About Camarasaurus
| Scientific Name (Genus) | Camarasaurus |
| Meaning of Name |
Chambered lizard
kamara(chamber/hollow)[Greek] - saurus(lizard)[Greek] |
| Classification | Saurischia, Sauropodomorpha (Sauropoda, Macronaria) |
| Total Length | Approx. 15-23m |
| Diet | Herbivorous |
| Period | Late Jurassic (Approx. 155 - 145 million years ago) |
| Sub-classification / Species Name |
Camarasaurus supremus
Camarasaurus grandis Camarasaurus lentus * Camarasaurus lewisi (Recently separated into the genus Cathetosaurus) |
| Year of Paper Publication | 1877 |
| Genus Name Publication |
On a gigantic saurian from the Dakota eopoc of Colorado.
Palaeontological Bulletin (25). by E. D. Cope. 1877. |
Features and taxonomic history of Camarasaurus
Camarasaurus is a type of sauropod (macronarian) that thrived most in the Late Jurassic North American continent (present-day Morrison Formation), with over 530 specimens excavated to date.
It reached an estimated weight of 42 tons in the largest species, Camarasaurus supremus, with a total length of 15-23m. Compared to diplodocid dinosaurs, its neck and tail were relatively short, and its height was slightly higher at the hips (pelvis), or the line of its back was kept almost horizontal. Like modern elephants, it had thick columnar limbs structured to efficiently support its massive body with the skeleton itself.
The most prominent feature of Camarasaurus is its robust, "box-shaped" skull and the large, sturdy "spoon-shaped" teeth lined up in its jaws. This powerful head structure indicates that it had a distinctly different diet from other sauropods in the ecosystem of the time.
A dinosaur that had long been considered a species of Camarasaurus (Camarasaurus lewisi) has recently been recognized again as an independent genus called "Cathetosaurus" through detailed phylogenetic analysis. Cathetosaurus has been found to have a peculiar structure with a significantly forward-rotated pelvis and a rib cage hanging lower than its knees, indicating a huge intestine. This has revealed that the diversity of sauropods at the time was much higher than previously thought.
Powerful jaws and the secret of "food partitioning" (diet)
They have a shape called spoon-like. It was a thick and sturdy structure compared to Diplodocus.
The teeth of Camarasaurus were replaced with new ones approximately every 62 days on average. It has also been pointed out that the jaws may have had highly vascularized strong connective tissues (gums or lips), or a keratinized beak. Furthermore, a biomechanical simulation using Finite Element Analysis (FEA) proved that Camarasaurus could generate an extremely powerful bite force compared to Diplodocus and others.
The latest "calcium isotope analysis" by a research team from the University of Texas and others published between 2025 and 2026 revealed how these powerful jaws were used. As a result of analyzing the chemical signals left in the tooth enamel, it was scientifically proven that Camarasaurus actively selected and crushed "hard woody tissues" such as hard branches, twigs, and bark of conifers.
Previously, it was thought that they divided the height of the plants they ate solely by the length of their necks, but in reality, it was found that they cleverly "partitioned food" based on the "parts" and "hardness" of the plants. In addition, gastroliths (stomach stones) found in juvenile fossils are thought to be for mineral supplementation or accidental ingestion during feeding, rather than for aiding digestion like in birds. This confirms that their powerful jaws and teeth could sufficiently crush plants within their mouths alone.
A mechanism by which different species divide their diet, activity times, or habitats to avoid direct competition in a limited environment and survive together (coexist). Camarasaurus was able to prosper in the same land by eating hard woody tissues, while Diplodocus ate soft plants.
A 300km long-distance migration told by teeth
The Late Jurassic North American "Morrison Formation" where Camarasaurus lived was a vast floodplain with a semi-arid climate with distinct dry and rainy seasons. How these giants survived severe food and water shortages during the dry season had been a long-standing mystery.
In 2011, a US research team analyzed the "oxygen isotope ratios" contained in the fossil teeth of Camarasaurus. Oxygen isotopes in the water animals drink have the characteristic that the proportion of heavy isotopes decreases as the altitude increases, and this is recorded in the tooth enamel growing at the time.
As a result of the analysis, signals from periods of drinking water from "high-altitude areas" were periodically found in the teeth of Camarasaurus excavated from lowland strata. From the geographical conditions of the time, the water source is estimated to have been a highland about 300 kilometers away from the fossil discovery site.
In other words, when lowland plant resources were depleted during the dry season, Camarasaurus undertook "seasonal long-distance migrations" to highlands hundreds of kilometers away in search of abundant food and water. This outstanding migration ability is thought to be a major factor in how they achieved gigantism and prospered for a long time.
Growth process and the truth about its posture
From research in "bone histology," which involves observing thin sections of fossilized bone under a microscope, surprising facts about the growth process of Camarasaurus have been discovered. From the cross-section of a small Camarasaurus bone found in Montana, a structure called the "External Fundamental System (EFS)" was discovered, which indicates that growth had completely stopped like the tree rings of a tree.
Calculating the age backward, this individual was estimated to be around 30 years old. This proved that even though its body was small, it was already a "fully grown adult" that had reached its growth limit. This shows that the body size of a sauropod does not necessarily indicate its age or maturity, and that there were major differences in growth depending on the environment and individual differences.
Furthermore, views on the walking posture of Camarasaurus have also changed. In the past, because a famous juvenile fossil (CM 11338) was preserved with its neck bent back extremely towards its spine, it was imagined that it "walked with its neck held vertically high like a swan or a giraffe." However, biomechanical models have now concluded that this posture was physically impossible when alive, and that basically, it had a nearly horizontal posture from its back to its neck.
This is the cause of the misunderstanding that Camarasaurus once had a vertical neck. It refers to the phenomenon where, as the body dries out after death, muscles and ligaments strongly contract, causing the neck and tail to curve back extremely toward the spine.
Life in herds and severe "diseases" left in fossils
Fossils of multiple adults and juveniles caught in mudflows together have been found at excavation sites, revealing that Camarasaurus formed "family groups" or "herds" to some extent. Considering the long seasonal migrations, herd behavior was probably essential for survival. On the other hand, since egg fossils are found in straight lines as if dropped while walking, it is thought that parents did not directly care for their young.
Maintaining a massive body and traveling long distances was a very harsh life. Reports from the field studying pathological lesions left on old bones have found abnormal bone growth in the toe claws of very old Camarasaurus. This is considered evidence that they routinely overused their claws like tools (scratching the ground) to dig up plant roots or dig holes for laying eggs.
Furthermore, the fingers and toes showed signs of severe osteoarthritis and healed fractures sustained during life. From the skull and cervical vertebrae specimens housed at the Gunma Museum of Natural History, traces of "spina bifida" (congenital underdevelopment) – a first among all dinosaurs – and symptoms of multiple vertebrae pathologically fused together have also been found. These fossils depict them living while battling chronic pain and physical stress.
A field that studies pathological lesions, injuries, and fracture marks left on old bones such as fossils to understand what kind of diseases the extinct animals suffered from and what kind of physical stress they experienced in their daily lives.
Cope and Marsh's fossil hunting rivalry
In the spring of 1877, Oramel W. Lucas, a local school teacher in Colorado, USA, discovered fragmentary fossilized giant vertebrae.
Source: On the Vertebrata of the Dakota Epoch of Colorado. the American Philosophical Society, Vol. 17, No. 100. by E. D. Cope. 1877.
Paleontologist Edward Drinker Cope bought these fossils and hastily described (named) Camarasaurus within 1877 to preempt his rivals.
The scientific name Camarasaurus combines the Greek words "kamara" (chamber) and "sauros" (lizard), meaning "chambered lizard." This derives from the characteristic hollows called "pleurocoels" found in the neck and back bones.
These hollows, like those in birds, housed "air sacs" inside, playing a role in significantly reducing the weight of the massive skeleton, which reached up to 20 tons or more.
In late 1877, under Cope's guidance, illustrator John A. Ryder drew a life-size lateral skeletal restoration of Camarasaurus supremus. This holds historical value as the first "sauropod full-skeleton restoration drawing" ever created in the history of paleontology.
His rival, Othniel Charles Marsh, also described a new genus and species of sauropod, Morosaurus grandis, from his own excavations that same year, but it is now considered a synonym for a species of Camarasaurus.
This fierce "Bone Wars" between the two men caused great confusion in classification as new names were given to even slight individual differences, but detailed re-evaluations were conducted into the 20th century, building the foundation of the classification that exists today.
The genus Camarasaurus was named by Edward Cope, but at the lower classification level of species, Edward Cope and Charles Marsh are mixed as namers (describers).
| Year of Description | Describer | Species Name |
|---|---|---|
| 1877 | Edward Cope | Camarasaurus supremus |
| 1877 | Charles Marsh | Camarasaurus grandis |
| 1889 | Charles Marsh | Camarasaurus lentus |
Topics
A real skeleton of Camarasaurus is permanently exhibited at the Gunma Museum of Natural History, and a skull fossil is exhibited at the National Museum of Nature and Science in Ueno, Tokyo.
The full skeleton of Camarasaurus exhibited at the Fukui Prefectural Dinosaur Museum was discovered in Wyoming, USA, in 2007 and purchased by the museum in 2009. Over 90% of the entire body is assembled with real fossils, not replicas, and its impact and reality are unparalleled. The massive skeleton, reaching 15 meters in length, is the culmination of "Project Camarasaurus," in which the museum consistently performed everything from fossil cleaning and research to assembly on its own. It is a symbolic specimen that shows the high level of dinosaur research in Japan domestically and internationally, and its presence impresses visitors.
In 2008, an interactive (pet) robot named "pleo" was released by UGOBE in the US and became popular.
The model for the 30cm long, 1.5kg robot was reportedly a one-week-old infant Camarasaurus.
Camarasaurus Stamp and Fossil Gallery
