Camarasaurus
More than a quarter of all identifiable sauropod finds from the Morrison Formation belong to a single genus. Its name: Camarasaurus. Few long-necked dinosaurs of the region were found as often in the Late Jurassic. Yet hardly anyone knows this dinosaur. Brontosaurus and Brachiosaurus are much better known. Yet its history hides a wild naming dispute from the early days of paleontology.
At a glance
| feature | Value |
|---|---|
| genus | Camarasaurus |
| species | 3 recognized species: Camarasaurus grandis, C. lentus, C. supremus |
| length | 14.9–20 m, depending on the species |
| Weight | 11.5–30 t, depending on the type |
| Location | USA: Wyoming, Colorado, Utah, New Mexico, Oklahoma; occasionally Montana |
| formation | Morrison Formation |
| age | Upper Jurassic (Kimmeridgian to Tithonian) |
| Nutrition | herbivores |
| Family | Camarasauridae |
Three types, one robust design
Camarasaurus grandis, lentus and supremus shared the same body plan. Four sturdy legs carried the body. The hind legs were stronger than the front legs. The tail stayed short: only about 53 vertebrae (Gilmore 1925). How big did Camarasaurus get? That depended on the species. Camarasaurus supremus had the largest body size: up to 20 meters long. Its weight: up to 30 tons. That is as heavy as five elephants together. Camarasaurus grandis stayed smaller. Only 14.9 meters long, only 11.5 tons.
The forehand was striking. The metacarpal bones formed a narrow tube. This was the case with all large sauropods. A study from 2026 asked: How flexible were the fingers within this tube? The answer: hardly any. The fingers could almost only bend backward. Curling inward was nearly impossible. This very feature protected the closely spaced fingers. They didn't block each other when walking (Senter 2026).
How do you distinguish between the three Camarasaurus species?
At first glance, all three species look similar. A closer look at the spine provides further clues. In Camarasaurus grandis, a vertebral process sits atop a high pedicle. In the other two species, this pedicle is short and solid. The opposite is true at the base of the tail. There, a process widens evenly in Camarasaurus lentus. In the other species, it is more T-shaped, with a narrow center.
Time also separates the three species. Camarasaurus grandis is the oldest species, appearing first in the Morrison Formation. Camarasaurus lentus follows, and Camarasaurus supremus appears last. It is also the largest of the three species. Their locations also differ. Camarasaurus grandis is primarily found in Wyoming, Colorado, and New Mexico. Camarasaurus lentus lived in Wyoming and Utah. Camarasaurus supremus comes from southern Colorado, and likely also Oklahoma.
What teeth did Camarasaurus have?
Camarasaurus fed with spoon-shaped teeth. They were broad and had no serrated edge. The largest crowns were just under 5 centimeters tall, about as long as a matchbox. The wrinkled enamel was striking (Wiersma & Sander 2017).
A very well-preserved skeleton from Wyoming shows how many teeth there were. On each side there were four teeth in the premaxilla, nine in the maxilla and 13 in the lower jaw. The upper teeth curved inward, the lower ones stayed straight. In Giraffatitan, a relative of Brachiosaurus, the teeth were much slimmer by comparison.
The teeth did not last forever. They wore down at the edges. The replacement was already growing underneath. The new tooth dissolved the root of the old one from the inside and pushed it out of the jaw. In this animal the wave of replacement ran from back to front. At the front the teeth were replaced faster, probably because they were under more stress (Wiersma & Sander 2017).
This fits the powerful skull. A computer model shows: Camarasaurus had larger chewing muscles and bit harder than Diplodocus. According to the researchers, this allowed it to eat tougher plants (Button et al. 2014). This is an interpretation from model calculations, not direct proof.
Did Camarasaurus have a beak?
Maybe. The evidence points that way, but proof is missing. In the Wyoming skeleton, the tooth roots stuck out of the jaw by about 2 centimeters on average. In some teeth the root was almost dissolved, and yet they still sat in place. Something had to hold them. On a rock slab at the lower jaw, impressions of soft tissue were preserved that reach to the middle of the tooth crowns. The researchers suspect gums and a horny beak in front of them, which protected the teeth from wear (Wiersma & Sander 2017).
In 2026 a new method was added. A team from Italy and Switzerland examined the openings in the facial skull through which nerves and blood vessels ran to the outside. It compared them with 307 living species. The pattern of Camarasaurus resembles that of birds with a horny beak. The team calls the structure “Odontoscutum”: a horny covering that sits next to complete teeth and protects and supports them. It lay on the side of the premaxilla, maxilla and lower jaw (Gobbo et al. 2026).
Two caveats belong here. The work is a preprint and has not yet been reviewed by other experts. And the sample is small: only three sauropod skulls were included.
From cub to 16-meter giant
Two skeletons from Utah show how small Camarasaurus was as a juvenile. The site: the Carnegie Quarry in Dinosaur National Monument. The smaller animal measured only 5.08 meters. That is barely longer than a large SUV with a trailer. The smaller skeleton is almost complete. Charles Gilmore described it as early as 1925: 82 vertebrae, in a row from the snout to the tip of the tail (Gilmore 1925). The animal lay on its right side, its neck bent upward in an S shape. The second, older animal reached about 8 meters. Even the holotype of Camarasaurus lentus was still small: only 6.11 meters. Adult animals of this species grew up to 16 meters long (Carpenter, Ikejiri & Wilson 2026 – no DOI available).
Was it really a new animal?
In 1918, Earl Douglass discovered the skull of the smaller juvenile. Douglass led the excavation. At first, he thought the find was a Brontosaurus. Shortly afterward, he corrected himself, giving the animal a new name: "Uintasaurus." The reason: its unusually long neck ribs. Douglass considered them unique. Later research revealed otherwise. Long neck ribs are quite normal in Camarasaurus. The supposedly new Uintasaurus was simply a young specimen of Camarasaurus lentus.
One name, eleven fossils, six researchers
Few other species were renamed so frequently in their early days. Edward Drinker Cope described Camarasaurus supremus in 1877, using individual vertebrae from Colorado. That same year, much more happened. Cope and his rival, Othniel Charles Marsh, assigned at least eleven other names. All were supposedly for new giant dinosaurs from the surrounding area, including Atlantosaurus and Apatosaurus. It wasn't until much later that the confusion surrounding the names was resolved. Many of these "new" animals were simply Camarasaurus. Others were Brontosaurus or Apatosaurus under double names.
Camarasaurus or Brachiosaurus – how do you tell them apart?
Both giants lived in the same place around 150 million years ago. Both belong to the Macronaria, a common group of sauropods. The biggest difference lies in their body structure. Brachiosaurus had forelegs longer than its hind legs. This gave it the typical, sloping shoulder. In Camarasaurus, it was the other way around. The hind legs remained longer than the forelegs. The animal therefore stood more horizontally.
A giant as prey
A discovery from 1898 shows that even large Camarasaurus animals were not safe. Deep grooves were found on several tail vertebrae of a large animal. Their pattern matches the teeth of a large carnivore. This is direct evidence of an attack. The find comes from a time when a different theory prevailed. Researchers at the time believed that sauropods, like alligators, lived mostly in water. This theory is now considered disproven.
The northernmost find of the Morrison Formation
In 2017, researchers described a partial skeleton from Montana. The site is located in the Little Snowy Mountains. It is the northernmost known sauropod find in the entire Morrison Formation. An examination of the bone revealed a surprise: despite its small size, the animal was an adult. This shows that size alone does not indicate age in sauropods.Woodruff & Foster 2017).
Macronaria also include Aragosaurus from the Late Jurassic of Spain and Alamosaurus from the Late Cretaceous of the USA.
More information on this topic can be found at urzeittiere.net
Interested in the sauropods of the Morrison Formation? Then the article on [topic missing] is also worth reading. Brachiosaurus. He was the long-legged relative with the distinctive front leg overhang. There is also an article about Brontosaurus. Its naming history is closely linked to that of Camarasaurus. Also Plateosaurus is worth a look. It was an older, smaller relative from the Triassic period. And then there's Cathetosaurus. The find is controversial. Perhaps it's just an old specimen of Camarasaurus grandis.
Image sources:
Size comparison: Gunnar Bivens, CC BY-SA 4.0, via Wikimedia Commons
Skull of Camarasaurus supremus, Royal Tyrrell Museum: Chris Woodrich, CC BY-SA 4.0, via Wikimedia Commons
Bite marks on the shoulder blade of a Camarasaurus supremus. Specimen AMNH FARB 5760 sc-3: Roberto Lei, Emanuel Tschopp, Christophe Hendrickx, Mathew J. Wedel, Mark Norell, David WE Hone, CC BY 4.0, via Wikimedia Commons