The Brontosaurus skeleton, often called the “thunder lizard,” is a remarkable symbol of prehistoric life. Its immense size and ancient lineage offer tangible connections to a time when colossal creatures roamed the planet. Displayed in museums worldwide, these impressive fossils underscore their role in understanding Earth’s deep history.
The Brontosaurus’s Journey from Obscurity
The scientific journey of the Brontosaurus involves discovery, reclassification, and eventual re-validation. American paleontologist Othniel Charles Marsh first named Brontosaurus excelsus in 1879, based on a partial skeleton found in Wyoming. This discovery occurred during the “Bone Wars,” a period of intense rivalry among paleontologists in the late 19th century. Marsh’s initial specimen was notable for its completeness, though it lacked a skull.
In 1903, paleontologist Elmer Riggs concluded that Brontosaurus excelsus was not distinct enough to be a separate genus. He reclassified it as a species of Apatosaurus, which Marsh had named two years earlier. Due to scientific naming rules, Apatosaurus took precedence, and Brontosaurus became a synonym. For over a century, the scientific community largely adhered to this reclassification, treating Brontosaurus as Apatosaurus excelsus.
This long-standing classification was challenged by a 2015 study from a joint British-Portuguese research team. Their research analyzed numerous anatomical traits across many sauropod specimens. Findings provided evidence that Brontosaurus possessed distinct characteristics, particularly a more slender build and a higher-set neck compared to Apatosaurus, to warrant its re-establishment as a valid genus.
Anatomy of a Colossus
The Brontosaurus was a quadrupedal sauropod dinosaur, characterized by its distinctive skeletal features and immense proportions. Brontosaurus excelsus, the largest species, could reach 21–23 meters (69–75 feet) long and weigh 15-20 metric tons (17-22 short tons), making them among the largest land animals of their time. Their bulky, barrel-shaped bodies were supported by thick, pillar-like legs.
Its exceptionally long neck was composed of robust cervical vertebrae. While historical depictions showed the neck held vertically, current understanding suggests a more horizontal posture for grazing. Its long, whip-like tail likely served multiple functions, including balance and defense.
The skull of the Brontosaurus has a notable history of misidentification in museum mounts. Early reconstructions often mistakenly used a skull from a Camarasaurus due to the absence of a complete Brontosaurus skull. The actual skull is relatively small and delicate, resembling that of an Apatosaurus. Its forelimbs were slightly shorter and stouter than its elongated hindlimbs, supported by a heavily built shoulder girdle and pelvis.
Assembling the Past
Bringing a Brontosaurus skeleton from ancient rock to museum display involves specific paleontological techniques. Fossilization begins when a dinosaur dies and its remains are quickly buried by sediment, such as mud or sand. Over millions of years, minerals from groundwater seep into the bones, replacing organic material and turning them into stone through a process called permineralization. This process creates a heavy, rock-like copy of the original bone.
Once a fossil site is identified, paleontologists excavate the remains using hand tools or pneumatic tools for harder rock. Large or fragile fossils are encased in plaster jackets in the field for transport to a laboratory. In the lab, preparators remove the surrounding rock matrix from the fossil using specialized tools, including air scribes and micro-needles. They also clean, repair, and stabilize the fossilized bones.
Mounting a complete dinosaur skeleton for museum display is a scientific process. Original fossil bones are often too heavy and fragile for direct mounting. Museums frequently use lightweight casts made from fiberglass or other materials. These casts, sometimes combined with original bones, are assembled onto a custom-built steel armature, a metal framework that supports the skeleton in a lifelike pose. This process ensures the preservation of the fossils while allowing the public to visualize these creatures.
Where to Encounter a Brontosaurus Skeleton
Experiencing the scale of a Brontosaurus skeleton firsthand offers a profound connection to Earth’s deep history. While complete original skeletons are exceptionally rare, many natural history museums display impressive casts or composite skeletons. These exhibits provide an accurate representation of the dinosaur’s immense size and form.
The American Museum of Natural History in New York City features a notable sauropod exhibit, including an Apatosaurus mount that was historically referred to as Brontosaurus. This museum was one of the first to display a mounted sauropod skeleton, doing so in 1905.
Another significant location is the Yale Peabody Museum of Natural History in New Haven, Connecticut. This museum houses the holotype specimen of Brontosaurus excelsus, the original fossil discovered by Othniel Charles Marsh. Following the 2015 re-validation, the Yale Peabody Museum was among the first to officially rename its iconic skeleton back to Brontosaurus, emphasizing its historical ties to the dinosaur’s discovery. Visiting these institutions offers a unique opportunity to witness the grandeur of the “thunder lizard” and appreciate the ongoing scientific efforts to understand prehistoric life.