Diplodocus
Diplodocus (Gr. "double beam"), also Spanish diplodocus, is a genus with three known species of diplodocid sauropod dinosaurs, which lived in the late Jurassic period, approximately 155.7 to 145 million years ago, in the Kimmeridgian and Tithonian, in what is now North America. The first fossils were discovered in 1877 by S. W. Williston.
It lived in what is now western North America during the Late Jurassic period. Diplodocus is one of the most common dinosaurs found in the upper part of the Morrison Formation, a sequence of marine and alluvial sediments deposited approximately 152 million years ago. The Morrison Formation shows an environment dominated by gigantic sauropods such as Camarasaurus, Barosaurus, Apatosaurus and Brachiosaurus, in addition to the Diplodocus.
The Diplodocus is among the most easily identifiable of dinosaurs, with its classic shape, long neck and tail, and four stout legs. For many years, it was the largest known dinosaur. Its large size may have been an impediment to the predatory Allosaurus and Ceratosaurus, whose remains have been found in the same strata, suggesting that they coexisted with Diplodocus .
Etymology
The generic name Diplodocus is the Neo-Latin form derived from the Greek διπλόος (diploös) “double” and δοκός (dokos) "beam", referring to the shape of the chevron bones along the underside of the tail. The term was coined by Othniel Charles Marsh in 1878, thinking that this chevrone shape of the bones was unique to Diplodocus. Later, however, it was discovered in other members of the Diplodocid family and in non-Diplodocid sauropods such as Mamenchisaurus.[citation needed]
Description
The Diplodocus are among the best-known dinosaurs. They were very large quadrupedal animals, with a long neck and an extensive whip-shaped tail. Its front limbs were slightly shorter than the hind limbs, giving it a predominantly horizontal posture. The mechanics of these long-necked and tailed animals, with four massive legs, have been compared to that of a suspension bridge. The type specimen of Diplodocus carnegii, CM 84 it is the most complete found of its genus, estimated to be around 25 meters long and 6.5 m high at the neck. For the species of D. carnegii, known from well-preserved remains. estimates of its mass are in the range of 11.5 to 19.7 tons with the following values according to the authors 11.5 tons, 12.7 tons, 16 tons, and 19.7 tons. Modern mass estimates for Diplodocus carnegii they tend to be in the 10 to 16 metric ton range. Although dinosaurs like the Supersaurus were probably larger, fossil remains found of these other species are only partial.
The partial remains of D. hallorum have increased the estimated length of the genus, although not by as much as previously thought. When it was described in 1991, the discoverer, David Gillette, calculated that it could have been up to 52 meters long, making it the longest known dinosaur, except for the dubious dinosaurs poorly known as Amphicoelias. Some weight estimates ranged as far as 113 tons. The initial estimated length was later revised downward to 33.5 meters and then to 32 meters. A more recent revision shows that the giant tail vertebrae were actually positioned further forward in the tail than D. Gillette did. had originally located. Gillette had originally placed vertebrae 12-19 as vertebrae 20-27. The study shows that the complete skeleton of Diplodocus at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, on which estimates of Diplodocus (Seismosaurus) hallorum were based, included the thirteenth tail vertebra belonging to another animal, which reduced estimates of the size of D. hallorum by about 30%, remaining at approximately 32 meters long and 25-30 tons.
Neck and head
Their neck was made up of at least 15 vertebrae, so it is believed that they held their neck parallel to the ground and were incapable of raising it significantly, no more than 30 degrees above their horizontal axis. No skull has ever been found that can be said with certainty to belong to Diplodocus, although the skulls of other diplodocids closely related to Diplodocus, such as Galeamopus, are well known. . Diplodocid skulls were very small compared to the size of these animals. Diplodocus had small "peg"shaped teeth; they pointed forward and were only present in the anterior sections of the jaws. Its braincase was small as in other diplodocids. The Diplodocus head has been widely represented with the nostrils on the upper part of the head, due to the position of the nostrils at the apex of the skull. There has been speculation as to whether such a configuration means that Diplodocus had a proboscis. But a recent study claimed that there is no paleoneuroanatomical evidence to support the proboscis hypothesis. It has been pointed out that the facial nerve of animals such as the elephant is long, since it innervates a trunk. Evidence suggests that the facial nerve is very small in Diplodocus. Studies by Lawrence Witmer published in 2001 indicated that, while the nasal openings were high on the head, the present fleshy nostrils were situated much lower on the muzzle.
Tail
The Diplodocus had an extremely long tail, composed of more than 80 caudal vertebrae, an amount that was practically double the number of some primitive sauropods, such as Shunosaurus > with 43, and which also exceeds that of contemporary Macronarians, such as Camarasaurus with 53. There is speculation that diplodocus could have used its tail for defense or to make noise like a whip. It could also have served as a counterweight for the neck. The middle part of the tail had "double beams," oddly shaped chevron bones that give Diplodocus their name. These may have served to provide support for the vertebrae, or perhaps to prevent the blood vessels from collapsing should the animal's heavy tail crash into the ground or some reckless predator. These "double beams" they also appear in some dinosaurs related to Diplodocus.
Members
Like other sauropods, the hand or "front foot" of Diplodocus was highly modified, with the finger and hand bones arranged in a vertical column, with a horseshoe-shaped cut section. Diplodocus lacked claws except for finger 1, which were unusually large compared to other sauropods, flattened from side to side, and separated from the hand bones. The function of this unusually specialized claw is unknown.
Other anatomical aspects
Recent discoveries have shown that Diplodocus and other diplodocids may have had narrow, pointed keratin spines around their backs, like those of an iguana, up to 18 centimeters high on their tail and possibly along the back and neck as well, as in hadrosaurids. This feature, radically different from the previous image of these animals, has been incorporated in recent reconstructions, such as Walking with Dinosaurs. The description The original author of the spines reported that specimens at the Howe Quarry near Shell, Wyoming were associated with skeletal remains of an undescribed diplodocid "resembling Diplodocus and Barosaurus. Since then, specimens from this quarry have been referred to as Kaatedocus siberi and Barosaurus sp., rather than Diplodocus.
Discovery and research
Several species of Diplodocus were described between 1878 and 1924. The first skeleton was found in 1878 in Como Bluff, Wyoming, by Benjamin Mudge and Samuel Wendell Williston. It was the paleontologist Othniel Charles Marsh who named it Diplodocus longus, "double long beam", that same year. Since then, remains of Diplodocus have been found in the Morrison Formation, in the western United States, in Colorado, in Utah, Montana and Wyoming. Fossils of these dinosaurs are relatively common, except for the skull, which has never been found complete.
The two genera of sauropods from the Morrison Formation, Diplodocus and Barosaurus, share very similar limb bones. In the past, many isolated bones were automatically attributed to Diplodocus but may, in fact, have belonged to Barosaurus.
Diplodocus longus, the original type species is known from two complete fragmentary caudal vertebrae and several more from the Morrison Formation at Felch Quarry in Colorado. Although several more complete specimens have been attributed to D. longus, detailed analysis has suggested that the original fossil lacks the characteristics necessary to allow comparison with other specimens. For this reason, it has been considered a nomen dubium, which is not an ideal situation for the type species of a genus known as Diplodocus. A petition to the International Commission on Zoological Nomenclature is being considered proposing to make D. carnegii the new type species.
D. lacustris is a dubious species, named by Marsh in 1884 from remains of a small animal from Morrison, Colorado. These bones are now believed to have belonged to an animal immature, rather than a separate species. In 2015, it was concluded that the specimen actually belonged to Camarasaurus
D. carnegii, also spelled D. carnegiei, named for Andrew Carnegie, is the best known, mainly due to a nearly complete skeleton, specimen CM 84 collected by Jacob Wortman, of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. and was described and named by John Bell Hatcher in 1901. This was considered as the type species for Diplodocus by Tschopp in 2016. Although it is not the holotype species, the best known is Diplodocus carnegie, the most famous being due to the large number of exhibits of its skeleton in museums around the world.
Diplodocus hayi, known from a partial skeleton and skull discovered by William H. Utterback in 1902 near Sheridan, Wyoming, was described in 1924. In 2015, it was renamed the separate genus Galeamopus and several other Diplodocus specimens were referred to that genus, leaving no known Diplodocus skulls.
Diplodocus hallorum was first described in 1991 by Gillette as Seismosaurus halli from a partial skeleton comprising vertebrae, pelvis and ribs, specimen NMMNH P- 3690, was found in 1979. As the specific name honors two people, Jim and Ruth Hall, George Olshevsky later suggested amending the name as S. hallorum, using the obligatory genitive plural, Gillette later modified the name, whose use was followed by others, including Carpenter in 2006. In 2004, a presentation at the annual conference of the Geological Society of America argued that Seismosaurus is considered a more modern synonym of Diplodocus. This was followed by a much more detailed publication in 2006, which not only renamed the species Diplodocus hallorum, but also noted that it might be the same as D. longus. The position of D. hallorum should be considered as a specimen of D. longus was also taken by the authors of a redescription of Supersaurus, disproving a previous hypothesis that Seismosaurus and Supersaurus were the same thing.. A 2015 analysis of diplodocid relationships noted that these views are based on the most complete reported specimens of D. longus. The authors of this analysis concluded that these specimens were in fact the same species as D. hallorum, but that D. longus was a nomen dubium.
Classification
Diplodocus is the type genus and gives its name to the family Diplodocidae, to which it belongs. Members of this family, although large in size, have a more slender build compared to the family Diplodocidae. from other sauropods, such as titanosaurs and brachiosaurids. All are characterized by long necks and tails and a horizontal posture, with the forelimbs shorter than the hindquarters. Diplodocids dominated North America and possibly Africa in the late Jurassic and appear to have been replaced by titanosaurids during the Cretaceous.
A subfamily, Diplodocinae, was created to include Diplodocus and their closest relatives, including Barosaurus. Apatosaurus, although contemporary, is more distantly related, but is still considered a diplodocid though not a diplodocine, as it is a member of the subfamily Apatosaurinae. The genera Dinheirosaurus and Tornieria have also been identified as close relatives of Diplodocus by some authors.
The Diplodocoidea group includes diplodocids, as well as dicreosaurids, rebachisaurids, Suuwassea, Amphicoelias, and possibly Haplocanthosaurus. Previously included the Nemegtosauridae, today included within Lithostrotia within Titanosauria. This clade is the sister group to the camarasaurids, brachiosaurids, and titanosaurs; the Macronaria. The set of these taxa make up the Neosauropoda, the largest, most diverse and most successful group of sauropodomorph dinosaurs.
Phylogeny
The following cladogram is based on phylogenetic analysis by Whitlock in 2011, showing the relationships of Diplodocus among the other genera assigned to the family Diplodocidae:
| Diplodocidae |
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Cladogram of Diplodocidae made by Tschopp, Mateus and Benson in 2015, which is made by species, note the absence of D. longus since D. carnegii is considered the type of the genus.
| Diplodocidae |
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Paleobiology
Due to the large number of skeletal remains, Diplodocus is one of the best-studied dinosaurs. Many aspects of their lifestyle have been the subject of various theories over the years. Comparisons between the scleral rings of diplodocine and modern birds and reptiles suggest that they may have been cathemeral, active throughout the day at intervals short.
Marsh and later Hatcher assumed that the animal was aquatic, due to the position of its nasal openings at the apex of the skull. Similar aquatic behavior was commonly described for other large sauropods, such as Brachiosaurus and Apatosaurus. A 1951 study by Kenneth A. Kermack indicates that sauropods probably could not have breathed through the nose when the rest of the body was submerged, as the water pressure on the chest wall would be too great. Since the 1970s, the general consensus has sauropods as firmly terrestrial animals, navigating among trees, ferns, and shrubs.
Scientists have debated how sauropods could breathe with their large bodies and long necks, which would have increased the amount of dead space. They probably had an avian respiratory system, which is more efficient than a mammalian and reptilian system. Reconstructions of the neck and thorax of Diplodocus show great pneumaticity that could have played a role in respiration as it does in birds.
Posture
Representation of the posture of Diplodocus has changed considerably over the years. For example, a classic 1910 work by Oliver P. Hay depicts two Diplodocus loitering on a river bank. These animals have members open to the sides, similar to those of lizards. Hay argued that Diplodocus had a lizard-like gait with legs sticking out on either side, a claim that was supported by Gustav Tornier. However, this hypothesis was refuted by William J. Holland, who showed that a Diplodocus with this posture would have needed a hole to pass its belly through.
Later, diplodocids were often portrayed with their necks high, allowing them to eat from tall trees, but recently, scientists argued that the heart would have had trouble maintaining the blood pressure needed to oxygenate the brain. In addition, later studies verified that the structure of the cervical vertebrae could not allow the neck to move so high. Studies analyzing the morphology of sauropod necks have concluded that the neutral posture of the Diplodocus neck was nearly horizontal, rather than vertical, and scientists such as Kent Stevens have used this to argue that sauropods, including Diplodocus, did not raise their heads too high above their shoulders. A 2009 study found that all tetrapods appear to hold the base of their necks to the maximum possible vertical extension when in a normal, alert posture and argued that the same would be true for sauropods barring unknown and unique features that they distinguish the anatomy of the soft tissues of their necks from other animals. The study found fault with Stevens' assumptions regarding the potential range of motion in sauropod necks, and based on the comparison of skeletons with living animals, the study also argued that soft tissues might have greater flexibility than is suggest bones. For these reasons, they argued that Diplodocus would have held its neck at a higher angle than previous studies had concluded.
As with Barosaurus, the long neck of Diplodocus is the source of much controversy among scientists. In 1992, a Columbia University study of diplodocid neck structure indicated that necks this long would have required a 1.6-ton heart. The study proposed that animals like this one must have had 'hearts'; rudimentary auxiliaries in their necks, whose sole purpose would have been to pump blood to the next 'heart'.
Food
Compared to the teeth of other sauropods, those of Diplodocus were very strange. Dental crowns were long, thin, and elliptical in cross section, while the apex forms a blunt, triangular point. The most prominent wear facet is at the apex; however, unlike the other wear patterns observed within sauropods, those of Diplodocus are located on the labial side, against the cheek, of the upper and lower teeth. This means that the Diplodocus and other diplodocids had a radically different feeding mechanism than other sauropods. Stripping branches using one side of the snout is the most likely form of feeding for Diplodocus, as it explains the unusual patterns of tooth wear from tooth-food contact. When stripping branches using one side of the snout, one row of teeth would have been used to pluck foliage from the stem, while the other would have acted as a guide and stabilizer. Due to the elongated preorbital region of the skull (in front of the eyes), it could strip larger portions of stems in a single action. The backward movement of the lower jaws may have contributed two significant functions in the behavior of feeding, increasing the mouth opening and allowing fine adjustments in the relative positions of the tooth rows to fine tune defoliation.
The flexibility of the Diplodocus neck is debated, but it should have been able to navigate from low levels to about 4 meters when on all fours. However, studies have shown that the center Diplodocus's mass was very close to the hip socket. This means that Diplodocus could return to a bipedal posture with relatively little effort. It also had the advantage of using its large tail as a prop that would allow for a very stable tripod stance. In a tripod stance, Diplodocus could potentially increase its feeding height to approximately 11 meters. With a laterally and dorsoventrally flexible neck and the ability to use its tail to prop itself up on its hind limbs, a "tripod" ability, Diplodocus would have had the ability to feed on leaves at many levels, under, intermediate and tall, up to approximately 10 meters above the ground, from small ginkgos to colossal monkey puzzle trees. The range of motion of the neck would also have allowed the head to rest below the level of the body, leading some scientists to speculate about whether Diplodocus grazed on submerged aquatic plants on the banks of rivers. This concept of the feeding posture is supported by the relative lengths of the forelimbs and hindlimbs. Additionally, its peg-like teeth may have been used to eat soft aquatic plants.
Matthew Cobley and colleagues in 2013 dispute the above, finding that large muscles and cartilage would give limited neck movement. They state that the foraging ranges of sauropods such as Diplodocus were smaller than previously believed and the animals may have had to move their bodies to better access areas where they can select vegetation. As such, they could have spent more time eating to meet their minimal energy needs. The conclusions of Cobley and colleagues were disputed in 2013 and 2014 by Mike Taylor, who analyzed the amount and position of intervertebral cartilage to determine neck flexibility. of Diplodocus and Apatosaurus. Taylor discovered that the neck of Diplodocus was very flexible and that Cobley and colleagues were wrong in stating that the flexibility implicit in bones is less.
Young and colleagues in 2012 used biomechanical models to examine the skull performance of diplodocinids. It was concluded that the proposal that their dentition was used for debarking was not supported by the data, which showed that under such a scenario, the skull and teeth would undergo extreme stress. The branch biting and precision biting hypotheses were shown to be biomechanically plausible feeding behaviors. The teeth were also continuously replaced throughout their lives, usually in less than 35 days, as discovered by Michael D&# 39; Emic et al. Within each tooth socket, up to five replacement teeth developed to replace the next one. Studies of the teeth also reveal that it preferred a different vegetation than Morrison's other sauropods, such as Camarasaurus. This may have better allowed the various sauropod species to exist without competition.
In 2010, Whitlock and colleagues described a juvenile skull at the time referred to as Diplodocus, CM 11255, which differed greatly from adult skulls of the same genus, its snout it was not blunt and the teeth were not confined to the front of the muzzle. These differences suggest that adults and juveniles fed differently. Such an ecological difference between adults and juveniles had not been previously observed in sauropodomorphs.
Like other sauropods, when it came to digesting the vegetables they fed on, they used gastroliths. The distribution of gastroliths found next to a fossil of D. hallorum, divided into two separate sets, could suggest that these animals had a digestive system similar to that of modern birds, with a crop and a gizzard, and that each group of gastroliths belonged to each of these cavities.
Reproduction and growth
While the long neck has traditionally been interpreted as an adaptation for feeding, it has also been suggested that the oversized neck of Diplodocus and its relatives may have been primarily a sexual display, with whatever other benefits diet in second place. A 2011 study refuted this idea in detail.
Although there is no evidence of nesting habits of Diplodocus, other sauropods, such as the titanosaur Saltasaurus, have been associated with nest sites. Nest sites of titanosaurs, indicate that it may have laid its eggs communally over a large area in many low pits, each covered with vegetation. This has generated speculation that Diplodocus may have exhibited similar behaviour. Another theory is the inclusion of females in areas with more leafy trees, once fertilized, for the deposition of eggs in a "more secure" than the forlorn plain on which they habitually subsisted. The documentary Walking with Dinosaurs portrayed a mother Diplodocus using an ovipositor to lay eggs, but this was pure speculation on the part of the documentary's author. In Diplodocus and other sauropods, the Clutch sizes and individual eggs were surprisingly small for such large animals. This appears to have been an adaptation to predation pressures, as large eggs would require a longer incubation time and therefore be at greater risk.
According to various bone histology studies, Diplodocus, like other sauropods, grew at a very rapid rate, reaching sexual maturity in just a decade and continuing to grow throughout the years. throughout their lives. This stance is radically different from that attributed to sauropods, which were thought to grow slowly over their lifetimes, taking decades to reach maturity.
Paleoecology
The Morrison Formation is a sequence of shallow marine and alluvial sediments that, according to radiometric dating, ranges from 156.3 million years old at its bottom, to 146.8 million years old at the top, making it which places it in the final stages of the Oxfordian, Kimmeridgian, and early Tithonian of the Late Jurassic Period. This formation is interpreted as a semi-arid environment with distinct wet and dry seasons. The Morrison Basin, where the dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan and was formed when the precursors of the Front Range of the Rocky Mountains began to push west. Deposits from its east-facing drainage basins were transported 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..
The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs. Known dinosaurs from the Morrison include the theropods Ceratosaurus, Koparion, Stokesosaurus i>, Ornitholestes, Allosaurus, Saurophaganax and Torvosaurus, the sauropods Apatosaurus, Brontosaurus, Brachiosaurus, Camarasaurus and Diplodocus, and the ornithischians Camptosaurus, Dryosaurus, Othnielia, Gargoyleosaurus and Stegosaurus among others. Diplodocus is commonly found in the same sites as Apatosaurus, Allosaurus, Camarasaurus, and Stegosaurus. 70 to 75% of theropod specimens and was in the upper trophic level of the Morrison food web. Many of the dinosaurs from the Morrison Formation are of the same genus as those seen in the Portuguese Formation rocks. Lourinha, mainly Allosaurus, Ceratosaurus, Torvosaurus and Stegosaurus or have a close counterpart, Brachiosaurus and Lusotitan, Camptosaurus and Draconyx. Other vertebrates that shared this paleoenvironment included ray-finned fish, frogs, salamanders, turtles such as Dorsetochelys, sphenodonts, lizards, terrestrial and aquatic crocodilemorphs such as Hoplosuchus and several species of pterosaurs such as Harpactognathus and Mesadactylus and docodont, multituberculate, symmetrodont, and triconodont primitive mammals. Bivalve shells 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 various families of conifers. Vegetation varied from forests of tree ferns and ferns, gallery forests, to fern savannahs with occasional trees, such as the Araucaria-type conifer Brachyphyllum.
In popular culture
The Diplodocus is a famous and highly represented dinosaur since it has been exhibited in more places than any other sauropod. Much of this has been due to the abundance of skeletal remains and its long being considered the longest dinosaur. At the same time, the donations made by Andrew Carnegie, at the turn of the XX century, to potentates around the world of many skeletons mounted plaster casts did a lot to make people all over the world familiar with this dinosaur. Plaster copies of Diplodocus skeletons are still on display in many museums around the world, including a rare D. hayi at the Houston Museum of Natural Science. The series of plaster prints of D. carnegiei that the patron Andrew Garnegie and his wife gave to different museums and institutions is the most famous set of skeletons made from the original specimen. Institutions such as the Natural History Museum in London, the National Museum of Natural History of France in Paris, the National Museum of Natural Sciences in Madrid, the Museum of Natural History in Berlin, the Senckenberg Museum (in Frankfurt, Germany), the Museum of Natural History in Mexico City, the Field Museum of Natural History in Chicago, the Museo de La Plata in Argentina and, of course, the original remains one of the centers of attention of the collections of the Carnegie Museum of Natural History in Pittsburgh. A mounted skeleton of D. longus is in the United States National Museum of Natural History in Washington D.C., while a mounted skeleton of D. hallorum (formerly Seismosaurus), which may be the same as D. longus, can be found at the New Mexico Museum of Natural History and Science.
Diplodocus has been a frequent subject in dinosaur movies, documentaries and fiction. It was shown in the second episode of the award-winning BBC television series; Walking with Dinosaurs. The episode "Age of the Titans" follows the life of a Diplodocus 152 million years ago, facing attacks by Ornitholestes, Stegosaurus and Allosaurus. The animated film Fantasia features many sauropods in the "Rite of Spring" segment, one of which appears to be a Diplodocus. In literature, James A. Michener's book Centennial has a chapter devoted to Diplodocus, narrating the life and death of an individual. Diplodocus is a figure that is usually seen among toy dinosaurs and among models. It has had two different toy models in the Carnegie toy collection (the Carnegie Collection, see the corresponding English Wikipedia article here). In the movie The Lost World: Jurassic Park, several sauropods appear that could perhaps be identified, some as Diplodocus and others as Mamenchisaurus.