Brontosaurus

. The head is based on material now assigned to Brachiosaurus sp. The discovery of a large and fairly complete sauropod skeleton was announced in 1879 by Othniel Charles Marsh, a professor of paleontology at Yale University. The specimen was collected from Morrison Formation rocks at Como Bluff, Wyoming by William Harlow Reed. He identified it as belonging to an entirely new genus and species, which he named Brontosaurus excelsus, meaning "thunder lizard", from the Greek / meaning "thunder" and / meaning "lizard", and from the Latin excelsus, "noble" or "high". By this time, the Morrison Formation had become the center of the Bone Wars, a fossil-collecting rivalry between Marsh and another early paleontologist, Edward Drinker Cope. Because of this, the publications and descriptions of taxa by Marsh and Cope were rushed at the time. Brontosaurus excelsus type specimen (YPM 1980) was one of the most complete sauropod skeletons known at the time, preserving many of the characteristic but fragile cervical vertebrae. Marsh believed that Brontosaurus was a member of the Atlantosauridae, a clade of sauropod dinosaurs he named in 1877 that also included Atlantosaurus and Apatosaurus. including well-preserved limb elements. Marsh referred the skull to B. excelsus, later featuring it in a skeletal reconstruction of the B. excelsus type specimen in 1891 The adult skeleton specifically was very well-preserved, bearing many cervical (neck) and caudal (tail) vertebrae, and is the most complete definite specimen of the species. In 1905, the American Museum of Natural History (AMNH) unveiled the first-ever mounted skeleton of a sauropod, a composite specimen (mainly made of bones from AMNH 460) that they referred to as Brontosaurus excelsus. The AMNH specimen was very complete, only missing the feet, from the specimen AMNH 592 were added to the mount, lower leg and shoulder bones, added from AMNH 222, and tail bones, added from AMNH 339. To finish the mount, the rest of the tail was fashioned to appear as Marsh believed it should, which meant it had too few vertebrae. In addition, a sculpted model of what the museum felt the skull of this massive creature might have looked like was placed on the skeleton. This was not a delicate skull like that of Diplodocus, which would later turn out to be more accurate, but was based on "the biggest, thickest, strongest skull bones, lower jaws, and tooth crowns from three different quarries". These skulls were likely those of Camarasaurus, the only other sauropod of which good skull material was known at the time. The mount construction was overseen by Adam Hermann, who failed to find Brontosaurus skulls. Hermann was forced to sculpt a stand-in skull by hand. Henry Fairfield Osborn noted in a publication that the skull was "largely conjectural and based on that of Morosaurus" (now Camarasaurus). On October 20, 1979, after the publications by McIntosh and Berman, the first skull of an Apatosaurus was mounted on a skeleton in a museum, that of the Carnegie. Another specimen of an Apatosaurine now referred to Brontosaurus was discovered in 1993 by the Tate Geological Museum, also from the Morrison Formation of central Wyoming. The specimen consisted of a partial postcranial skeleton, including a complete manus and multiple vertebrae, and was described by James Filla and Pat Redman a year later. Despite this, at least one paleontologist—Robert T. Bakker—argued in the 1990s that A. ajax and A. excelsus are sufficiently distinct that the latter continues to merit a separate genus. In 2015, an extensive study of diplodocid relationships by Emanuel Tschopp, Octavio Mateus, and Roger Benson concluded that Brontosaurus was indeed a valid genus of sauropod distinct from Apatosaurus. The scientists developed a statistical method to more objectively assess differences between fossil genera and species and concluded that Brontosaurus could be "resurrected" as a valid name. They assigned two former Apatosaurus species, A. parvus, and A. yahnahpin, to Brontosaurus, as well as the type species B. excelsus. Donald Prothero, who criticized the mass media reaction to this study as superficial and premature, and many others below. Some paleontologists, such as John and ReBecca Foster, continue to consider Brontosaurus as a synonym of Apatosaurus. ==Description==

(orange), A. louisae (red), and Brontosaurus parvus'' (green) Brontosaurus was a large, long-necked, quadrupedal animal with a long, whip-like tail, and forelimbs that were slightly shorter than its hindlimbs. The largest species, B. excelsus, measured up to long from head to tail and weighed up to ; other species were smaller, measuring long and weighing . Skull and vertebrae Although the skull of Brontosaurus has not been found, it was probably similar to the skull of the closely related Apatosaurus. Several skulls of Apatosaurus have been found, all of which are very small in proportion to the body. Their snouts were squared off and low, in contrast to those of macronarians. The spine and tail consisted of 15 cervicals, ten dorsals, five sacrals, and about 82 caudals, based on Apatosaurus. The number of caudal vertebrae has been noted to vary, even within a species. Vertebrae in the neck, torso, and sacrum of sauropods bore large pneumatic foramina on their lateral sides. Similar structures are observable in birds and large mammals. The cervical vertebrae were stouter than those of other diplodocids, as in Apatosaurus. On the lateral sides of the cervicals, apatosaurines had well-developed and thick parapophyses (extensions on the lateral sides of the vertebrae that attached to cervical ribs) which would point ventrally under the centrum. These parapophyses in conjunction with dense diapophyses and cervical ribs were strong anchors for neck muscles, which could sustain extreme force. The cervicals were also more boxy than in other sauropods due to their truncated zygapophyses and tall build. Neural canals, which contain the spinal cord of the vertebral column, are ovate and large in the dorsals. The diapophyses protrude outward and curve downward in a hook-shape. Neural spines are thick in anterior-posterior view with a bifurcate top. Ten dorsal ribs are on either side of the body. Limbs Several scapulae are known from Brontosaurus, all of which are long and thin with relatively elongated shafts. with the humerus resembling that of Camarasaurus, and those of B. excelsus being nearly identical to those of Apatosaurus ajax. The humerus had a thin bone shaft and larger transverse ends. Its anterior end bears a large deltopectoral crest, which was on the extremities of the bone. Charles Gilmore in 1936 noted that previous reconstructions erroneously proposed that the radius and ulna could cross, when in life they would have remained parallel. Even by 1936, it was recognized that no sauropod had more than one hand claw preserved, and this one claw is now accepted as the maximum number throughout the entire group. The metacarpals are elongated and thinner than the phalanges, bearing boxy articular ends on its proximal and distal faces. The single front claw bone is slightly curved and squarely shortened on the front end. The phalangeal formula is 2-1-1-1-1, meaning the innermost finger (phalanx) on the forelimb has two bones and the next has one. The single manual claw bone (ungual) is slightly curved and squarely truncated on the anterior end. Proportions of the manus bones vary within Apatosaurinae as well, with B. yahnahpins ratio of longest metacarpal to radius length around 0.40 or greater compared to a lower value in Apatosaurus louisae. The femora of Brontosaurus are very stout and represent some of the most robust femora of any member of Sauropoda. The tibia and fibula bones are different from the slender bones of Diplodocus but are nearly indistinguishable from those of Camarasaurus. The fibula is longer and slenderer than the tibia. The foot of Brontosaurus has three claws on the innermost digits; the digit formula is 3-4-5-3-2. The first metatarsal is the stoutest, a feature shared among diplodocids. B. excelsuss astragalus differs from other species in that it lacks a laterally directed ventral shelf. ==Classification==

Brontosaurus is a member of the family Diplodocidae, a clade of gigantic sauropod dinosaurs. The family includes some of the longest and largest creatures ever to walk the earth, including Diplodocus, Supersaurus, and Barosaurus. Diplodocids first evolved during the Middle Jurassic in what is now Georgia, spreading to North America during the Late Jurassic. Brontosaurus is classified in the subfamily Apatosaurinae, which also includes Apatosaurus and possibly one or more unnamed genera. In 1878, Marsh raised his family to the rank of suborder, including Apatosaurus, Brontosaurus, Atlantosaurus, Morosaurus (=Camarasaurus), and Diplodocus. He classified this group within Sauropoda. In 1903, Elmer S. Riggs mentioned that the name Sauropoda would be a junior synonym of earlier names, and grouped Apatosaurus within Opisthocoelia. Most authors still use Sauropoda as the group name. Originally named by its discoverer Othniel Charles Marsh in 1879, Brontosaurus had long been considered a junior synonym of Apatosaurus; its type species, Brontosaurus excelsus, was reclassified as A. excelsus in 1903. However, an extensive study published in 2015 by a joint British-Portuguese research team concluded that Brontosaurus was a valid genus of sauropod distinct from Apatosaurus. Nevertheless, not all paleontologists agree with this division. It grew up to long. It was described by James Filla and Patrick Redman in 1994 as a species of Apatosaurus (A. yahnahpin). The specific name is derived from Lakota mah-koo yah-nah-pin, "breast necklace", a reference to the pairs of sternal ribs that resemble the hair pipes traditionally worn by the tribe. The holotype specimen is TATE-001, a relatively complete postcranial skeleton found in the lower Morrison Formation of Wyoming. More fragmentary remains have also been referred to the species. A re-evaluation by Robert T. Bakker in 1998 found it to be more primitive, so Bakker coined the new generic name Eobrontosaurus, derived from Greek , "dawn", and Brontosaurus. The cladogram below is the result of an analysis by Tschopp, Mateus, and Benson (2015). The authors analyzed most diplodocid type specimens separately to deduce which specimen belonged to which species and genus. }} ==Paleobiology==

When Brontosaurus was described in 1879, the widespread notion in the scientific community was that sauropods were semi-aquatic, lethargic reptiles that were inactive. Various uses for the single claw on the forelimb of sauropods have been proposed. One suggestion is that they were used for defense, but their shape and size make this unlikely. It was also possible they were for foraging, but the most probable use for the claw was grasping objects such as tree trunks when rearing. The slow locomotion of sauropods may be due to the minimal muscling or recoil after strides. A possible bipedal trackway of a juvenile Apatosaurus is known, but it is disputed if it was possible for the sauropod. Diet and energy requirements Being a diplodocid sauropod, Brontosaurus was herbivorous and fed on ferns, cycadeoids, seed ferns, and horsetails, eating at ground height as a nonselective browser. The replacement method and physiology of Apatosauruss teeth is unique, with the entire tooth row being replaced at once and up to 60% more often than Diplodocus. The teeth of Apatosaurus are thick, lack denticles, and are strongly cylindrical in cross-section whereas they are long, slender, and elliptical in cross-section in Diplodocus. These characteristics imply that Apatosaurus, and likely Brontosaurus, consumed tougher vegetation than Diplodocus. Hypotheses of the food requirements of Brontosaurus have been made, though predicting this is difficult due to the lack of modern analogues. Endotherms (mammals) and ectotherms (reptiles) require a specific amount of nutrition to survive which correlates with their metabolism as well as body size. Estimations of the dietary necessities of Brontosaurus were made in 2010, with a guess of 2•10^4 to 50•10^4 kilojoules needed daily. This led to hypotheses on the distributions of Brontosaurus to meet this requirement, though they varied on whether it was an ectotherm or endotherm. If Brontosaurus was an endotherm, fewer adult individuals could be sustained than if it were an ectotherm, which could have tens of animals per square kilometer. Due to this, it has been theorized that Brontosaurus and other sauropods living within the arid environment of the Morrison Formation participated in migrations between feeding sites. Assuming Apatosaurus had an avian respiratory system and a reptilian resting-metabolism, Frank Paladino etal. (1997) estimate the animal would have needed to consume only about of water per day. Posture Historically, sauropods like Brontosaurus were believed to have been too massive to support their weight on dry land, so theoretically, they must have lived partly submerged in water, perhaps in swamps. Recent findings do not support this, and sauropods are thought to have been fully terrestrial animals. Diplodocids like Brontosaurus are often portrayed with their necks held high up in the air, allowing them to browse on tall trees. Though some studies have suggested that diplodocid necks were less flexible than previously believed, other studies have found that all tetrapods appear to hold their necks at the maximum possible vertical extension when in a normal, alert posture, and argue that the same would hold true for sauropods barring any unknown, unique characteristics that set the soft tissue anatomy of their necks apart from that of other animals. Physiology James Spotila et al. (1991) suggest that the large body size of Brontosaurus and other sauropods would have made them unable to maintain high metabolic rates, as they would not be able to release enough heat. However, temperatures in the Jurassic were 3 degrees Celsius higher than present. Furthermore, they assumed that the animals had a reptilian respiratory system. Matt Wedel found that an avian system would have allowed them to dump more heat. Some scientists have also argued that the heart would have had trouble sustaining sufficient blood pressure to oxygenate the brain. In 2008, a study on the growth rates of sauropods was published by biologists Thomas Lehman and Holly Woodward. They said that by using growth lines and length-to-mass ratios, Apatosaurus would have grown to 25t (25 long tons; 28 short tons) in 15years, with growth peaking at in a single year. An alternative method, using limb length and body mass, found Brontosaurus and Apatosaurus grew per year, and reached their full mass before it was about 70years old. These estimates have been called unreliable because the calculation methods are not sound; old growth lines would have been obliterated by bone remodeling. One of the first identified growth factors of Apatosaurus was the number of sacral vertebrae, which increased to five by the time of the creature's maturity. This was first noted in 1903 and again in 1936. Tail The estimated tail length of Brontosaurus is approximately 56% of the total body length, with the tail sometimes hypothesized to be capable of functioning like a very long, tapering bullwhip. There is some circumstantial evidence supporting this as well: a number of diplodocids have been found with fused or damaged tail vertebrae, which may be a symptom of cracking their tails: these are particularly common between the 18th and the 25th caudal vertebra, a region the authors consider a transitional zone between the stiff muscular base and the flexible whiplike section. However, Rega (2012) notes that Camarasaurus while lacking a tailwhip, displays a similar level of caudal co-ossification and that Mamenchisaurus while having the same pattern of vertebral metrics, lacks a tailwhip and does not display fusion in any "transitional region". Also, the crush fractures which would be expected if the tail was used as a whip have never been found in diplodocids. More recently, Baron (2020) has considered the use of the tail as a bullwhip unlikely because of the potentially catastrophic muscle and skeletal damage such speeds could cause on the large and heavy tail. Instead, he proposes that the tails might have been used as a tactile organ to keep in touch with the individuals behind and to the sides of the animal in a group, which could have augmented cohesion and allowed communication among individuals while limiting more energetically demanding activities like stopping to search for dispersed individuals, turning to visually check on others behind, or communicating vocally. Neck combat of B. excelsus, showing its robusticity The cervical vertebrae of Brontosaurus and Apatosaurus are robust, which has led to speculation on the use of these structures. These structures had expensive energy requirements, so the reason for their evolution must have been important to the animal. Notable features include dense cervical ribs and diapophyses, ribs that are angled ventrally, and an overall subtriangular cross-section. These traits are in contrast to the more fragile cervicals of diplodocines. Cervical ribs acted as anchors for the longus colli ventralis and flexer colli lateralis muscles, which are used in the downward motion of the neck. Stronger muscles for ventral motions allowed more force to be exerted downward. The cervical ribs formed a "V"-shape, which could be used to shelter the softer underlying tissues of the neck from damage. Ventral sides of the cervical ribs were capped by round, protruding processes. These have been suggested to have been attachment points for bosses or keratinous spikes. A preprint by Wedel et al (2015) thought that due to the combination of these traits, Brontosaurus would use its neck for combat between individuals through the use of striking necks. Behavior like this has been observed in other animals like giraffes and large tortoises. == Paleoecology ==

mounted as if feeding on a Brontosaurus'' carcass, AMNH The Morrison Formation is a sequence of shallow marine and alluvial sediments which, according to radiometric dating, ranges between 156.3 million years old (Mya) at its base, and 146.8 Mya at the top, which places it in the late Oxfordian, Kimmeridgian, and early Tithonian stages of the Late Jurassic period. This formation is interpreted as a semi-arid environment with distinct wet and dry seasons. The Morrison Basin, where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan and was formed when the precursors to the Front Range of the Rocky Mountains started pushing up to the west. The deposits from their east-facing drainage basins were carried by streams and rivers and deposited in swampy lowlands, lakes, river channels, and floodplains. This formation is similar in age to the Lourinhã Formation in Portugal and the Tendaguru Formation in Tanzania. Brontosaurus may have been a more solitary animal than other Morrison Formation dinosaurs. As a genus, Brontosaurus existed for a long interval, and was found in most levels of the Morrison. B. excelsus fossils have been reported from only the Brushy Basin Member, dating to the late Kimmeridgian age, about 151 Mya. Dinosaurs known from the Morrison include the theropods Ceratosaurus, Ornitholestes, and Allosaurus, the sauropods Apatosaurus, Brachiosaurus, Camarasaurus, and Diplodocus, and the ornithischians Camptosaurus, Dryosaurus, and Stegosaurus. Other vertebrates that shared this paleoenvironment included ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphs, and several species of pterosaurs. Shells of bivalves and aquatic snails, are also common. The flora of the period has been revealed by fossils of green algae, mosses, horsetails, cycads, ginkgoes, and several families of conifers. Vegetation varied from river-lining forests of tree ferns and ferns (gallery forests), to fern savannas with occasional trees such as the Araucaria-like conifer Brachyphyllum. ==In popular culture==

of B. excelsus submerged in water, and Diplodocus dragging its tail The length of time taken for Riggs's 1903 reclassification of Brontosaurus as Apatosaurus to be brought to public notice, as well as Osborn's insistence that the Brontosaurus name be retained despite Riggs's paper, meant that Brontosaurus became one of the most famous dinosaurs. Brontosaurus has often been depicted in cinema, beginning with Winsor McCay's 1914 classic Gertie the Dinosaur, one of the first animated films. McCay based his unidentified dinosaur on the apatosaurine skeleton in the American Museum of Natural History. The 1925 silent film The Lost World featured a battle between a Brontosaurus and an Allosaurus, using special effects by Willis O'Brien. The 1933 film King Kong featured a Brontosaurus chasing Carl Denham, Jack Driscoll and the terrified sailors on Skull Island. In 1938 the assembling of a Brontosaurus skeleton was a major plot point in the Katharine Hepburn and Cary Grant film Bringing Up Baby. These, and other early uses of the animal as a major representative of the group, helped cement Brontosaurus as a quintessential dinosaur in the public consciousness. Sinclair Oil Corporation has long been a fixture of American roads (and briefly in other countries) with its green dinosaur logo and mascot, a Brontosaurus. While Sinclair's early advertising included a number of different dinosaurs, eventually only Brontosaurus was used as the official logo, due to its popular appeal. As late as 1989, the U.S. Postal Service faced controversy when it issued four "dinosaur" stamps: Tyrannosaurus, Stegosaurus, Pteranodon, and Brontosaurus. The use of the term Brontosaurus in place of Apatosaurus led to complaints of "fostering scientific illiteracy." The Postal Service defended itself (in Postal Bulletin 21742) by saying, "Although now recognized by the scientific community as Apatosaurus, the name Brontosaurus was used for the stamp because it is more familiar to the general population." Indeed, the Postal Service even implicitly rebuked the somewhat inconsistent complaints by adding that "[s]imilarly, the term 'dinosaur' has been used generically to describe all the animals [i.e., all four of the animals represented in the given stamp set], even though the Pteranodon was a flying reptile [rather than a true 'dinosaur']," a distinction left unmentioned in the numerous correspondence regarding the Brontosaurus/Apatosaurus issue. Palaeontologist Stephen Jay Gould supported this position. In the essay from which the title of the 1991 collection Bully for Brontosaurus is taken, Gould wrote: "Touché and right on; no one bitched about Pteranodon, and that's a real error." being described by AllMusic as one that "uncovers the sensitivity of someone seemingly impervious in a tale that resembles Dumbo as a depressed dinosaur". news staff, and personal blog nature (both related and not), from both sides of the debate, from related and unrelated contexts, and from all over the world. Since Wedel et al 2015 preprint, ==References==