Temporal range: Late Jurassic, 154–150Ma
|Mounted A. louisae holotype specimen CMNH 3018, Carnegie Museum of Natural History|
Apatosaurus (meaning "deceptive reptile" //) is an extinct genus of sauropod dinosaur that lived in North America during the Late Jurassic period. The genus was first described in 1877 when Othniel Charles Marsh named A. ajax, and many species have since been described. They range in age from about 154 to 150 million years ago throughout the Kimmeridgian and early Tithonian ages of the Morrison Formation. Brontosaurus is now considered a junior synonym of Apatosaurus, its only species being renamed A. excelsus. It had an average length of 22.8 m (75 ft) and a mass of at least 16.4 metric tons (18.1 short tons), although a few specimens indicate a length up to 30% greater and a weight of 33–73 t (32–72 long tons; 36–80 short tons).
The cervical vertebrae were less elongated and more heavily constructed than those of Diplodocus and the bones of the leg were much stockier despite being longer, implying that Apatosaurus was a more robust animal. The tail was held above the ground during normal locomotion. Like all sauropods, Apatosaurus had only one claw on the forelimbs and three on its hindlimbs. The skull of Apatosaurus, long thought to be similar to Camarasaurus, is much more similar to that of Diplodocus. Apatosaurus was a generalized browser, likely holding its head elevated, and may have grown 520 kilograms (1,150 pounds) per year until it reached 70 years of age. To lighten its bones, Apatosaurus had air sacs, which made the inside of bones sponge-like and full of holes. its tail, like that of other diplodocids, may have been used as a whip, creating loud noise.
Apatosaurus is a genus in the family Diplodocidae. It is more basal than other genera like Diplodocus and Barosaurus, and is sometimes included in its own subfamily, Apatosaurinae. Apatosaurus is one of the more common sauropods in the Morrison Formation, and is often found associated with skeletons of Allosaurus, Camarasaurus, Stegosaurus and Diplodocus. Apatosaurus is also one of the longest Morrison dinosaurs, although Supersaurus exceeds it.
Apatosaurus was a large, long-necked quadrupedal animal with a long, whip-like tail. Its forelimbs were slightly shorter than its hindlimbs. Most size estimates are based on specimen CM 3018 (the type specimen of A. louisae), which reached 21–22.8 m (69–75 ft) in length and 16.4–22.4 t (16–22 long tons; 18–25 short tons) in weight, though past estimates have been as high as 35 t (34 long tons; 39 short tons). One of the first estimates of A. louisae was found to be 21.8 m (72 ft), found by measuring the vertebral column. Undescribed specimens like OMNH 1670 represent individuals 11-30% longer, suggesting weights double that of CM 3018 or 33–73 t (32–72 long tons; 36–80 short tons), potentially rivalling the largest titanosaurs.
The skull was small in comparison with the size of the animal. The jaws were lined with spatulate (chisel-like) teeth that were suited to a herbivorous diet. The snout of Apatosaurus and similar diplodocoids are squared, with only Nigersaurus having a squarer skull. The braincase of Apatosaurus is well preserved in specimen BYU 17096. The bones are articulated, and their fusion indicates that the bones are mature. The braincase was placed in a phylogenetic analysis, and its morphology was found to be very similar to that of other diplodocoids. Some skulls of Apatosaurus have been found still in articulation with their teeth. Those teeth that have the enamel surface exposed do not have any scratches on the surface, and instead display a sugary texture and little wear.
Like those of other sauropods, the vertebrae of the neck were deeply bifurcated; that is, they carried paired spines, resulting in a wide and deep neck. The vertebral formula was: 15 cervicals, 10 dorsals, 5 sacrals, and 82 caudals. The caudal vertebra number was noted to differ individually, even within a species. The cervical vertebrae were stouter than other diplodocids, and found to be most similar to Camarasaurus by Charles Whitney Gilmore. The Atlas-Axis complex of the first cervicals is nearly fused in Apatosaurus louisae. The dorsal ribs are not fused or tightly attached to their vertebrae, instead being loosely articulated. There are ten dorsal ribs on either side of the body. The large neck was filled with an extensive system of weight-saving air sacs. Apatosaurus, like its close relative Supersaurus, has tall spines on its vertebrae, which make up more than half the height of the individual bones. The shape of the tail is unusual for a diplodocid, being comparatively slender, due to the vertebral spines rapidly decreasing in height the farther they are from the hips. Apatosaurus also had very long ribs compared to most other diplodocids, giving it an unusually deep chest. As in other diplodocids, the last portion of the tail of Apatosaurus possessed a whip-like structure.
The limb bones were also very robust. Within the genus, the scapula of A. louisae is intermediate in morphology between those of A. ajax and A. excelsus. The arm bones are stout, with the humerus resembling that of Camarasaurus, and those of A. excelsus and A. ajax being nearly identical. 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. Apatosaurus had a single large claw on each forelimb, and the first three toes possessed claws on each hindlimb. The phalangeal formula is 2-1-1-1-1, meaning that the innermost finger (phalange) on the forelimb has two bones, the next has one, etc. Even by 1936 it was recognized that no sauropod manus preserved more than one claw, a feature currently recognised for the entire group. The single manual ungual is slightly curved, and squarely truncated on the anterior end. The pelvic girdle includes the robust ilia, and the coosified pubes and ischia. The femora of A. louisae are the stoutest of any member of Sauropoda. Rugosities are present on both ends of the femur, and the top end protrudes above the great trochanter. The tibia and fibula bones are nearly indistinguishable from those of Camarasaurus, although they are different from the slender bones of Diplodocus. The fibula is longer than the tibia, although it is also more slender. The foot of Apatosaurus has three claws on the innermost digits, and the digit formula is 3-4-5-3-2. In an individual of A. louisae, the astragalus was not found fused to the tibia. The stoutest metatarsal is in digit 1, and the third metatarsal is the second stoutest.
Apatosaurus is a member of the family Diplodocidae, a clade of gigantic sauropod dinosaurs. The family includes some of the longest creatures ever to walk the earth, including Diplodocus, Supersaurus, and Barosaurus. Apatosaurus is sometimes classified in the subfamily Apatosaurinae, which may also include Suuwassea, Supersaurus and Eobrontosaurus. Othniel Charles Marsh described Apatosaurus as being allied to Atlantosaurus, within the now defunct group Atlantosauridae. In 1878, Marsh raised his family to the rank of suborder, including Apatosaurus, 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. John Whitlock published a study in 2011 placing Apatosaurus as the most basal diplodocid, a placement that is often supported.
Discovery and species
Marsh, a Professor of Paleontology at Yale University, described and named an incomplete (and juvenile) skeleton of Apatosaurus ajax in 1877. The composite term Apatosaurus comes from the Greek words apate (ἀπάτη)/apatelos (ἀπατηλός) meaning "deception"/"deceptive" and sauros (σαῦρος) meaning "lizard"; thus, "deceptive lizard". Marsh gave it this name based on the chevron bones, which were dissimilar to those of other dinosaurs and instead possessed similarities with mosasaur chevrons. Two years later, Marsh announced the discovery of a larger and more complete specimen at Como Bluff Wyoming—which, because of discrepancies including the size difference, he identified as belonging to an entirely new genus and species. He named the new species Brontosaurus excelsus, meaning "thunder lizard", from the Greek brontē/βροντη meaning "thunder" and sauros/σαυρος meaning "lizard", and from the Latin excelsus, "noble" or "high". All Apatosaurus specimens are from the Morrison Formation. In 1877 this formation became the center of the Bone Wars, a fossil-collecting rivalry between early paleontologists Othniel Charles Marsh and Edward Drinker Cope. It is for this reason that the publications and descriptions of taxa by Marsh and Cope were rushed at the time.
Elmer Riggs in the 1903 edition of Geological Series of the Field Columbian Museum argued that Brontosaurus was not different enough from Apatosaurus to warrant its own genus, and created the combination Apatosaurus excelsus. Riggs stated that "In view of these facts the two genera may be regarded as synonymous. As the term 'Apatosaurus' has priority, 'Brontosaurus' will be regarded as a synonym". Nonetheless, before the mounting of the American Museum of Natural History Apatosaurus, Henry Fairfield Osborn chose to label the skeleton "Brontosaurus", even though he was a strong opposer of Marsh and his taxa.
The AMNH specimen (now assigned to A. ajax) is very complete, only missing the head, feet and sections of the tail, as was the first sauropod skeleton mounted. To complete the mount, sauropod feet that were discovered at the same quarry were added, as well as a tail fashioned to appear as Marsh believed it should, which had too few vertebrae. In addition, a sculpted model of what the museum felt the skull of this massive creature might look like. 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 for which good skull material was known at the time. The mount construction was overseen by Adam Hermann, who failed to find Apatosaurus 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).
In 1903 Riggs also described a new specimen of Apatosaurus, which was then placed in the collections of the Field Columbian Museum. Found near the Grand River Valley of Fruita, Colorado, the last cervical vertebrae were exposed from the hillside. Those cervicals were articulated with the thoracic vertebrae, which were excavated from the slope. Ten feet downhill, the distal end of a femur could be seen in the matrix. The rocks were so hard that drills and dynamite had to be used to extract the specimen. Nearly the entire rear of the skeleton was uncovered, measuring 5.5 m (18 ft). Apparently when first preserved, the entire skeleton was present, but the cervical vertebrae and forelimbs were eroded away.
The skull, from the Carnegie Quarry expeditions by Earl Douglass, was found a few meters away from a skeleton identified as Apatosaurus, soon named A. louisae, after Andrew Carnegie's wife Louise. The skull was designated as CM 11162, and bore a very similar morphology to skulls of Diplodocus. It was accepted as belonging to the Apatosaurus by Douglass and Carnegie Museum director William H. Holland, although the scientific consensus was that it was of a different genus. Holland defended his view in 1914 in an address to the Paleontological Society of America, yet he left the museum mount headless. While some thought Holland was attempting to avoid conflict with Osborn, Keith Parsons suspected that Holland was waiting until an articulated skull and neck were found to confirm the association of the skull and skeleton. After Holland's death in 1934, a cast of a Camarasaurus skull ended up being placed on the mount.
At the Yale Peabody Museum, a skeleton was mounted in 1931 with a skull unique from all the others. While at the time most museums were using Camarasaurus casts, the Peabody Museum sculpted a completely different skull. They based the lower jaw on a Camarasaurus mandible, with the cranium resembling Marsh's 1891 illustration. The skull also included forward-pointing nasals, something truly different to any dinosaur, and fenestrae differing from the drawing and other skulls.
No Apatosaurus skull was mentioned in literature until the 1970s when John Stanton McIntosh and David Berman redescribed the skulls of Diplodocus and Apatosaurus. They found that though he never published his opinion, Holland was almost certainly correct, that Apatosaurus had a Diplodocus like skull. According to them, many skulls long thought to pertain to Diplodocus might instead be those of Apatosaurus. They reassigned multiple skulls to Apatosaurus based on associated and closely associated vertebrae. Even though they supported Holland, it was noted that Apatosaurus might have possessed a Camarasaurus like skull, based on a disarticulated Camarasaurus-like tooth found at the precise site where an Apatosaurus specimen was found years before. On October 20, 1979, after the publications by McIntosh and Berman, the first true skull of Apatosaurus was mounted on a skeleton in a museum, that of the Carnegie. In 1998, the Felch Quarry skull that Marsh included in his 1896 skeletal restoration was suggested to belong to Brachiosaurus instead. In 2011, a unique Apatosaurus specimen was first described. This specimen, CMC VP 7180, was the first specimen of Apatosaurus where a skull was found articulated with its cervical vertebrae. The specimen was found to differ in both cranial and cervical features from A. louisae, and the specimen was found to have a majority of features related to those of A. ajax.
Almost all modern paleontologists have agreed with Riggs that the two species should be classified together in a single genus. According to the rules of the ICZN (which governs the scientific names of animals), the name Apatosaurus, having been published first, has priority as the official name; Brontosaurus is considered a junior synonym and has therefore been discarded from formal use. Despite this, at least one paleontologist—Robert T. Bakker—argued in the 1990s that A. ajax and A. excelsus are in fact sufficiently distinct that the latter continues to merit a separate genus.
Multiple species of Apatosaurus and its synonyms have been designated from scant material. Marsh named as many species as he could, which resulted in many being based upon fragmentary and indistinguishable remains. In 2005, Paul Upchurch and colleagues authored a study published to analyze the species and specimen relationships of Apatosaurus.
- Apatosaurus ajax was named by Marsh in 1877 after Ajax, the hero from Greek mythology. Marsh designated the fairly complete skeleton YPM 1860 as its holotype. The species remained largely unknown as it was overshadowed by A. excelsus and A. louisae. In 2005, many specimens in addition to the holotype were found assignable to A. ajax, YPM 1840, NSMT-PV 20375, YPM 1861, and AMNH 460. The specimens span from the late Kimmeridgian to the early Tithonian. A. ajax is the senior synonym of Atlantosaurus immanis and Apatosaurus laticoliis.
- Apatosaurus excelsus was first named by Marsh in 1890 under the genus Brontosaurus. Many specimens, including the holotype YPM 1980, have been assigned to the species. They include FMNH P25112, UWGM 15556, and CMNH 566. In a 2005 revision of Apatosaurus, the Field Museum specimen was found to represent an intermediate species, and the University of Wyoming and Carnegie Museum specimens were reassigned to A. parvus. Apatosaurus amplus, occasionally assigned to A. parvus, is a junior synonym of A. excelsus. A. excelsus as of yet only includes its type specimen and the type specimen of A. amplus.
- Apatosaurus louisae was named by Holland in 1916 in honor of Mrs. Louise Carnegie, wife of Andrew Carnegie who funded field research to find complete dinosaur skeletons in the American West. Apatosaurus louisae was first known from one partial skeleton which was found in Utah in the United States. The holotype is CMNH 3018, with referred specimens including CMNH 3378, CMNH 11162, and LACM 52844. The former two consist of a vertebral column, the latter two a skull and a nearly complete skeleton, respectively. A. louisae is one of the most distinct species, yet it was recovered as the most primitive species in the Upchurch phylogeny. Its specimens all come from the late Kimmeridgian of Dinosaur National Monument.
- Apatosaurus parvus, first described as Elosaurus in 1902 by Peterson and Gilmore, was reassigned to Apatosaurus in 1994, with the synonymy being upheld in 2005. The specimens include the holotype, CMNH 566, a partial skeleton of a possible juvenile, the scapula OMNH 1300, and the postcranial skeleton UWGM 155656, the latter two previously considered A. excelsus. It is the oldest species in the genus, from the middle Kimmeridgian.
The 2005 paper by Upchurch and colleagues on the species-level taxonomy of Apatosaurus contained a cladogram of 11 specimens of Apatosaurus finding many referable to A. ajax and few to A. parvus, A. excelsus, and A. louisae. The results are shown below:
- Apatosaurus grandis was named in 1877 by Marsh in the article that described A. ajax. It was briefly described, figured, and diagnosed. Marsh noted that it was only provisionally assigned to the genus when he reassigned it to his new genus Morosaurus in 1878. It is now the oldest species of Camarasaurus, after being reassigned to that genus.
- Apatosaurus minimus was described originally as a specimen of Brontosaurus sp. in 1904 by Osborn. In 1917, it was named as its own species, A. minimus, by Henry Mook for a pair of ilia and their sacrum. In 2012, Mike P. Taylor and Matt J. Wedel published a short abstract describing the material of "A." minimus, finding it to be hard to place among either Diplodocoidea or Macronaria. While it was placed with Saltasaurus in a phylogenetic analysis, it was thought to represent instead some form with convergent features from many groups.
- Apatosaurus alenquerensis was named in 1957 by Albert-Félix de Lapparent and Georges Zbyweski. It was based on postcrania from Portugal. In 1990 this was referred to Camarasaurus, but in 1998 it was given its own genus, Lourinhasaurus.
- Apatosaurus yahnahpin was named by James Filla and Patrick Redman in 1994. Bakker made A. yahnahpin the type species of a new genus, Eobrontosaurus in 1998, so it is now properly Eobrontosaurus yahnahpin. One partial skeleton has been found in Wyoming. It has been argued that Eobrontosaurus belongs within Camarasaurus, although this has been disputed.
It was historically believed that sauropods like Apatosaurus were too massive to support their own weight on dry land, so it was theorized that 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.
A study of diplodocid snouts showed that the square snout, large proportion of pits, and fine subparallel scratches in Apatosaurus suggests it was a ground-height nonselective browser. It may have eaten ferns, cycadeoids, seed ferns, horsetails, and algae. Kent Stevens and Michael Parrish (1999 and 2005) suggest that Apatosaurus had a great feeding range as its neck could bend into a U-shape laterally. The neck's range of movement would have also allowed the head to graze below the level of the body, leading some scientists to speculate on whether these sauropods grazed from riverbanks on submerged water plants.
Matthew Cobley et al. (2013) disputed this, finding that large muscles and cartilage would have limited movement of the neck. They state that the feeding ranges for sauropods like Diplodocus were smaller than previously believed and the animals may have had to move their whole bodies around to better access areas where they could browse vegetation. As such, they might have spent more time foraging to meet their minimum energy needs. The conclusions of Cobley et al. were disputed by Mike Taylor, who analysed the amount and positioning of intervertebral cartilage to determine the flexibility of the neck of Apatosaurus and Diplodocus. He found that the neck of Apatosaurus was very flexible.
In 1987, James Farlow calculated that an Apatosaurus-sized dinosaur about 35 t (34 long tons; 39 short tons) would have possessed 5.7 t (5.6 long tons; 6.3 short tons) of fermentation contents. Assuming Apatosaurus had an avian respiratory system and a reptilian resting-metabolism, Frank Paladino et al. (1997) estimate that the animal would need to consume only about 262 liters (69 gallons) of water per day.
Posture and locomotion
Diplodocids like Apatosaurus are often portrayed with their necks held high up in the air, allowing them to browse on tall trees. Some studies suggest that diplodocid necks were less flexible than previously believed, because the structure of the neck vertebrae would not have permitted the neck to bend far upwards, and that sauropods like Apatosaurus were adapted to low browsing or ground feeding. Other studies by Taylor find 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. Apatosaurus, like Diplodocus, would have held its neck angled upward with the head pointed downwards in a resting posture.
In 2008, footprints of a juvenile Apatosaurus were reported from Quarry Five in Morrison, Colorado. Discovered in 2006 by Matthew Mossbrucker, these footprints show that juveniles could run on their hind legs in a manner similar to that of the modern basilisk lizard. Trackways of Apatosaurus and other sauropods show that they walked an average of 30–40 km (19–25 mi) per day. A study found that they might have been able to walk 20–30 km (12–19 mi) per hour. The slow locomotion of sauropods may be due to the minimal muscling or recoil after strides.
Various uses have been proposed for the single claw on the forelimb of sauropods. It has been suggested that they were for defence, but the shape and size of them makes this unlikely. Other predictions were that it could be for feeding, but the most probable is that the claw was for grasping objects like tree trunks when rearing.
Given the large body mass of Apatosaurus, combined with its long neck, physiologists have encountered problems determining how these animals managed to breathe. Beginning with the assumption that Apatosaurus, like crocodilians, did not have a diaphragm, the dead-space volume (the amount of unused air remaining in the mouth, trachea and air tubes after each breath) has been estimated at about 0.184 m3 (184 l) for a 30 t (30 long tons; 33 short tons) specimen. Its tidal volume (the amount of air moved in or out during a single breath) has been calculated by Paladino to be 0.904 m3 (904 l) with an avian respiratory system, 0.225 m3 (225 l) if mammalian and 0.019 m3 (19 l) if reptilian.
On this basis, its respiratory system would likely have been parabronchi, with multiple pulmonary air sacs like in avian lungs and a flow-through lung. Furthermore, an avian system would need a lung volume of only about 0.60 m3 (600 l) compared to a mammalian requirement of 2.95 m3 (2,950 l), which would exceed the available space. The overall thoracic volume of Apatosaurus has been estimated at 1.7 m3 (1,700 l) allowing for a 0.50 m3 (500 l), four-chambered heart and a 0.90 m3 (900 l) lung capacity. That would allow about 0.30 m3 (300 l) for the necessary tissue. Evidence for the avian system in Apatosaurus and other sauropods is also in the pneumaticity of the vertebrae. Though this plays a role in reducing the weight of the animal, Wedel (2003) states that they also likely connected to air sacs as in birds.
James Spotila et al. (1991) suggest that the large body size of Apatosaurus and other sauropods would have made them unable to maintain high metabolic rates as they would not be able to release enough heat. They assumed that the animals had a reptilian respiratory system. Wedel found that an avian system would have allowed then to dump more heat. Some scientists have argued that the heart would have had trouble sustaining sufficient blood pressure to oxygenate the brain. Others argue that the near horizontal posture of the head and neck would have eliminated the problem of supplying blood to the brain, as it would not be elevated.
A 1999 microscopic study of Apatosaurus bones concluded that the animals grew rapidly when young and reached near-adult sizes in about 10 years. In 2008, a study on the growth rates for sauropods was published, authored by Thomas Lehman and Holly Woodward. They found that by using growth lines and length to mass, Apatosaurus would have attained a mass of 25 t (25 long tons; 28 short tons) in 15 years. This would imply sauropods had a growth rate of 5,000 kg (11,000 lb) per year. An alternative method, using limb length and body mass, found Apatosaurus to grow 520 kg (1,150 lb) per year until individuals reached an age of around 70. These estimates have been suggested to be unreliable as the methods producing them are not sound as old growth lines would have been obliterated due to bone remodelling. One of the first identified growth factors of Apatosaurus was the number of sacral vertebrae, which increased to five by maturity. This was first noted in 1903, and then again in 1936.
Long-bone histology enables researchers to estimate the age that a specific individual reached. A study by Eva Griebeler et al. (2013) examined long bone histological data and concluded that the Apatosaurus sp. SMA 0014 weighed 20,206 kg (22.3 short tons), reached sexual maturity at 21 years and died at age 28. The same growth model indicated that Apatosaurus sp. BYU 601–17328 weighed 18,178 kg (20.0 short tons), reached sexual maturity at 19 years and died at age 31.
An article that appeared in the November 1997 issue of Discover Magazine reported research into the mechanics of Apatosaurus tails by Nathan Myhrvold, a computer scientist from Microsoft. Myhrvold carried out a computer simulation of the tail, which in diplodocids like Apatosaurus was a very long, tapering structure resembling a bullwhip. This computer modeling suggested that sauropods were capable of producing a whip-like cracking sound of over 200 decibels, comparable to the volume of a cannon.
A pathology has also been identified on the tail of Apatosaurus, due to a growth defect. Two caudal vertebrae are seamlessly fused along the entire articulating surface of the bone, including the arches of the neural spines. This defect might have been caused due to the lack or inhibition of the substance that forms intervertebral disks or joints.
The Morrison Formation is a sequence of shallow marine and alluvial sediments which, according to radiometric dating, ranges between 156.3 million years old (Ma) at its base, to 146.8 million years old 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 semiarid 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 Lourinha Formation in Portugal and the Tendaguru Formation in Tanzania.
Apatosaurus was the second most common sauropod in the Morrison Formation ecosystem, after Camarasaurus. It may have been a more solitary animal than other Morrison Formation dinosaurs. Supersaurus has a greater total length and thus is the greatest of all sauropods from the Morrison. As a genus, Apatosaurus existed for a long span of time, and have been found in most levels of the Morrison. Fossils of Apatosaurus ajax are known exclusively from the upper portion of the formation (upper Brushy Basin Member), about 152–151 million years ago. A. excelsus fossils have been reported from the upper Salt Wash Member to the upper Brushy Basin Member, ranging from the middle to late Kimmeridgian age, about 154–151 million years ago. A. louisae fossils are rare, known only from one site in the upper Brushy Basin Member, dated to the late Kimmeridgian stage (about 151 million years ago). Additional Apatosaurus remains are known from even younger rocks, but they have not been identified as any particular species. Older Apatosaurus remains have also been identified from the middle Kimmeridgian, and are assigned to A. parvus. Fossils of these animals have been found in Nine Mile Quarry and Bone Cabin Quarry in Wyoming and at sites in Colorado, Oklahoma and Utah, present in stratigraphic zones 2–6.
The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs. Dinosaurs known from the Morrison include the theropods Ceratosaurus, Ornitholestes, and Torvosaurus, the sauropods Apatosaurus, Brachiosaurus, Camarasaurus, and Diplodocus, and the ornithischians Camptosaurus, Dryosaurus, and Stegosaurus. Apatosaurus is commonly found at the same sites as Allosaurus, Camarasaurus, Diplodocus, and Stegosaurus. Allosaurus accounted for 70 to 75% of theropod specimens and was at the top trophic level of the Morrison food web. Many of the dinosaurs of the Morrison Formation are the same genera as those seen in Portuguese rocks of the Lourinha Formation (mainly Allosaurus, Ceratosaurus, Torvosaurus, and Apatosaurus), or have a close counterpart (Brachiosaurus and Lusotitan, Camptosaurus and Draconyx). Other vertebrates that shared this paleoenvironment included ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans, and several species of pterosaur. Shells of bivalves and aquatic snails are also common. The flora of the period has been revealed by fossils of green algae, fungi, 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
The length of time taken for Marsh's misclassification to be brought to public notice meant that the name Brontosaurus, associated as it was with one of the largest dinosaurs, became so famous that it persisted long after the name had officially been abandoned in scientific use.
Apatosaurus have 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 Brontosaurus 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. These, and other early uses of the animal as 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, an Apatosaurus (Brontosaurus). While Sinclair's early advertising included a number of different dinosaurs, eventually only Apatosaurus was used as the official logo, due to its popular appeal.
As late as 1989, the U.S. Postal Service caused controversy when it issued four "dinosaur" stamps: Tyrannosaurus, Stegosaurus, Pteranodon and Brontosaurus. The use of the term Brontosaurus in place of Apatosaurus, as well as the fact that Pteranodons were technically pterosaurs and not dinosaurs, led to complaints of "fostering scientific illiteracy." The Postal Service defended itself (in Postal Bulletin 21744) 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." Palaeontologist Stephen Jay Gould also supported this position in his essay "Bully for Brontosaurus", though he echoed Riggs's original argument that Brontosaurus is a synonym for Apatosaurus. Nevertheless, he noted that the former has developed and continues to maintain an independent existence in the popular imagination.
- Seebacher, F. (2001). "A new method to calculate allometric length-mass relationships of dinosaurs". Journal of Vertebrate Paleontology 21 (1): 51–52. doi:10.1671/0272-4634(2001)021[0051:ANMTCA]2.0.CO;2. ISSN 0272-4634. JSTOR 4524171.
- Mazzetta, G.V.; Christiansen, P.; Farina, R.A. (2004). "Giants and bizarres: body size of some southern South American Cretaceous dinosaurs". Historical Biology 16 (2–4): 71–83. doi:10.1080/08912960410001715132. ISSN 1029-2381.
- Henderson, D.M. (2006). "Burly Gaits: Centers of mass, stability, and the trackways of sauropod dinosaurs". Journal of Vertebrae Paleontology 26 (4): 907–921. doi:10.1671/0272-4634(2006)26[907:BGCOMS]2.0.CO;2. JSTOR 4524642.
- Gilmore, C.W. (February 1936). "Osteology of Apatosaurus, with special references to specimens in the Carnegie Museum". Memoirs of the Carnegie Museum 11 (4): 1–136. OCLC 16777126.
- Wedel, M. (2013). "A giant, skeletally immature individual of Apatosaurus from the Morrison Formation of Oklahoma". 61st Symposium on Vertebrate Palaeontology and Comparative Anatomy Programme and Abstracts: 40–45.
- Fastovsky, D.E.; Weishampel, D.B. (2009). Dinosaurs: A Concise Natural History. Cambridge University Press. pp. 165–200. ISBN 978-0-521-88996-4.
- Whitlock, J.A. (2011). "Inferences of Diplodocoid (Sauropoda: Dinosauria) Feeding Behavior from Snout Shape and Microwear Analyses". PLOS ONE 6 (4): e18304. doi:10.1371/journal.pone.0018304.
- Balanoff, A.M.; Bever, G.S.; Ikejiri, T. (2010). "The Braincase of Apatosaurus (Dinosauria: Sauropoda) Based on Computed Tomography of a New Specimen with Comments on Variation and Evolution in Sauropod Neuroanatomy". American Museum Novitates 3677 (3677): 1–32. doi:10.1206/591.1.
- Riggs, E.S. (August 1903). "Structure and Relationships of Opisthocoelian Dinosaurs. Part I, Apatosaurus Marsh". Publications of the Field Columbian Museum Geographical Series 2 (4): 165–196. OCLC 494478078.
- Lovelace, D.M.; Hartman, S.A.; Wahl, W.R. (2007). "Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny". Arquivos do Museu Nacional 65 (4): 527–544. ISSN 0365-4508.
- Martin, A.J. (2006). Introduction to the Study of Dinosaurs (Second ed.). Blackwell Publishing. p. 560. ISBN 1-4051-3413-5.
- Upchurch, P. (1994). "Manus claw function in sauropod dinosaurs". Gaia 10: 161–171. ISSN 0871-5424.
- Taylor, M.P.; Naish, D. (2005). "The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)". PaleoBios 25 (2): 1–7.
- Harris, J.D. (2006). "The significance of Suuwassea emiliae (Dinosauria: Sauropoda) for flagellicaudatan intrarelationships and evolution". Journal of Systematic Palaeontology 4 (2): 185–198. doi:10.1017/S1477201906001805.
- Marsh, O.C. (December 1877). "Notice of New Dinosaurian Reptiles from the Jurassic formation". American Journal of Science 14 (84): 514–516.
- Upchurch, P.; Tomida, Y.; Barrett, P.M. (2005). "A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA". National Science Museum monographs 26 (118): 1–156. ISSN 1342-9574.
- Whitlock, J.A. (2011). "A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)". Zoological Journal of the Linnean Society 161 (4): 872–915. doi:10.1111/j.1096-3642.2010.00665.x.
- Gallina, P.A.; Apesteguía, S.; Haluza, A.; Canale, J.A. (2014). Farke, Andrew A., ed. "A Diplodocid Sauropod Survivor from the Early Cretaceous of South America". PLOS ONE 9 (5): e97128. doi:10.1371/journal.pone.0097128.
- Liddell, G.H.; Scott, R. (1882). A Greek-English Lexicon. Harper & Brothers. pp. 1–1774.
- Holtz, T.R. Jr. (2008). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House. pp. 1–432. ISBN 0-375-82419-7.
- Marsh, O.C. (1979). "Notice of new Jurassic dinosaurs". American Journal of Science 18: 501–505.
- Mahoney, K.D. (2015). "Latin Definitions for: excelsus (Latin search)". LatDict Latin Dictionary and Grammar Resources.
- Moon, B. (2010). "The Sauropod Dinosaurs of the Morrison Formation (Upper Jurassic, USA): A Review". Dinosauria: 1–9.
- Miller, B. (2014-10-30). "Bully for Camarasaurus". Dinosours.
- Parsons, K.M. (1997). "The Wrongheaded Dinosaur". Carnegie Magazine.
- Bakker, R.T. (1994). "The Bite of the Bronto". Earth 3 (6): 26–33.
- McIntosh, J.S.; Berman, D.S. (1975). "Description of the Palate and Lower Jaw of the Sauropod Dinosaur Diplodocus (Reptilia: Saurischia) with Remarks on the Nature of the Skull of Apatosaurus". Journal of Paleontology 49 (1): 187–199. JSTOR 1303324.
- Carpenter, Kenneth; Tidwell, Virginia (1998). "Preliminary Description of a Brachiosaurus Skull from Felch Quarry 1, Garden Park, Colorado". In Carpenter, Kenneth; Chure, Dan; Kirkland, James Ian. The Upper Jurassic Morrison Formation: an interdisciplinary study. Taylor & Francis. ISBN 978-90-5699-183-8.
- Barrett, P.M.; Storrs, G.W.; Young, M.T.; Witmer, L.M. (2011). "A new skull of Apatosaurus and its taxonomic and palaeobiological implications". Symposium of Vertebrate Palaeontology & Comparative Anatomy Abstracts of Presentations: 5.
- Taylor, M.P. (2010). "Sauropod dinosaur research: a historical review". Geological Society, London, Special Publications 343 (1): 361–386. doi:10.1144/SP343.22.
- Brinkman, P. (2006). "Bully for Apatosaurus". Endeavour 30 (4): 126–130. doi:10.1016/j.endeavour.2006.10.004. PMID 17097734.
- Upchurch, P.; Barrett, P.M.; Dodson, P. (2004). "Sauropoda". In Weishampel, D.B., Osmólska, H., and Dodson, P. The Dinosauria (2 ed.). University of California Press. pp. 259–322.
- McIntosh, J.S. (1995). A. Sun and Y. Wang, ed. "Remarks on the North American sauropod Apatosaurus Marsh". Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota Short Papers (China Ocean Press): 119–123.
- Bakker, R.T. (1998). "Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in Wyoming and Colorado". In Lucas, Spencer G.; Kirkland, James I.; Estep, J.W. Lower and Middle Cretaceous Terrestrial Ecosystems 14. New Mexico Museum of Natural History and Science Bulletin. pp. 67–77.
- Carpenter, Kenneth; Currie, P.J., eds. (1992). Dinosaur Systematics, Approaches and Perspectives. Cambridge University Press. pp. 1–318. ISBN 0-521-36672-0.
- Carpenter, K.; McIntosh, J. (1994). "Upper Jurassic sauropod babies from the Morrison Formation". In Carpenter, Kenneth; Hirsch, Karl F.; Horner, John R. Dinosaur Eggs and Babies. Cambridge University Press. pp. 265–278. ISBN 978-0-521-56723-7.
- Marsh, O.C. (1878). "Principal Characters of American Jurassic Dinosaurs". American Journal of Science 16 (95): 411–416.
- Foster, John (2007). Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 273–329. ISBN 978-0-253-34870-8.
- Taylor, M.P. (2012-07-27). ""Apatosaurus" minimus sacrum/ilia, right lateral view". Sauropod Vertebrae Picture of the Week.
- Taylor, M.P.; Wedel, M.J. (2012). "Re-evaluating "Apatosaurus" minimus, a bizarre Morrison Formation sauropod with diplodocoid and macronarian features". SVPCA 2012 Programme and Abstracts: 23.
- Hartman, S. (2005-02-13). ""Eobrontosaurus" is not Camarasaurus". Dinosaur Mailing List.
- Pierson, D.J. (2009). "The Physiology of Dinosaurs: Circulatory and Respiratory Function in the Largest Animals Ever to Walk the Earth". Respiratory Care 54 (7): 887–911. doi:10.4187/002013209793800286. PMID 19558740.
- Stevens, Kent A.; Parrish, JM (1999). "Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs". Science 284 (5415): 798–800. doi:10.1126/science.284.5415.798. PMID 10221910. Retrieved 2008-08-03.
- Stevens KA, Parrish JM (2005). "Neck Posture, Dentition and Feeding Strategies in Jurassic Sauropod Dinosaurs". In Carpenter, Kenneth and Tidswell, Virginia (ed.). Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press. pp. 212–232. ISBN 978-0-253-34542-4. OCLC 218768170 57202057 61128849.
- Cobley, Matthew J.; Rayfield, Emily J.; Barrett, Paul M. (2013). "Inter-Vertebral Flexibility of the Ostrich Neck: Implications for Estimating Sauropod Neck Flexibility". PLoS ONE 8 (8): e72187. doi:10.1371/journal.pone.0072187.
- Ghose, Tia (August 15, 2013). "Ouch! Long-Necked Dinosaurs Had Stiff Necks". livescience.com. Retrieved January 31, 2015.
- Taylor, M.P. (2014). "Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs". PeerJ 2: e712. doi:10.7717/peerj.712.
- Farlow, J.A. (1987). "Speculations About the Diet and Physiology of Herbivorous Dinosaurs". Paleobiology 13 (1): 60–72. JSTOR 2400838.
- Paladino, F.V.; Spotila, J.R., and Dodson, P. (1997). "A Blueprint for Giants: Modeling the Physiology of Large Dinosaurs". In Farlow, J.O. and Brett-Surman, M.K. The Complete Dinosaur. Indiana University Press. pp. 491–504. ISBN 0-253-33349-0.
- Upchurch, P et al. (2000). "Neck Posture of Sauropod Dinosaurs" (PDF). Science 287 (5453): 547b. doi:10.1126/science.287.5453.547b. Retrieved 2008-08-05.
- Taylor, M.P.; Wedel, M.J.; Naish, D. (2009). "Head and neck posture in sauropod dinosaurs inferred from extant animals". Acta Palaeontologica Polonica 54 (2): 213–220. doi:10.4202/app.2009.0007.
- Rajewski, Genevieve (May 2008). "Where Dinosaurs Roamed". Smithsonian: 20–24. Archived from the original on 27 April 2008. Retrieved 2008-04-30.
- Sellers, W.I.; Margetts, L.; Coria, R.A.; Manning, P.L. (2012). "March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs". PLOS ONE 8 (10): e78733. doi:10.1371/journal.pone.0078733.
- Wedel, M. J. (2003). "Vertebral Pneumaticity, Air Sacs, and the Physiology of Sauropod Dinosaurs". Paleobiology 29 (2): 243–255. doi:10.1666/0094-8373(2003)029<0243:vpasat>2.0.co;2. JSTOR 4096832.
- Spotila, J. R.; O'Connor, M. P.; Dodson, P. R.; Paladino, F. V. (1991). "Hot and cold running dinosaurs. Metabolism, body temperature, and migration". Modern Geology 16: 203–227.
- Curry, Kristina A. (1999). "Ontogenetic histology of Apatosaurus (Dinosauria: Sauropoda): new insights on growth rates and longevity". Journal of Vertebrate Paleontology 19 (4): 654–665. doi:10.1080/02724634.1999.10011179. JSTOR 4524036.
- Lehman, T.M.; Woodward, H.N. (2008). "Modelling growth rates for sauropod dinosaurs". Paleobiology 34 (2): 264–281. doi:10.1666/0094-8373(2008)034[0264:MGRFSD]2.0.CO;2.
- Griebeler, EM; Klein, N; Sander, PM (2013). "Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions". PLoS ONE 8 (6): e67012. doi:10.1371/journal.pone.0067012.
- Zimmer, C. (1 November 1997). DISCOVER Magazine "Dinosaurs in Motion". Discover. Retrieved 27 July 2008.
- Lovelace, D.M. (2014). "Developmental Failure of Segmentation in a Caudal Vertebra of Apatosaurus (Sauropoda)". The Anatomical Record 297 (7): 1262–1269. doi:10.1002/ar.22887.
- Trujillo, K.C.; Chamberlain, K.R.; Strickland, A. (2006). "Oxfordian U/Pb ages from SHRIMP analysis for the Upper Jurassic Morrison Formation of southeastern Wyoming with implications for biostratigraphic correlations". Geological Society of America Abstracts with Programs 38 (6): 7.
- Bilbey, S.A. (1998). "Cleveland-Lloyd Dinosaur Quarry - age, stratigraphy and depositional environments". In Carpenter, K.; Chure, D.; and Kirkland, J.I. (eds.). The Morrison Formation: An Interdisciplinary Study. Modern Geology 22. Taylor and Francis Group. pp. 87–120. ISSN 0026-7775.
- Russell, Dale A. (1989). An Odyssey in Time: Dinosaurs of North America. Minocqua, Wisconsin: NorthWord Press. pp. 64–70. ISBN 978-1-55971-038-1.
- Mateus, Octávio (2006). "Jurassic dinosaurs from the Morrison Formation (USA), the Lourinhã and Alcobaça Formations (Portugal), and the Tendaguru Beds (Tanzania): A comparison". In Foster, John R.; and Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 223–231.
- Dodson, Peter; Behrensmeyer, A.K.; Bakker, Robert T.; McIntosh, John S. (1980). "Taphonomy and paleoecology of the dinosaur beds of the Jurassic Morrison Formation". Paleobiology 6 (2): 208–232.
- Turner, C.E.; Peterson, F. (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A.". In Gillette, D.D. Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication. pp. 77–114.
- Chure, Daniel J.; Litwin, Ron; Hasiotis, Stephen T.; Evanoff, Emmett; Carpenter, Kenneth (2006). "The fauna and flora of the Morrison Formation: 2006". In Foster, John R.; and Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 233–248.
- Foster, John R. (2003). Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A. New Mexico Museum of Natural History and Science Bulletin, 23. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. p. 29.
- Carpenter, Kenneth (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus". In Foster, John R.; and Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 131–138.
- Gould, S.J. (1991). Bully for Brontosaurus: Reflections in Natural History. W. W. Norton & Co. pp. 540pp.
- Donald Crafton (1982). Before Mickey: The Animated Film 1898-1928. MIT Press. ISBN 0-262-03083-7.
- "Dinos Parade across the Silver Screen". San Diego Natural History Museum. Archived from the original on 11 October 2011.
- Glut, Donald F.; Brett-Surman, Michael K. (1997). "Dinosaurs and the media". In Farlow, James; Brett-Surman, Michael K. The Complete Dinosaur. Bloomington and Indianapolis: Indiana University Press. pp. 675–706. ISBN 978-0-253-33349-0.
- "Evolution of the Company Symbol". Sinclair Oil Corporation. 2008. Retrieved 27 August 2010.
- "Topics of The Times: Leapin' Lizards!". The New York Times. 1989-10-11. Retrieved 2008-06-08.
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