Species: Apatosaurus ajax (Ah-pat-oh-sore-us ae-jacks)
What it means: Deceptive lizard
Other Species: Apatosaurus louisae
Where I live: Western U.S.A.- The Morrison Formation
When to find me: The Late Jurassic period, about 152 million years ago.
My favorite food: Plants! I’m an herbivore.
My neighborhood: The Morrison Formation covers a huge expanse of land with a variety of different habitats teaming with life. Most of it was very much like the Serengeti of modern day Africa, only with prairies of drought-tolerant ferns and cycad relatives instead of grass. Dense woodlands of tall conifers like the modern araucaria, ginkgoes, and tree ferns would only lie in places of plentiful water such as the few permanent rivers. Other areas had far more sparse and shrubbier vegetation like the open woodlands of acacia trees in the Serengetti.
Life in this environment would’ve adapted to long months of harsh drought, followed by a few months of monsoon that flooded the rivers. Many of the larger herbivores may have migrated like the herds in Africa do today, while most carnivores stayed behind to feast on the dead and dying, or else become opportunistic hunters of less traditional diets for lean times, such as fish or turtles in the rivers.
A few of my neighbors: First let me share my herbivorous friends…
- Long-necked sauropods like Brachiosaurus, Camarasaurus, Diplodocus, Barosaurus, Suuwassea, Supersaurus, Haplocanthosaurus, and Dystrophaeus.
- Armored dinosaurs like Stegosaurus, Hesperosaurus, Mymoorapelta, and Gargoyleosaurus.
- Two-legged ornithopods like Dryosaurus, Camptosaurus, and Nanosaurus
The predators in the neighborhood include dinosaurs like Allosaurus, Torvosaurus, Ceratosaurus, Saurophaganax, Marshosaurus, Stokesosaurus, Ornitholestes, Coelurus, Tanycolagreus, Elaphrosaurus, and Koparion.
Plus there are all the tiny critters on the ground I try not to step on…countless lizards, crocodile relatives on land and water, mammals, frogs, turtles, fish. Some of the pterosaurs flying in the sky help me with any bugs that might try to bite me.
- Apatosaurus gets its name from the greek apate/apatelos (deception/deceptive) + sauros (lizard). The paleontologist Othniel Charles Marsh named it for the chevrons, which are long, thin bones on the underside of the tail. He thought they looked more like the chevron bones of mosasaurs (a large, marine reptile) than other dinosaurs.
- The type species is named after Ajax, a hero in Greek mythology. But the few fossil specimens of this species are incomplete, and the holotype (fossil specimen that determines which fossils are Apatosaurus) is a juvenile. The second and far more well known species is Louisae, named after Louise Carnegie. Her husband, Andrew Carnegie, helped fund much of the field research to find more complete dinosaur skeletons in the American West and founded the Carnegie Museum. Of the two valid species, A. lousiae is the most well studied because its fossils are much more numerous and complete, including a few skulls.
- Othniel Charles Marsh named Brontosaurus when there were still few fossils known for Apatosaurus. Like many new species named at the time, it appeared very different from what he had, and so was given a new genus name. Years later, more fossils like those of “Brontosaurus” were discovered, but it looked like the only differences from Apatosaurus had to do with age. Since the Apatosaurus holotype was only a juvenile, it was determined that there were not enough differences to make Brontosaurus a separate genus from Apatosaurus. Elmer Riggs published the paper in 1903, which stated that Brontosaurus was not a valid genus.
- In April 1905, the “mounting of the largest skeleton, the Amphibious Dinosaur Brontosaurus,” was finished at the American Museum of Natural History. It was the most complete sauropod ever discovered, only missing the head, feet, and parts of the tail.
- Dinosaur enthusiasts (including myself) were forever correcting the masses, and saying “It’s Apatosaurus, not Brontosaurus!” Until at last Brontosaurus got its awesome name back and was reestablished as its own genus in 2015.
- The first, and nearly complete, fossils of Apatosaurus loiusae were described and named in 1916. A head was found nearby, but it was so small and delicate compared to the rest of the skeleton that the few who thought it was the correct one where considered crazy by the scientific community. The skeleton was mounted at the Carnegie Museum, headless.
- The Carnegie Apatosaurus was finally given a head in 1934, but the head was a cast of a Camarasaurus skull. Camarasaurus was a smaller sauropod than Apatosaurus, but the head is larger, stronger, and more boxy in shape, a head that looked suitable for the huge and robust Apatosaurus. The mounted skeleton had the wrong head until 1979, when sauropod expert J.S. McIntosh and Carnegie Museum Paleontologist David Berman determined that the delicate skull first found near the original fossils was most likely the head after all.
Fossil Finds: Many individuals, especially of A. louisae. Most fossils are fragmentary, especially adult specimens, but a few are almost complete. Combined with tracks and other trace fossils, we have great knowledge about Apatosaurus.
Mathew, W. D. (1905) “The Mounted Skeleton of Brontosaurus.” The American Museum Journal. https://archive.org/stream/p2naturalhistory05ameruoft#page/n5/mode/2up
Foster, John. Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press, 2007
Parson’s, Keith M. “The Wrong-Headed Dinosaur.” Internet Archive Wayback Machine, https://web.archive.org/web/20100414165426/http://www.carnegiemuseums.org/cmag/bk_issue/1997/novdec/feat5.htm
“Apatosaurus.” Wikipedia, https://en.wikipedia.org/wiki/Apatosaurus