The Super Lizard: One of the Longest Animals to Walk the Earth

In the pantheon of giant dinosaurs, few names convey their subject’s essence as directly as Supersaurus. This was, quite simply, a super lizard—a sauropod of staggering proportions that ranks among the longest animals ever to have walked the Earth. Stretching over 33 meters (108 feet) from the tip of its tiny head to the end of its whip-like tail, Supersaurus was a living bridge between two horizons, a creature so vast that its heart had to pump blood several stories upward to reach its brain. Discovered in the legendary dinosaur graveyards of western Colorado, Supersaurus has helped reshape our understanding of just how large terrestrial animals can become—and how the physics of biology can be pushed to its absolute limits.

Discovery and Naming

The Dry Mesa Quarry

Supersaurus was discovered in 1972 by James A. Jensen, a self-taught paleontologist and fossil preparator at Brigham Young University (BYU). Jensen was working at the Dry Mesa Dinosaur Quarry, a rich fossil site in the Morrison Formation near Delta, Colorado. The Morrison Formation—a vast expanse of Late Jurassic sedimentary rocks spanning much of the western United States—is the single most important source of Jurassic dinosaur fossils in the world, having yielded iconic species including Allosaurus, Stegosaurus, Diplodocus, Apatosaurus, and Brachiosaurus.

At Dry Mesa, Jensen uncovered a series of enormous bones that dwarfed even the large sauropods already known from the Morrison Formation. The most spectacular find was a single scapulocoracoid (shoulder blade and associated bone) measuring approximately 2.4 meters (8 feet) in length—the largest single bone from any dinosaur known at that time. Additional vertebrae and limb elements confirmed that these bones belonged to an animal of exceptional size.

A Name That Says It All

Jensen formally described the animal in 1985, naming it Supersaurus vivianae. The genus name Supersaurus is refreshingly straightforward—Latin/Greek for “super lizard”—reflecting the animal’s extraordinary size. The species name vivianae honored Vivian Jones, a friend and supporter of Jensen’s paleontological work.

The naming and classification of Supersaurus was complicated by the chaotic conditions at the Dry Mesa quarry, where bones from multiple enormous sauropods were jumbled together. Jensen initially believed he had found three different giant sauropods, which he named Supersaurus, Ultrasauros (later corrected to Ultrasaurus), and Dystylosaurus. Decades of subsequent research revealed that some of these names were based on mixed material—bones from different individuals and even different species that had been mistakenly combined. Eventually, detailed anatomical studies established that Supersaurus was a valid genus, while Ultrasauros was based on a chimera of Supersaurus and Brachiosaurus bones and was therefore invalid.

The Jimbo Specimen

The understanding of Supersaurus was dramatically improved by the discovery of a much more complete specimen in 1996, informally known as “Jimbo.” Found in the Morrison Formation of Converse County, Wyoming, Jimbo preserved approximately 30% of the skeleton—a remarkable level of completeness for a giant sauropod. This specimen confirmed that Supersaurus was a diplodocid, closely related to Diplodocus and Apatosaurus, and provided the data needed to generate reliable size estimates and understand the animal’s proportions.

Physical Characteristics

Staggering Dimensions

Supersaurus was one of the longest dinosaurs for which we have good fossil evidence. Total length estimates based on the Jimbo specimen and the original Dry Mesa material range from 33 to 35 meters (108 to 115 feet), with some researchers suggesting even greater lengths may have been possible. For perspective, this is longer than a blue whale—the largest animal alive today—and roughly the length of three standard school buses parked end to end.

Despite this extraordinary length, Supersaurus was not the heaviest sauropod. Its diplodocid body plan was relatively slender compared to the more massive titanosaurs, and estimated body weight ranged from 35,000 to 40,000 kilograms (35 to 40 metric tons)—enormous by any standard, but considerably lighter than contemporaries like Brachiosaurus (50-60 tons) and later giants like Argentinosaurus (70-100 tons). Supersaurus achieved its record-breaking length through elongation rather than bulk, with an extraordinarily long neck and tail accounting for the majority of its total length.

The Neck

The neck of Supersaurus was one of its most remarkable features, estimated at approximately 13 to 15 meters (43 to 49 feet) in length—long enough to span the width of a tennis court. This neck was composed of 15 cervical vertebrae, each of which was a marvel of biological engineering. The individual vertebrae were massive yet lightweight, riddled with air sacs (pneumatic chambers) that reduced their weight by up to 60% compared to solid bone. Complex laminae (thin sheets of bone) and struts within the vertebrae provided structural support while minimizing mass—a design principle remarkably similar to the I-beams used in modern architecture and engineering.

The neck was held in a roughly horizontal or gently upward-sloping posture, allowing Supersaurus to sweep its head across a vast arc of vegetation without moving its enormous body. This “feeding envelope” strategy—maximizing the area of vegetation accessible from a single standing position—was energetically efficient and may have been a key adaptation that allowed sauropods to sustain their enormous bodies.

The Tail

The tail of Supersaurus was equally impressive, probably containing 80 or more caudal vertebrae and tapering to a slender, whip-like tip. Computer simulations of diplodocid tails have shown that these structures could be cracked like a bullwhip, generating sonic booms that would have exceeded 200 decibels at the tip. Whether Supersaurus actually used its tail in this manner is debated, but possible functions for a whip-cracking tail include:

• Defense against predators: A supersonic tail crack would have been a devastating weapon against theropods
• Communication: The loud crack could have served as a long-distance signal to other sauropods
• Intraspecific competition: Males may have used tail-cracking in dominance displays or direct combat

Cardiovascular Engineering

One of the most fascinating aspects of Supersaurus biology is the cardiovascular challenge posed by its extreme dimensions. With a head potentially elevated 8 to 10 meters (26 to 33 feet) above the heart (depending on neck posture), the circulatory system faced the enormous task of pumping blood uphill against gravity to the brain. Maintaining adequate blood pressure at the brain while avoiding dangerously high pressure at the feet required remarkable physiological adaptations.

Estimates suggest that Supersaurus may have had:

• A heart weighing 300 to 500 kilograms with extremely thick muscular walls
• Blood pressure two to three times higher than that of modern mammals
• Specialized valves in the neck arteries to prevent backflow
• Thick-walled blood vessels in the lower extremities to withstand high hydrostatic pressure
• Possibly a system of arterial sphincters to regulate blood flow during changes in head position

Habitat and Environment

The Morrison Formation World

During the Late Jurassic, approximately 153 to 145 million years ago, western North America was a broad, semi-arid floodplain dotted with rivers, lakes, and seasonal wetlands. The climate was warm and seasonal, with distinct wet and dry periods that influenced the distribution of water and vegetation. Open forests of conifers, ferns, cycads, and ginkgoes provided food for the enormous sauropod populations, while denser woodland bordered river channels and permanent water sources.

The Morrison Formation preserves one of the most diverse and well-studied dinosaur ecosystems in the world. Supersaurus shared this landscape with an extraordinary cast of characters:

Herbivores:

• Diplodocus, Apatosaurus, and Barosaurus: Fellow diplodocids of varying sizes
• Brachiosaurus and Camarasaurus: High-browsing sauropods that fed at different levels
• Stegosaurus: The famous plated dinosaur with its thagomizer tail weapon

Predators:

• Allosaurus: The dominant large predator, up to 10-12 meters long
• Ceratosaurus: A smaller theropod with a distinctive nasal horn
• Torvosaurus: A massive megalosaurid rivaling Allosaurus in size

Niche Partitioning Among Giants

One of the most remarkable features of the Morrison ecosystem was the coexistence of multiple giant sauropod species. At some localities, five or more sauropod species have been found in the same rock layers, raising the question of how so many enormous herbivores could share the same habitat without depleting their food sources.

The answer lies in niche partitioning—the ecological separation of feeding strategies:

• Brachiosaurus: A high browser that used its giraffe-like proportions to feed on treetop vegetation
• Camarasaurus: A mid-level browser with robust jaws for processing tougher plant material
• Diplodocus and Supersaurus: Low to mid-level browsers that swept their long necks horizontally to cover vast areas of ground-level and mid-canopy vegetation
• Apatosaurus: A more robust, ground-level feeder with a deeper skull than Diplodocus

By feeding at different heights, on different vegetation types, and possibly in different microhabitats, these sauropods could coexist in the same ecosystem—much as modern African savanna herbivores (elephants, giraffes, zebras, wildebeest) partition their shared habitat.

Growth and Metabolism

How to Build a Giant

Growing to 33+ meters in length required an extraordinary growth rate. Bone histology studies of diplodocid sauropods reveal rapid, sustained growth during the first two decades of life, with annual growth rates comparable to modern whales and elephants. A young Supersaurus may have gained several hundred kilograms per year during its peak growth period, fueled by near-constant feeding.

Sauropods are believed to have been endothermic or at least mesothermic (having metabolic rates intermediate between modern cold-blooded reptiles and warm-blooded mammals). This elevated metabolism was necessary to sustain their rapid growth rates and active lifestyles, but it also meant they needed to consume enormous quantities of food—estimated at 200 to 500 kilograms of vegetation per day for a large adult.

The bird-like respiratory system of sauropods, with its extensive air sacs extending into the vertebrae and other bones, provided the efficient gas exchange needed to sustain this metabolic demand. This pneumatic system also reduced skeletal weight, making the enormous body more manageable.

Interesting Facts

• At 33-35 meters long, Supersaurus was longer than a blue whale and roughly the length of three school buses lined up end to end
• A single shoulder blade of Supersaurus measured 2.4 meters (8 feet)—taller than most adult humans
• The Dry Mesa Quarry where Supersaurus was first found also yielded bones of the giant theropod Torvosaurus and the sauropod Brachiosaurus
• The diplodocid tail may have been capable of breaking the sound barrier, producing a supersonic crack louder than a gunshot
• Supersaurus needed a heart the size of a small car to pump blood to its elevated brain
• Despite being one of the longest dinosaurs, Supersaurus was not the heaviest—later titanosaurs from South America were shorter but much more massive

Frequently Asked Questions

Q: Was Supersaurus the longest dinosaur? A: It was among the longest for which we have reliable fossil evidence. Some other sauropods—such as Seismosaurus (now considered a species of Diplodocus), Amphicoelias, and Maraapunisaurus—may have been longer, but these are known from very fragmentary material and their sizes are uncertain.

Q: How did Supersaurus eat enough food to survive? A: Sauropods like Supersaurus did not chew their food—they simply cropped vegetation and swallowed it whole, relying on their enormous digestive systems to break it down through fermentation. This allowed them to process food much more quickly than if they had to chew each mouthful, enabling the high intake rates necessary to sustain their massive bodies.

Q: Could anything hunt an adult Supersaurus? A: A healthy adult Supersaurus was probably largely immune to predation due to its sheer size. However, juveniles, sick, and elderly individuals were vulnerable to large predators like Allosaurus and Torvosaurus. There is also evidence that Allosaurus may have engaged in pack or mob hunting, which could have posed a threat even to large adults.

Q: How did Supersaurus support its own weight? A: Sauropod skeletons incorporated numerous weight-saving features, including pneumatic (air-filled) vertebrae, columnar limbs that supported weight directly through the bone rather than through muscle tension, and a body plan that distributed mass efficiently. Despite their size, sauropods were remarkably well-engineered for supporting and moving their enormous bulk.

Q: Is Supersaurus the same as Ultrasaurus? A: No. Ultrasauros (often misspelled as Ultrasaurus) was a name given by Jim Jensen to what he believed was a separate giant sauropod from the same Dry Mesa quarry. Later research showed that “Ultrasauros” was based on a mixture of Supersaurus and Brachiosaurus bones and is therefore an invalid name.

Supersaurus vivianae embodies the ultimate expression of the sauropod body plan—an animal stretched to dimensions that seem to defy the limits of terrestrial biology. In its 33-meter frame, we see not just an impressive statistic, but a profound biological achievement: the product of over 100 million years of evolutionary refinement in body size, respiratory efficiency, cardiovascular engineering, and skeletal design. Supersaurus reminds us that the history of life on Earth has repeatedly produced results that exceed what we might consider possible—and that the age of dinosaurs, more than any other era, was a time when those limits were tested as never before.