly built and nimble enough to often speedily escape from its enemies.
When Anchisaurus lived in New England, the Atlantic Ocean was just starting to materialize. Massive fern forests thrived in the warm, wet climate. These forests safeguarded Anchisaurus from predators and supplied it with an abundance of food. Plant eating had its advantages. Leaves were easily and widely available. Plants don’t need to be hunted, nor do they try to escape.
But that food had to be digested, and digesting plant matter was a much more challenging process than digesting meat. This is because meat lacks the tough fibers found in plants. Plants consist primarily of cellulosic fiber, which is outrageously hard to break down. Anchisaurus needed to swallow stones, also called gastroliths, to assist in breaking down the food in its stomach, much of which was swallowed whole because the dinosaur lacked the proper teeth for chewing. These stones accumulated in part of the stomach called the gizzard, which ground up the plant material so it could be digested. Herbivorous dinosaurs like Anchisaurus generally needed a large belly for this process. Since the belly was located in front of the pelvis, balancing on two legs became trickier as dinosaurs became larger, and they eventually adopted the quadrupedal position characteristic of the giant sauropods.
Some paleontologists have posed the possibility that Anchisaurus may have eaten meat, since its eyes faced forward like a predator’s, rather than to the sides, like most prey animals. Also, the thumb’s claw was much sharper than needed for a plant eater. However, what is known is that Anchisaurus was descended from meat eaters, and that its carnivorous features may not have yet completely evolved into those of a plant eater.
Although Anchisaurus was small, it was mighty – it was the first dinosaur discovered in America, and the first to pave the way for identification of future dinosaur finds. Even though it lived millions of years ago, it is still teaching us countless valuable lessons today.
