Brontosaurus

The Brontosaurus belongs to the genus Brontosaurus. The Brontosaurus was one of the largest herbivorous species in the sauropod dinosaurs family, that was lived during the Late Jurassic and Early Cretaceous epochs. The Late Jurassic and Early Cretaceous epochs were about 163.5 million to 100.5 million years ago. In 1874, the Brontosaurus dinosaur’s first fossil elements were discovered from western North America. Later, in 1879, the American paleontologist Othniel Charles Marsh described the Brontosaurus fossil elements.

In 1903, scientists discovered that fossil elements belonged to the genus Brontosaurus, in Greek Brontosaurus means ‘thunder lizard’. In earlier days the Brontosaurus has belonged to the genus Apatosaurus.  Even though the classification of Brontosaurus was changed, the public still embraced the dinosaur as Brontosaurus, because of the widespread motion pictures and televisions with the presence of Brontosaurus reconstructions in museums throughout North America and Europe during the 20th century. In 2015, the genus Brontosaurus was reinstated after a morphological study of the family. Because the genera belonged exposed the physical differences between Brontosaurus and Apatosaurus, which were enough to separate them into two genera. The genus Brontosaurus is consists of only one species i.e,  B. excelsus.

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Controversy in Taxonomic Classification 

The Brontosaurus is completely excavated from the world, but their headless, skeleton from rocks helped to the age of Brontosaurus species using carbon dating. The American Journal of science described that they were from the Jurassic Period at Como Bluff Quarry 10, Wyoming. Later, Brontosaurus became one of the iconic sauropods within scientific circles. In 1883, the Marsh created a poster-sized paper for reconstructing the specimen.  During that phase, the  Brontosaurus had gained fame, which has been the most complete sauropod fossil ever discovered, further, the illustrations of the dinosaur also appeared in newspapers and other periodicals during the late 19th century brought peoples to know about Brontosaurus. The Museum was planned to construct to protect Brontosaurus reconstructions in their institutions. In 1905, the first museum to protect the dinosaur reconstruction of a sauropod dinosaur was developed in New York City and are named the American Museum of Natural History.

In 1903, the controversy arose between scientists about the reevaluation of genus Apatosaurus and genus Brontosaurus specimens by American paleontologist Elmer Riggs. Later, he concluded that Marsh’s Apatosaurus specimen was a younger version of the same type of sauropod represented in the  Brontosaurus specimen and that the two genera should be combined into one genus. The genera Apatosaurus was first described in 1877, which was just two years before describing Brontosaurus. According to the taxonomic naming rules, both genera are under the classification of dinosaurs. Later, the species Brontosaurus excelsus was changed to Apatosaurus excelsus was joined with Apatosaurus ajax, which was already kept under the genus Apatosaurus. 

Again confusion arose for Marsh about the association of Apatosaurus and Brontosaurus with a sauropod later identified as Camarasaurus to identity the accurate reconstruction and measurement. Because the Brontosaurus skeleton was not found with their skull. So, their reconstructions of that animal skeletons are purely theoretical skull-based and partly on that of Camarasaurus. That error was highlighted from the perceptions of paleontologists, museum curators, and the public for decades.  Till 1978, scientists were not found that the Brontosaurus genus was once kept under the Apatosaurus. Because the head of both the genus resembled the sauropod Diplodocus. 

In 1978, the accurate measurements were taken by the scientists with their maximum head-to-tail length for Apatosaurus, which was recorded and estimated at about 21 to 22.8 meters. And the weight of Apotosaurs was about 41.3 tonnes. According to the study of Swiss paleontologist Emanuel Tschopp and their colleagues, the average size of Brontosaurus weigh was about 30.5 tonnes and the head to tail length of Brontosaurus was about 27.4 meters. So, according to a recent study, the average weight of Apatosaurus was heavier than the average weight of Brontosaurus. 

Even though the changes in the genus name occurred many years ago, the Museums were slow to adopt the change in classification, and many specimens are still labelled as Brontosaurus till the 1980s. So, the appeal of pairing the moniker Brontosaurus with the sauropod form did not fade easily. In order to overcome the slow acceptance of the change in genus name, Riggs decided to publish his conclusions in the little-known journal Geological Series, which created an issue among the Field Columbian Museum in Chicago. Later, AMNH paleontologists Henry Fairfield Osborn and William Diller Matthew disagreed with Riggs’s conclusion and continued to refer to the dinosaur as Brontosaurus in the museum’s collections and named as Brontosaurus in all other publications.

Similarities Between Apatosaurus and Brontosaurus

Both the Brontosaurus and Apatosaurus species show many similarities in anatomy and habit. Like Brontosaurus,  Apatosaurus was also quadrupedal, which means they were possessing four stout legs, as well as a long neck, which was balanced by a long tail. The Brontosaurus was a herbivorous animal, which preferred to lived on land. The long neck of Brontosaurus species may be evolved to reach marshy vegetation, which was a distance away, or to reach leaves taller trees for their feed. Brontosaurus may also consume stones, which help them to grind up and digest unchewed plant matter when the stoned reached the stomach. While measuring the first museum specimens of Brontosaurus, their head to tail length was about 20.3 meters and their initial weight was measured about  28.1 and 34.5 tonnes.

Characteristics of Brontosaurus 

Physical Appearance of Brontosaurus 

The brontosaurus dinosaur has an elaborated body. In greek the brontosaurus means thunder lizard, which had a long-necked, quadrupedal animal with a long, whip-like tail, and their forelimbs were slightly shorter than that of hind limbs. The Brontosaurus excelsus is the largest species and their average weight was about 15ft and the total length from head to tail of Brontosaurus was measured about 22 meters. 

Still, the skull of Brontosaurus was not found, but according to the study, scientists found that the skull structure of Brontosaurus is closely related to Apatosaurus. Like other sauropods, the Brontosaurus dinosaurs also had the vertebrae of the neck, which were deeply bifurcated; and that were carried paired spines and resulted in the wide and deep neck. 

The spine and neck of Brontosaurus dinosaurs consist of 15 cervicals, ten dorsals, five sacral, and about 82 caudals. The number of caudal vertebrae also varies, even within a species. The cervical vertebrae of Brontosaurus dinosaurs are heavier than other diplodocids but they are not stout as in the specimens of matured Apatosaurus. The dorsal ribs of these animals are not fused or tightly attached to their vertebrae, because they were loosely articulated. The Brontosaurus in the Cretaceous epochs period had ten dorsal ribs on either side of their body. They have a large neck, which was filled with an extensive system of weight-saving air sacs. 

Both  Brontosaurus and Apatosaurus are closely related to each other as they both had tall spines on their vertebrae, which were made up of more than half the height of the individual bones. The shape of the tail was unusual for diplodocids and they are comparatively slender, due to their vertebral spines rapidly decreasing in height and are from their hips. Usually, the  Brontosaurus spp have long ribs, which compared to the other diplodocids, which were given unusual deep chests. Like other diplodocids, the last portion of the tail of Brontosaurus possessed a whip-like structure.

The limb bones of Brontosaurus are very robust. The arm bones of the brontosaurus dinosaur are also stout and show the humerus resembles the Camarasaurus. The physical characteristics of the brontosaurus excelsus are also nearly identical to Apatosaurus ajax. 

In 1936, Charles Gilmore noted that the previous reconstructions erroneously proposed the radius and ulna could cross, when the life of them would have remained parallel. The brontosaurus dinosaurs had a large claw on each of their forelimbs, and the first three toes possessed claws on each foot. 

In 1936, scientists said that no sauropod species had more than one hand claw preserved. But now this one claw is accepted as the maximum number throughout the entire group. Usually, the single front claw of the brontosaurus was slightly curved and squarely shortened on the front end. The hip bones of these animals were robust ilia and the fused pubes and ischia. The tibia and fibula bones in the lower leg brontosaurus were different from the slender bones of Diplodocus but they remain nearly indistinguishable from the  Camarasaurus. The fibula, the outer and usually smaller of the two bones between the knee and the ankle, were longer than the tibia, although they are more than slender.

Posture and Locomotion of Brontosaurus 

According to the research, the sauropods like Brontosaurus had a massive structure. So they preferred to live in the dry land. And theoretically, they must have lived partly submerged in water, possibly in swamps. But the recent findings do not support for partly submerged in water, they must be complete terrestrial animals.

Like Diplodocids, the  Brontosaurus also often portrayed their necks to help high up in the air, which allows them to browse on tall trees to obtain their feed. Some studies suggested and believed that the necks of diplodocids are less flexible, but other studies found that all tetrapods appear to hold their necks at the maximum possible vertical extension when they are in a normal, alert posture. While arguing about the same would show the truth about sauropods barring any unknown, it may be their unique characteristics that set the soft tissue anatomy of their necks apart from other animals. 

Brontosaurus also had their trackways like other sauropods, the average range of brontosaurus, which was lived in the cretaceous epochs period was about 20 to 40kms per day. According to their physical characteristics, they must have the potential to run at a speed of about 20 to 30km/h. These species must be slow locomotive species while comparing to other sauropods. Because they had minimal muscling or recoil after strides. 

The single claw present on the forelimb of sauropods had proposed various uses. They may be helpful for defence, but the shape and size of a single claw make them this unlikely. Other predictions about claw were it may be for feeding, but most probably the claw was for grasping objects like tree trunks when they were rearing.

Physiology

In 1991, the scientist James Spotila et al proposed that Brontosaurus and other sauropods have a large body size and they were unable to maintain high metabolic rates so they would not release enough heat from their body. However, the temperature in the Jurassic was 3 degrees Celsius, which helped them to sustain. He also suggested that the animals must have a reptilian respiratory system. Later, Wedel found that an avian system must be allowed them to dump more heat. Also, some scientists study argued that the heart of Brontosaurus should have trouble sustaining sufficient blood pressure to oxygenate the brain.