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130-507: The original 1987 release of The Puppetoon Movie contained 11 Puppetoons. The 2000 DVD release included 9 additional Puppetoons and the 2013 Blu-ray release added 7 more. In 2020, The Puppetoon Movie Volume 2 was released on Blu-ray and DVD, featuring 17 shorts not included on any of the Puppetoon Movie releases and The Ship of the Ether . On a film set, Gumby and his friends are shooting

260-403: A T. rex toe exposed above ground, making him the youngest person to discover a Tyrannosaurus . The specimen, dubbed Bucky in honor of its discoverer, was a young adult, 3.0 metres (10 ft) tall and 11 metres (35 ft) long. Bucky is the first Tyrannosaurus to be found that preserved a furcula (wishbone). Bucky is permanently displayed at The Children's Museum of Indianapolis . In

390-642: A scavenger . The question of whether Tyrannosaurus was an apex predator or a pure scavenger was among the longest debates in paleontology . Most paleontologists today accept that Tyrannosaurus was both an active predator and a scavenger. Specimens of Tyrannosaurus rex include some that are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including its life history and biomechanics . The feeding habits, physiology , and potential speed of Tyrannosaurus rex are

520-439: A bipedal gait in order to reach food or explore their environment, though there are a few cases where they walk on their hind limbs only. Several arboreal primate species, such as gibbons and indriids , exclusively walk on two legs during the brief periods they spend on the ground. Many animals rear up on their hind legs while fighting or copulating. Some animals commonly stand on their hind legs to reach food, keep watch, threaten

650-455: A broad postorbital and hourglass shaped nasals. Some of the more derived pantyrannosaurs lack nasal pneumaticity and have a lower humerus to femur ratio with their arms starting to see some reduction. Some pantyrannosaurs started developing an arctometatarsus. Eutyrannosaurs have a rough texture on their nasal bones and their mandibular fenestra is reduced externally. Tyrannosaurids lack kinetic skulls or special crests on their nasal bones, and have

780-726: A clade with fellow Asian tyrannosaurid Zhuchengtyrannus , with Lythronax being their sister taxon. A further study from 2016 by Steve Brusatte, Thomas Carr and colleagues, also indicates that Tyrannosaurus may have been an immigrant from Asia, as well as a possible descendant of Tarbosaurus . Below is the cladogram of Tyrannosauridae based on the phylogenetic analysis conducted by Loewen and colleagues in 2013. Gorgosaurus libratus [REDACTED] Dinosaur Park tyrannosaurid Daspletosaurus torosus [REDACTED] Two Medicine tyrannosaurid Bistahieversor sealeyi Lythronax argestes [REDACTED] Tyrannosaurus rex [REDACTED] Biped Bipedalism

910-490: A cluster of other human traits unique among primates, including voluntary control of breathing, hairlessness and subcutaneous fat. The " aquatic ape hypothesis ", as originally formulated, has not been accepted or considered a serious theory within the anthropological scholarly community. Others, however, have sought to promote wading as a factor in the origin of human bipedalism without referring to further ("aquatic ape" related) factors. Since 2000 Carsten Niemitz has published

1040-494: A competitor or predator, or pose in courtship, but do not move bipedally. The word is derived from the Latin words bi(s) 'two' and ped- 'foot', as contrasted with quadruped 'four feet'. Limited and exclusive bipedalism can offer a species several advantages. Bipedalism raises the head; this allows a greater field of vision with improved detection of distant dangers or resources, access to deeper water for wading animals and allows

1170-458: A convergent evolution of bipedalism evolving in arboreal environments. Hominine fossils found in dry grassland environments led anthropologists to believe hominines lived, slept, walked upright, and died only in those environments because no hominine fossils were found in forested areas. However, fossilization is a rare occurrence—the conditions must be just right in order for an organism that dies to become fossilized for somebody to find later, which

1300-410: A convex front of the vertebral body and a concave rear. The vertebral bodies had single pleurocoels, pneumatic depressions created by air sacs , on their sides. The vertebral bodies of the torso were robust but with a narrow waist. Their undersides were keeled. The front sides were concave with a deep vertical trough. They had large pleurocoels. Their neural spines had very rough front and rear sides for

1430-496: A dinosaur movie. However, the Tyrannosaurus rex , Arnie, is reluctant to act ferocious. Upon questioning, Arnie feels unfit for the part, and explains that he once was ferocious, but thanks to the influence of George Pal, he has reformed. Gumby fails to understand the profound effect of Pal, so Arnie and Pokey show Gumby a set of Pal shorts to show him the significance of the artist. Pal short films featured: Afterwards, Gumby and

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1560-477: A few subjects of debate. Its taxonomy is also controversial, as some scientists consider Tarbosaurus bataar from Asia to be a third Tyrannosaurus species, while others maintain Tarbosaurus is a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus . At present, two species of Tyrannosaurus are considered valid; the type species, T. rex , and

1690-643: A flexible backbone – both the ostrich and the red kangaroo can reach speeds of 70 km/h (43 mph), while the cheetah can exceed 100 km/h (62 mph). Even though bipedalism is slower at first, over long distances, it has allowed humans to outrun most other animals according to the endurance running hypothesis . Bipedality in kangaroo rats has been hypothesized to improve locomotor performance, which could aid in escaping from predators. Zoologists often label behaviors, including bipedalism, as "facultative" (i.e. optional) or "obligate" (the animal has no reasonable alternative). Even this distinction

1820-467: A handful of living groups. Humans, gibbons and large birds walk by raising one foot at a time. On the other hand, most macropods, smaller birds, lemurs and bipedal rodents move by hopping on both legs simultaneously. Tree kangaroos are able to walk or hop, most commonly alternating feet when moving arboreally and hopping on both feet simultaneously when on the ground. Many species of lizards become bipedal during high-speed, sprint locomotion, including

1950-468: A higher heat loss, which makes the organism more comfortable. Also, Wheeler explains that a vertical posture minimizes the direct exposure to the sun whereas quadrupedalism exposes more of the body to direct exposure. Analysis and interpretations of Ardipithecus reveal that this hypothesis needs modification to consider that the forest and woodland environmental preadaptation of early-stage hominid bipedalism preceded further refinement of bipedalism by

2080-457: A lacrimal with a distinctive process on it. Tyrannosaurids also have an interfenestral strut that is less than half as big as the maxillary fenestra. It is quite likely that tyrannosauroids rose to prominence after the decline in allosauroid and megalosauroid diversity seen during the early stages of the Late Cretaceous. Below is a simple cladogram of general tyrannosauroid relationships that

2210-908: A mass estimation technique that extrapolates from the circumference of the femur, Scotty was estimated as the largest known specimen at 8.87 t (8.73 long tons; 9.78 short tons) in body mass. Not every adult Tyrannosaurus specimen recovered is as big. Historically average adult mass estimates have varied widely over the years, from as low as 4.5 t (4.4 long tons; 5.0 short tons), to more than 7.2 t (7.1 long tons; 7.9 short tons), with most modern estimates ranging between 5.4 and 8.0 t (5.3 and 7.9 long tons; 6.0 and 8.8 short tons). A 2024 study estimated based on allometry that world-record sized T. rex specimens (1 in 100,000 individuals) may have reached lengths and weights exceeding 15 m (49 ft) and 15,000 kg (33,000 lb) respectively, though no individuals close to this size have ever been found. The study also found that there

2340-415: A more elevated eye-position, and to reduce the amount of skin exposed to the tropical sun. It is possible that bipedalism provided a variety of benefits to the hominin species, and scientists have suggested multiple reasons for evolution of human bipedalism. There is also not only the question of why the earliest hominins were partially bipedal but also why hominins became more bipedal over time. For example,

2470-456: A narrow snout, allowing unusually good binocular vision . The skull bones were massive and the nasals and some other bones were fused, preventing movement between them; but many were pneumatized (contained a "honeycomb" of tiny air spaces) and thus lighter. These and other skull-strengthening features are part of the tyrannosaurid trend towards an increasingly powerful bite, which easily surpassed that of all non-tyrannosaurids. The tip of

2600-633: A number of other dinosaur lineages such as the iguanodonts . Some extinct members of Pseudosuchia , a sister group to the avemetatarsalians (the group including dinosaurs and relatives), also evolved bipedal forms – a poposauroid from the Triassic , Effigia okeeffeae , is thought to have been bipedal. Pterosaurs were previously thought to have been bipedal, but recent trackways have all shown quadrupedal locomotion. A number of groups of extant mammals have independently evolved bipedalism as their main form of locomotion - for example humans, ground pangolins ,

2730-491: A professor at Indiana University . This hypothesis asserts that chimpanzees were only bipedal when they eat. While on the ground, they would reach up for fruit hanging from small trees and while in trees, bipedalism was used to reach up to grab for an overhead branch. These bipedal movements may have evolved into regular habits because they were so convenient in obtaining food. Also, Hunt's hypotheses states that these movements coevolved with chimpanzee arm-hanging, as this movement

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2860-612: A reconstructed skull displayed at the Museum of the Rockies . The 1990s saw numerous discoveries, with nearly twice as many finds as in all previous years, including two of the most complete skeletons found to date: Sue and Stan . Sue Hendrickson , an amateur paleontologist, discovered the most complete (approximately 85%) and largest Tyrannosaurus skeleton in the Hell Creek Formation on August 12, 1990. The specimen Sue, named after

2990-562: A reduction in inter-male antagonistic behavior in early hominids. In addition, this model is supported by a number of modern human traits associated with concealed ovulation (permanently enlarged breasts, lack of sexual swelling ) and low sperm competition (moderate sized testes, low sperm mid-piece volume) that argues against recent adaptation to a polygynous reproductive system. However, this model has been debated, as others have argued that early bipedal hominids were instead polygynous. Among most monogamous primates, males and females are about

3120-492: A savanna as it would allow the ability to look over tall grasses in order to watch out for predators, or terrestrially hunt and sneak up on prey. It was also suggested in P. E. Wheeler's "The evolution of bipedality and loss of functional body hair in hominids", that a possible advantage of bipedalism in the savanna was reducing the amount of surface area of the body exposed to the sun, helping regulate body temperature. In fact, Elizabeth Vrba 's turnover pulse hypothesis supports

3250-867: A series of papers and a book on a variant of the wading hypothesis, which he calls the "amphibian generalist theory" ( German : Amphibische Generalistentheorie ). Other theories have been proposed that suggest wading and the exploitation of aquatic food sources (providing essential nutrients for human brain evolution or critical fallback foods ) may have exerted evolutionary pressures on human ancestors promoting adaptations which later assisted full-time bipedalism. It has also been thought that consistent water-based food sources had developed early hominid dependency and facilitated dispersal along seas and rivers. Prehistoric fossil records show that early hominins first developed bipedalism before being followed by an increase in brain size. The consequences of these two changes in particular resulted in painful and difficult labor due to

3380-544: A support beam while laughing hysterically. In addition to the film shorts listed above, the following Pal film shorts are also included in the 2000 DVD edition from Image Entertainment and the 2013 Blu-ray edition from B2MP: What Ho She Bumps , Mr. Strauss Takes a Walk , Olio for Jasper , Jasper's Derby , Ether Symphony , Aladdin and the Magic Lamp , The Magic Atlas , Jasper and the Haunted House , and The Ship of

3510-638: A terrestrial feeding posture than as a walking posture. A related study conducted by University of Birmingham , Professor Susannah Thorpe examined the most arboreal great ape, the orangutan , holding onto supporting branches in order to navigate branches that were too flexible or unstable otherwise. In more than 75 percent of observations, the orangutans used their forelimbs to stabilize themselves while navigating thinner branches. Increased fragmentation of forests where A. afarensis as well as other ancestors of modern humans and other apes resided could have contributed to this increase of bipedalism in order to navigate

3640-403: A variety of ideas which promote a specific change in behaviour as the key driver for the evolution of hominid bipedalism. For example, Wescott (1967) and later Jablonski & Chaplin (1993) suggest that bipedal threat displays could have been the transitional behaviour which led to some groups of apes beginning to adopt bipedal postures more often. Others (e.g. Dart 1925) have offered the idea that

3770-478: Is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) limbs or legs . An animal or machine that usually moves in a bipedal manner is known as a biped / ˈ b aɪ p ɛ d / , meaning 'two feet' (from Latin bis 'double' and pes 'foot'). Types of bipedal movement include walking or running (a bipedal gait ) and hopping . Several groups of modern species are habitual bipeds whose normal method of locomotion

3900-586: Is also a rare occurrence. The fact that no hominine fossils were found in forests does not ultimately lead to the conclusion that no hominines ever died there. The convenience of the savanna-based theory caused this point to be overlooked for over a hundred years. Some of the fossils found actually showed that there was still an adaptation to arboreal life. For example, Lucy , the famous Australopithecus afarensis , found in Hadar in Ethiopia, which may have been forested at

4030-559: Is also proposed that one cause of Neanderthal extinction was a less efficient running. Joseph Jordania from the University of Melbourne recently (2011) suggested that bipedalism was one of the central elements of the general defense strategy of early hominids, based on aposematism , or warning display and intimidation of potential predators and competitors with exaggerated visual and audio signals. According to this model, hominids were trying to stay as visible and as loud as possible all

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4160-594: Is attributed to injuries on the bear's front paws. A two-legged fox was filmed in a Derbyshire garden in 2023, most likely having been born that way. Most bipedal animals move with their backs close to horizontal, using a long tail to balance the weight of their bodies. The primate version of bipedalism is unusual because the back is close to upright (completely upright in humans), and the tail may be absent entirely. Many primates can stand upright on their hind legs without any support. Chimpanzees , bonobos , gorillas , gibbons and baboons exhibit forms of bipedalism. On

4290-479: Is characterized by an "inverted pendulum" movement in which the center of gravity vaults over a stiff leg with each step. Force plates can be used to quantify the whole-body kinetic & potential energy, with walking displaying an out-of-phase relationship indicating exchange between the two. This model applies to all walking organisms regardless of the number of legs, and thus bipedal locomotion does not differ in terms of whole-body kinetics. In humans, walking

4420-479: Is composed of several separate processes: Early hominins underwent post-cranial changes in order to better adapt to bipedality, especially running. One of these changes is having longer hindlimbs proportional to the forelimbs and their effects. As previously mentioned, longer hindlimbs assist in thermoregulation by reducing the total surface area exposed to direct sunlight while simultaneously allowing for more space for cooling winds. Additionally, having longer limbs

4550-399: Is difficult to make a judgment about their potential usage.) The observation that large primates, including especially the great apes, that predominantly move quadrupedally on dry land, tend to switch to bipedal locomotion in waist deep water, has led to the idea that the origin of human bipedalism may have been influenced by waterside environments. This idea, labelled "the wading hypothesis",

4680-656: Is due to the fact that the narrowing of the hips and the change in the pelvic angle caused a discrepancy in the ratio of the size of the head to the birth canal . The result of this is that there is greater difficulty in birthing for hominins in general, let alone to be doing it by oneself. Bipedal movement occurs in a number of ways and requires many mechanical and neurological adaptations. Some of these are described below. Energy-efficient means of standing bipedally involve constant adjustment of balance, and of course these must avoid overcorrection . The difficulties associated with simple standing in upright humans are highlighted by

4810-438: Is important to distinguish between adaptations for bipedalism and adaptations for running, which came later still. The form and function of modern-day humans' upper bodies appear to have evolved from living in a more forested setting. Living in this kind of environment would have made it so that being able to travel arboreally would have been advantageous at the time. Although different to human walking, bipedal locomotion in trees

4940-412: Is more energy-efficient, since longer limbs mean that overall muscle strain is lessened. Better energy efficiency, in turn, means higher endurance , particularly when running long distances. Running is characterized by a spring-mass movement. Kinetic and potential energy are in phase, and the energy is stored & released from a spring-like limb during foot contact, achieved by the plantar arch and

5070-642: Is more likely a juvenile Tyrannosaurus , and the most complete juvenile example known; Jane is exhibited at the Burpee Museum of Natural History. In 2002, a skeleton nicknamed "Wyrex", discovered by amateur collectors Dan Wells and Don Wyrick, had 114 bones and was 38% complete. The dig was concluded over 3 weeks in 2004 by the Black Hills Institute with the first live online Tyrannosaurus excavation providing daily reports, photos, and video. In 2006, Montana State University revealed that it possessed

5200-542: Is not completely clear-cut — for example, humans other than infants normally walk and run in biped fashion, but almost all can crawl on hands and knees when necessary. There are even reports of humans who normally walk on all fours with their feet but not their knees on the ground, but these cases are a result of conditions such as Uner Tan syndrome — very rare genetic neurological disorders rather than normal behavior. Even if one ignores exceptions caused by some kind of injury or illness, there are many unclear cases, including

5330-401: Is now western North America , on what was then an island continent known as Laramidia . Tyrannosaurus had a much wider range than other tyrannosaurids . Fossils are found in a variety of rock formations dating to the latest Campanian - Maastrichtian ages of the late Cretaceous period , 72.7 to 66  million years ago . It was the last known member of the tyrannosaurids and among

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5460-407: Is still among the largest known land predators, with its estimated bite force being the largest among all terrestrial animals. By far the largest carnivore in its environment, Tyrannosaurus rex was most likely an apex predator , preying upon hadrosaurs , juvenile armored herbivores like ceratopsians and ankylosaurs , and possibly sauropods . Some experts have suggested the dinosaur was primarily

5590-436: Is that it evolved as a result of differentially successful survival from carrying food to share with group members, although there are alternative hypotheses. Injured chimpanzees and bonobos have been capable of sustained bipedalism. Three captive primates, one macaque Natasha and two chimps, Oliver and Poko (chimpanzee), were found to move bipedally. Natasha switched to exclusive bipedalism after an illness, while Poko

5720-429: Is the behavioral model presented by C. Owen Lovejoy , known as "male provisioning". Lovejoy theorizes that the evolution of bipedalism was linked to monogamy. In the face of long inter-birth intervals and low reproductive rates typical of the apes, early hominids engaged in pair-bonding that enabled greater parental effort directed towards rearing offspring. Lovejoy proposes that male provisioning of food would improve

5850-400: Is two-legged. In the Triassic period some groups of archosaurs (a group that includes crocodiles and dinosaurs ) developed bipedalism; among the dinosaurs , all the early forms and many later groups were habitual or exclusive bipeds; the birds are members of a clade of exclusively bipedal dinosaurs, the theropods . Within mammals , habitual bipedalism has evolved multiple times, with

5980-452: Is unknown and could well have varied between individuals but probably numbered at least forty. Sue was mounted with forty-seven of such caudal vertebrae. The neck of T. rex formed a natural S-shaped curve like that of other theropods. Compared to these, it was exceptionally short, deep and muscular to support the massive head. The second vertebra, the axis, was especially short. The remaining neck vertebrae were weakly opisthocoelous, i.e. with

6110-475: The Achilles tendon in the foot and leg, respectively. Again, the whole-body kinetics are similar to animals with more limbs. Bipedalism requires strong leg muscles, particularly in the thighs. Contrast in domesticated poultry the well muscled legs, against the small and bony wings. Likewise in humans, the quadriceps and hamstring muscles of the thigh are both so crucial to bipedal activities that each alone

6240-590: The Hell Creek Formation in Montana in 1902, comprising approximately 34 fossilized bones. Writing at the time Brown said "Quarry No. 1 contains the femur, pubes, humerus, three vertebrae and two undetermined bones of a large Carnivorous Dinosaur not described by Marsh . ... I have never seen anything like it from the Cretaceous ." Henry Fairfield Osborn , president of the American Museum of Natural History , named

6370-572: The Hell Creek Formation of Montana. This second track measures 72 centimeters (28 in) long, shorter than the track described by Lockley and Hunt. Whether or not the track was made by Tyrannosaurus is unclear, though Tyrannosaurus is the only large theropod known to have existed in the Hell Creek Formation. A set of footprints in Glenrock, Wyoming dating to the Maastrichtian stage of

6500-434: The coracoid , which was rounded. Both shoulder blades were connected by a small furcula . The paired breast bones possibly were made of cartilage only. The forelimb or arm was very short. The upper arm bone, the humerus, was short but robust. It had a narrow upper end with an exceptionally rounded head. The lower arm bones, the ulna and radius, were straight elements, much shorter than the humerus. The second metacarpal

6630-532: The foramen magnum , where the spinal cord leaves the cranium. Recent evidence regarding modern human sexual dimorphism (physical differences between male and female) in the lumbar spine has been seen in pre-modern primates such as Australopithecus africanus . This dimorphism has been seen as an evolutionary adaptation of females to bear lumbar load better during pregnancy , an adaptation that non-bipedal primates would not need to make. Adapting bipedalism would have required less shoulder stability, which allowed

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6760-430: The macropods (kangaroos, wallabies and their relatives), kangaroo rats and mice , hopping mice and springhare move bipedally by hopping. Very few non-primate mammals commonly move bipedally with an alternating leg gait. Exceptions are the ground pangolin and in some circumstances the tree kangaroo . One black bear, Pedals , became famous locally and on the internet for having a frequent bipedal gait, although this

6890-429: The macropods , kangaroo rats and mice , springhare , hopping mice , pangolins and hominin apes ( australopithecines , including humans ) as well as various other extinct groups evolving the trait independently. A larger number of modern species intermittently or briefly use a bipedal gait. Several lizard species move bipedally when running, usually to escape from threats. Many primate and bear species will adopt

7020-540: The Blu-ray also includes The Great Rupert which was produced by George Pal and the documentary The Fantasy Film Worlds of George Pal . A DVD edition from B2MP was released in 2013. The film received mixed to positive reviews. George Pal's Puppetoon body of work was recognized by a Special Oscar at the 16th Academy Awards in 1944. Pal received the Special Oscar "for the development of novel methods and techniques in

7150-564: The Ether . The 2013 Blu-ray also includes the following short films previously unavailable on home video (all of which sublicensed by Puppetoons' original distributor Paramount ): The Oscar-nominated And to Think That I Saw It on Mulberry Street , The 500 Hats of Bartholomew Cubbins , Sky Princess , Rhapsody in Wood , Date with Duke , Jasper and the Beanstalk , and Rhythm in the Ranks . In addition,

7280-457: The Late Cretaceous and hailing from the Lance Formation were described by Scott Persons, Phil Currie and colleagues in 2016, and are believed to belong to either a juvenile T. rex or the dubious tyrannosaurid Nanotyrannus lancensis . From measurements and based on the positions of the footprints, the animal was believed to be traveling at a walking speed of around 2.8 to 5 miles per hour and

7410-402: The animals to reach higher food sources with their mouths. While upright, non-locomotory limbs become free for other uses, including manipulation (in primates and rodents), flight (in birds), digging (in the giant pangolin ), combat (in bears, great apes and the large monitor lizard ) or camouflage. The maximum bipedal speed appears slower than the maximum speed of quadrupedal movement with

7540-437: The attachment of strong tendons. The sacral vertebrae were fused to each other, both in their vertebral bodies and neural spines. They were pneumatized. They were connected to the pelvis by transverse processes and sacral ribs. The tail was heavy and moderately long, in order to balance the massive head and torso and to provide space for massive locomotor muscles that attached to the thighbones. The thirteenth tail vertebra formed

7670-548: The auspices of Prof. Arthur Lakes near Golden, Colorado . In the early 1890s, John Bell Hatcher collected postcranial elements in eastern Wyoming . The fossils were believed to be from the large species Ornithomimus grandis (now Deinodon ) but are now considered T. rex remains. In 1892, Edward Drinker Cope found two vertebral fragments of a large dinosaur. Cope believed the fragments belonged to an "agathaumid" ( ceratopsid ) dinosaur, and named them Manospondylus gigas , meaning "giant porous vertebra", in reference to

7800-431: The bone. Various functions have been proposed for these foramina, such as a crocodile-like sensory system or evidence of extra-oral structures such as scales or potentially lips, with subsequent research on theropod tooth wear patterns supporting such a proposition. The vertebral column of Tyrannosaurus consisted of ten neck vertebrae, thirteen back vertebrae and five sacral vertebrae. The number of tail vertebrae

7930-465: The collections of the Natural History Museum , London. Dynamosaurus would later be honored by the 2018 description of another species of tyrannosaurid by Andrew McDonald and colleagues, Dynamoterror dynastes , whose name was chosen in reference to the 1905 name, as it had been a "childhood favorite" of McDonald's. From the 1910s through the end of the 1950s, Barnum's discoveries remained

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8060-521: The crested proceratosaurids, while later and more derived members belong to the Pantyrannosauria . Tyrannosaurs started out as small theropods; however at least some became larger by the Early Cretaceous . Tyrannosauroids are characterized by their fused nasals and dental arrangement. Pantyrannosaurs are characterized by unique features in their hips as well as an enlarged foramen in the quadrate,

8190-618: The crew meet other characters who Pal animated, such as the Pillsbury Doughboy and the Alka-Seltzer mascot Speedy as well as the titular monkey of the Curious George books and the titular amphibians of the Frog and Toad books. Gumby thanks Pal for making all this possible. The screen pans out and shows a gremlin , who looks at the audience, says "George Pal!" in a raspy voice, then ascends

8320-439: The defense of their home territory. Instead, the reduction of the male hominid canine is consistent with reduced inter-male aggression in a pair-bonded though group living primate. Recent studies of 4.4 million years old Ardipithecus ramidus suggest bipedalism. It is thus possible that bipedalism evolved very early in homininae and was reduced in chimpanzee and gorilla when they became more specialized. Other recent studies of

8450-419: The diminishing forests. Findings also could shed light on discrepancies observed in the anatomy of A. afarensis, such as the ankle joint, which allowed it to "wobble" and long, highly flexible forelimbs. If bipedalism started from upright navigation in trees, it could explain both increased flexibility in the ankle as well as long forelimbs which grab hold of branches. One theory on the origin of bipedalism

8580-510: The discoverer, was the object of a legal battle over its ownership. In 1997, the litigation was settled in favor of Maurice Williams, the original land owner. The fossil collection was purchased by the Field Museum of Natural History at auction for $ 7.6 million, making it the most expensive dinosaur skeleton until the sale of Stan for $ 31.8 million in 2020. From 1998 to 1999, Field Museum of Natural History staff spent over 25,000 hours taking

8710-493: The earlier in age and more recently discovered T. mcraeensis . As the archetypal theropod, Tyrannosaurus has been one of the best-known dinosaurs since the early 20th century and has been featured in film, advertising, postal stamps, and many other media. A tooth from what is now documented as a Tyrannosaurus rex was found in July 1874 upon South Table Mountain (Colorado) by Jarvis Hall (Colorado) student Peter T. Dotson under

8840-536: The earliest hominins partially bipedal? and 2. Why did hominins become more bipedal over time? He argued that these questions can be answered with combination of prominent theories such as Savanna-based, Postural feeding, and Provisioning. According to the Savanna-based theory, hominines came down from the tree's branches and adapted to life on the savanna by walking erect on two feet. The theory suggests that early hominids were forced to adapt to bipedal locomotion on

8970-641: The early dinosaur genus Eoraptor establishes its presence in the fossil record at this time. Paleontologists suspect Eoraptor resembles the common ancestor of all dinosaurs; if this is true, its traits suggest that the first dinosaurs were small, bipedal predators. The discovery of primitive, dinosaur-like ornithodirans such as Marasuchus and Lagerpeton in Argentinian Middle Triassic strata supports this view; analysis of recovered fossils suggests that these animals were indeed small, bipedal predators. Bipedal movement also re-evolved in

9100-427: The entire shaft of the element. The rear ischium was slender and straight, pointing obliquely to behind and below. In contrast to the arms, the hindlimbs were among the longest in proportion to body size of any theropod. In the foot, the metatarsus was "arctometatarsalian", meaning that the part of the third metatarsal near the ankle was pinched. The third metatarsal was also exceptionally sinuous. Compensating for

9230-595: The extinct giant ground sloth and chalicotheres . The spotted skunk will walk on its front legs when threatened, rearing up on its front legs while facing the attacker so that its anal glands , capable of spraying an offensive oil, face its attacker. Bipedalism is unknown among the amphibians . Among the non- archosaur reptiles bipedalism is rare, but it is found in the "reared-up" running of lizards such as agamids and monitor lizards . Many reptile species will also temporarily adopt bipedalism while fighting. One genus of basilisk lizard can run bipedally across

9360-527: The extinct giant ground sloths , numerous species of jumping rodents and macropods . Humans, as their bipedalism has been extensively studied, are documented in the next section. Macropods are believed to have evolved bipedal hopping only once in their evolution, at some time no later than 45 million years ago. Bipedal movement is less common among mammals , most of which are quadrupedal . All primates possess some bipedal ability, though most species primarily use quadrupedal locomotion on land. Primates aside,

9490-564: The fact that "normal" humans can crawl on hands and knees. This article therefore avoids the terms "facultative" and "obligate", and focuses on the range of styles of locomotion normally used by various groups of animals. Normal humans may be considered "obligate" bipeds because the alternatives are very uncomfortable and usually only resorted to when walking is impossible. There are a number of states of movement commonly associated with bipedalism. The great majority of living terrestrial vertebrates are quadrupeds, with bipedalism exhibited by only

9620-889: The foot structure of Ardipithecus ramidus suggest that the species was closely related to African-ape ancestors. This possibly provides a species close to the true connection between fully bipedal hominins and quadruped apes. According to Richard Dawkins in his book " The Ancestor's Tale ", chimps and bonobos are descended from Australopithecus gracile type species while gorillas are descended from Paranthropus . These apes may have once been bipedal, but then lost this ability when they were forced back into an arboreal habitat, presumably by those australopithecines from whom eventually evolved hominins. Early hominines such as Ardipithecus ramidus may have possessed an arboreal type of bipedalism that later independently evolved towards knuckle-walking in chimpanzees and gorillas and towards efficient walking and running in modern humans (see figure). It

9750-476: The greatly increased risk of falling present in the elderly, even with minimal reductions in control system effectiveness. Shoulder stability would decrease with the evolution of bipedalism. Shoulder mobility would increase because the need for a stable shoulder is only present in arboreal habitats. Shoulder mobility would support suspensory locomotion behaviors which are present in human bipedalism. The forelimbs are freed from weight-bearing requirements, which makes

9880-420: The ground sifakas move like all indrids with bipedal sideways hopping movements of the hind legs, holding their forelimbs up for balance. Geladas , although usually quadrupedal, will sometimes move between adjacent feeding patches with a squatting, shuffling bipedal form of locomotion. However, they can only do so for brief amounts, as their bodies are not adapted for constant bipedal locomotion. Humans are

10010-573: The group that includes both dinosaurs and crocodilians . All dinosaurs are thought to be descended from a fully bipedal ancestor, perhaps similar to Eoraptor . Dinosaurs diverged from their archosaur ancestors approximately 230 million years ago during the Middle to Late Triassic period, roughly 20 million years after the Permian-Triassic extinction event wiped out an estimated 95 percent of all life on Earth. Radiometric dating of fossils from

10140-419: The immense bulk of the animal, many bones throughout the skeleton were hollowed, reducing its weight without significant loss of strength. Tyrannosaurus is the type genus of the superfamily Tyrannosauroidea , the family Tyrannosauridae , and the subfamily Tyrannosaurinae; in other words it is the standard by which paleontologists decide whether to include other species in the same group. Other members of

10270-450: The increased favor of a narrow pelvis for bipedalism being countered by larger heads passing through the constricted birth canal. This phenomenon is commonly known as the obstetrical dilemma . Non-human primates habitually deliver their young on their own, but the same cannot be said for modern-day humans. Isolated birth appears to be rare and actively avoided cross-culturally, even if birthing methods may differ between said cultures. This

10400-476: The large human brain or the development of stone tools. Bipedal specializations are found in Australopithecus fossils from 4.2 to 3.9 million years ago and recent studies have suggested that obligate bipedal hominid species were present as early as 7 million years ago. Nonetheless, the evolution of bipedalism was accompanied by significant evolutions in the spine including the forward movement in position of

10530-400: The largest Tyrannosaurus skull yet discovered (from a specimen named MOR 008), measuring 5 feet (152 cm) long. Subsequent comparisons indicated that the longest head was 136.5 centimetres (53.7 in) (from specimen LACM 23844) and the widest head was 90.2 centimetres (35.5 in) (from Sue). Two isolated fossilized footprints have been tentatively assigned to T. rex . The first

10660-831: The last non- avian dinosaurs to exist before the Cretaceous–Paleogene extinction event . Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, the forelimbs of Tyrannosaurus were short but unusually powerful for their size, and they had two clawed digits. The most complete specimen measures 12.3–12.4 m (40–41 ft) in length, but according to most modern estimates, Tyrannosaurus could have exceeded sizes of 13 m (43 ft) in length, 3.7–4 m (12–13 ft) in hip height, and 8.8 t (8.7 long tons; 9.7 short tons) in mass. Although some other theropods might have rivaled or exceeded Tyrannosaurus in size , it

10790-488: The lower jaw, except at the rear. The largest found so far is estimated to have been 30.5 cm (12.0 in) long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur yet found. The lower jaw was robust. Its front dentary bone bore thirteen teeth. Behind the tooth row, the lower jaw became notably taller. The upper and lower jaws of Tyrannosaurus , like those of many dinosaurs, possessed numerous foramina , or small holes in

10920-456: The need for more vigilance against predators could have provided the initial motivation. Dawkins (e.g. 2004) has argued that it could have begun as a kind of fashion that just caught on and then escalated through sexual selection. And it has even been suggested (e.g. Tanner 1981:165) that male phallic display could have been the initial incentive, as well as increased sexual signaling in upright female posture. The thermoregulatory model explaining

11050-482: The numerous openings for blood vessels he found in the bone. The M. gigas remains were, in 1907, identified by Hatcher as those of a theropod rather than a ceratopsid. Henry Fairfield Osborn recognized the similarity between Manospondylus gigas and T. rex as early as 1917, by which time the second vertebra had been lost. Owing to the fragmentary nature of the Manospondylus vertebrae, Osborn did not synonymize

11180-521: The offspring survivorship and increase the pair's reproductive rate. Thus the male would leave his mate and offspring to search for food and return carrying the food in his arms walking on his legs. This model is supported by the reduction ("feminization") of the male canine teeth in early hominids such as Sahelanthropus tchadensis and Ardipithecus ramidus , which along with low body size dimorphism in Ardipithecus and Australopithecus , suggests

11310-456: The only primates who are normally biped, due to an extra curve in the spine which stabilizes the upright position, as well as shorter arms relative to the legs than is the case for the nonhuman great apes . The evolution of human bipedalism began in primates about four million years ago, or as early as seven million years ago with Sahelanthropus or about 12 million years ago with Danuvius guggenmosi . One hypothesis for human bipedalism

11440-478: The only specimens of Tyrannosaurus , as the Great Depression and wars kept many paleontologists out of the field. Beginning in the 1960s, there was renewed interest in Tyrannosaurus , resulting in the recovery of 42 skeletons (5–80% complete by bone count) from Western North America. In 1967, Dr. William MacMannis located and recovered the skeleton named "MOR 008", which is 15% complete by bone count and has

11570-723: The open savanna after they left the trees. One of the proposed mechanisms was the knuckle-walking hypothesis, which states that human ancestors used quadrupedal locomotion on the savanna, as evidenced by morphological characteristics found in Australopithecus anamensis and Australopithecus afarensis forelimbs, and that it is less parsimonious to assume that knuckle walking developed twice in genera Pan and Gorilla instead of evolving it once as synapomorphy for Pan and Gorilla before losing it in Australopithecus. The evolution of an orthograde posture would have been very helpful on

11700-482: The origin of bipedalism is one of the simplest theories so far advanced, but it is a viable explanation. Dr. Peter Wheeler, a professor of evolutionary biology, proposes that bipedalism raises the amount of body surface area higher above the ground which results in a reduction in heat gain and helps heat dissipation. When a hominid is higher above the ground, the organism accesses more favorable wind speeds and temperatures. During heat seasons, greater wind flow results in

11830-406: The postural feeding hypothesis describes how the earliest hominins became bipedal for the benefit of reaching food in trees while the savanna-based theory describes how the late hominins that started to settle on the ground became increasingly bipedal. Napier (1963) argued that it is unlikely that a single factor drove the evolution of bipedalism. He stated " It seems unlikely that any single factor

11960-470: The pressure of natural selection . This then allowed for the more efficient exploitation of the hotter conditions ecological niche , rather than the hotter conditions being hypothetically bipedalism's initial stimulus. A feedback mechanism from the advantages of bipedality in hot and open habitats would then in turn make a forest preadaptation solidify as a permanent state. Charles Darwin wrote that "Man could not have attained his present dominant position in

12090-415: The production of short subjects known as Puppetoons". Tyrannosaurus rex Tyrannosaurus ( / t ɪ ˌ r æ n ə ˈ s ɔː r ə s , t aɪ -/ ) is a genus of large theropod dinosaur . The type species Tyrannosaurus rex ( rex meaning 'king' in Latin ), often shortened to T. rex or colloquially T-Rex , is one of the best represented theropods. It lived throughout what

12220-525: The raccoon when holding food). Bears will fight in a bipedal stance to use their forelegs as weapons. A number of mammals will adopt a bipedal stance in specific situations such as for feeding or fighting. Ground squirrels and meerkats will stand on hind legs to survey their surroundings, but will not walk bipedally. Dogs (e.g. Faith ) can stand or move on two legs if trained, or if birth defect or injury precludes quadrupedalism . The gerenuk antelope stands on its hind legs while eating from trees, as did

12350-475: The rear surface, were incisiform (their tips were chisel-like blades) and curved backwards. The D -shaped cross-section, reinforcing ridges and backwards curve reduced the risk that the teeth would snap when Tyrannosaurus bit and pulled. The remaining teeth were robust, like "lethal bananas" rather than daggers, more widely spaced and also had reinforcing ridges. Those in the upper jaw, twelve per side in mature individuals, were larger than their counterparts of

12480-582: The rock off the bones. The bones were then shipped to New Jersey where the mount was constructed, then shipped back to Chicago for the final assembly. The mounted skeleton opened to the public on May 17, 2000, in the Field Museum of Natural History. A study of this specimen's fossilized bones showed that Sue reached full size at age 19 and died at the age of 28, the longest estimated life of any tyrannosaur known. Another Tyrannosaurus , nicknamed Stan (BHI 3033), in honor of amateur paleontologist Stan Sacrison,

12610-424: The same size. That is sexual dimorphism is minimal, and other studies have suggested that Australopithecus afarensis males were nearly twice the weight of females. However, Lovejoy's model posits that the larger range a provisioning male would have to cover (to avoid competing with the female for resources she could attain herself) would select for increased male body size to limit predation risk. Furthermore, as

12740-407: The savanna-based theory by explaining the shrinking of forested areas due to global warming and cooling, which forced animals out into the open grasslands and caused the need for hominids to acquire bipedality. Others state hominines had already achieved the bipedal adaptation that was used in the savanna. The fossil evidence reveals that early bipedal hominins were still adapted to climbing trees at

12870-477: The second skeleton T. rex in 1905. The generic name is derived from the Greek words τύραννος ( tyrannos , meaning "tyrant") and σαῦρος ( sauros , meaning "lizard"). Osborn used the Latin word rex , meaning "king", for the specific name. The full binomial therefore translates to "tyrant lizard the king" or "King Tyrant Lizard", emphasizing the animal's size and presumed dominance over other species of

13000-461: The shoulder a place of evidence for the evolution of bipedalism. Unlike non-human apes that are able to practice bipedality such as Pan and Gorilla , hominins have the ability to move bipedally without the utilization of a bent-hip-bent-knee (BHBK) gait , which requires the engagement of both the hip and the knee joints. This human ability to walk is made possible by the spinal curvature humans have that non-human apes do not. Rather, walking

13130-456: The shoulder and other limbs to become more independent of each other and adapt for specific suspensory behaviors. In addition to the change in shoulder stability, changing locomotion would have increased the demand for shoulder mobility, which would have propelled the evolution of bipedalism forward. The different hypotheses are not necessarily mutually exclusive and a number of selective forces may have acted together to lead to human bipedalism. It

13260-543: The soil in the locations in which these fossils were found suggest that the area used to be much more wet and covered in thick vegetation and has only recently become the arid desert it is now. An alternative explanation is that the mixture of savanna and scattered forests increased terrestrial travel by proto-humans between clusters of trees, and bipedalism offered greater efficiency for long-distance travel between these clusters than quadrupedalism. In an experiment monitoring chimpanzee metabolic rate via oxygen consumption, it

13390-556: The species became more bipedal, specialized feet would prevent the infant from conveniently clinging to the mother - hampering the mother's freedom and thus make her and her offspring more dependent on resources collected by others. Modern monogamous primates such as gibbons tend to be also territorial, but fossil evidence indicates that Australopithecus afarensis lived in large groups. However, while both gibbons and hominids have reduced canine sexual dimorphism, female gibbons enlarge ('masculinize') their canines so they can actively share in

13520-572: The summer of 2000, crews organized by Jack Horner discovered five Tyrannosaurus skeletons near the Fort Peck Reservoir . In 2001, a 50% complete skeleton of a juvenile Tyrannosaurus was discovered in the Hell Creek Formation by a crew from the Burpee Museum of Natural History . Dubbed Jane (BMRP 2002.4.1), the find was thought to be the first known skeleton of a pygmy tyrannosaurid, Nanotyrannus , but subsequent research revealed that it

13650-541: The surface of water for some distance. Among arthropods , cockroaches are known to move bipedally at high speeds. Bipedalism is rarely found outside terrestrial animals , though at least two species of octopus walk bipedally on the sea floor using two of their arms, allowing the remaining arms to be used to camouflage the octopus as a mat of algae or a floating coconut. There are at least twelve distinct hypotheses as to how and why bipedalism evolved in humans, and also some debate as to when. Bipedalism evolved well before

13780-410: The time of Lucy's death, had curved fingers that would still give her the ability to grasp tree branches, but she walked bipedally. " Little Foot ", a nearly-complete specimen of Australopithecus africanus , has a divergent big toe as well as the ankle strength to walk upright. "Little Foot" could grasp things using his feet like an ape, perhaps tree branches, and he was bipedal. Ancient pollen found in

13910-423: The time they were also walking upright. It is possible that bipedalism evolved in the trees, and was later applied to the savanna as a vestigial trait. Humans and orangutans are both unique to a bipedal reactive adaptation when climbing on thin branches, in which they have increased hip and knee extension in relation to the diameter of the branch, which can increase an arboreal feeding range and can be attributed to

14040-514: The time. Osborn named the other specimen Dynamosaurus imperiosus in a paper in 1905. In 1906, Osborn recognized that the two skeletons were from the same species and selected Tyrannosaurus as the preferred name. In 1941, the T. rex type specimen was sold to the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, for $ 7,000. The original Dynamosaurus material now resides in

14170-540: The time. Several morphological and behavioral developments were employed to achieve this goal: upright bipedal posture, longer legs, long tightly coiled hair on the top of the head, body painting , threatening synchronous body movements, loud voice and extremely loud rhythmic singing/stomping/drumming on external subjects. Slow locomotion and strong body odor (both characteristic for hominids and humans) are other features often employed by aposematic species to advertise their non-profitability for potential predators. There are

14300-422: The transition point between the deep tail base and the middle tail that was stiffened by a rather long front articulation processes. The underside of the trunk was covered by eighteen or nineteen pairs of segmented belly ribs. The shoulder girdle was longer than the entire forelimb. The shoulder blade had a narrow shaft but was exceptionally expanded at its upper end. It connected via a long forward protrusion to

14430-429: The two genera, instead considering the older genus indeterminate. In June 2000, the Black Hills Institute found around 10% of a Tyrannosaurus skeleton ( BHI 6248) at a site that might have been the original M. gigas locality. Barnum Brown , assistant curator of the American Museum of Natural History , found the first partial skeleton of T. rex in eastern Wyoming in 1900. Brown found another partial skeleton in

14560-567: The tyrannosaurine subfamily include the North American Daspletosaurus and the Asian Tarbosaurus , both of which have occasionally been synonymized with Tyrannosaurus . Tyrannosaurids were once commonly thought to be descendants of earlier large theropods such as megalosaurs and carnosaurs , although more recently they were reclassified with the generally smaller coelurosaurs . The earliest tyrannosaur group were

14690-466: The upper jaw was U-shaped (most non-tyrannosauroid carnivores had V-shaped upper jaws), which increased the amount of tissue and bone a tyrannosaur could rip out with one bite, although it also increased the stresses on the front teeth. The teeth of T. rex displayed marked heterodonty (differences in shape). The premaxillary teeth, four per side at the front of the upper jaw, were closely packed, D -shaped in cross-section, had reinforcing ridges on

14820-543: The world without the use of his hands, which are so admirably adapted to the act of obedience of his will". Darwin (1871:52) and many models on bipedal origins are based on this line of thought. Gordon Hewes (1961) suggested that the carrying of meat "over considerable distances" (Hewes 1961:689) was the key factor. Isaac (1978) and Sinclair et al. (1986) offered modifications of this idea, as indeed did Lovejoy (1981) with his "provisioning model" described above. Others, such as Nancy Tanner (1981), have suggested that infant carrying

14950-523: The world's fastest lizard, the spiny-tailed iguana (genus Ctenosaura ). The first known biped is the bolosaurid Eudibamus whose fossils date from 290 million years ago. Its long hind-legs, short forelegs, and distinctive joints all suggest bipedalism. The species became extinct in the early Permian . All birds are bipeds, as is the case for all theropod dinosaurs . However, hoatzin chicks have claws on their wings which they use for climbing. Bipedalism evolved more than once in archosaurs ,

15080-470: Was 3.66–3.96 m (12.0–13.0 ft) tall at the hips, and according to the most recent studies, using a variety of techniques, maximum body masses have been estimated approximately 8.4–8.46 t (8.27–8.33 long tons; 9.26–9.33 short tons). A specimen nicknamed Scotty (RSM P2523.8), located at the Royal Saskatchewan Museum , is reported to measure 13 m (43 ft) in length. Using

15210-553: Was discovered at Philmont Scout Ranch , New Mexico, in 1983 by American geologist Charles Pillmore. Originally thought to belong to a hadrosaurid , examination of the footprint revealed a large 'heel' unknown in ornithopod dinosaur tracks, and traces of what may have been a hallux , the dewclaw-like fourth digit of the tyrannosaur foot. The footprint was published as the ichnogenus Tyrannosauripus pillmorei in 1994, by Martin Lockley and Adrian Hunt. Lockley and Hunt suggested that it

15340-529: Was discovered in captivity in a tall, narrow cage. Oliver reverted to knuckle-walking after developing arthritis. Non-human primates often use bipedal locomotion when carrying food, or while moving through shallow water. Other mammals engage in limited, non-locomotory, bipedalism. A number of other animals, such as rats , raccoons , and beavers will squat on their hindlegs to manipulate some objects but revert to four limbs when moving (the beaver will move bipedally if transporting wood for their dams , as will

15470-475: Was estimated to have a hip height of 1.56 to 2.06 m (5.1 to 6.8 ft). A follow-up paper appeared in 2017, increasing the speed estimations by 50–80%. T. rex was one of the largest land carnivores of all time. One of its largest and the most complete specimens, nicknamed Sue (FMNH PR2081), is located at the Field Museum of Natural History in Chicago. Sue measured 12.3–12.4 m (40–41 ft) long,

15600-504: Was found after an analysis conducted by Li and colleagues in 2009. Guanlong [REDACTED] Proceratosaurus Dilong [REDACTED] Eotyrannus Xiongguanlong [REDACTED] Appalachiosaurus Tyrannosauridae [REDACTED] Many phylogenetic analyses have found Tarbosaurus bataar to be the sister taxon of T. rex . The discovery of the tyrannosaurid Lythronax further indicates that Tarbosaurus and Tyrannosaurus are closely related, forming

15730-450: Was found that the quadrupedal and bipedal energy costs were very similar, implying that this transition in early ape-like ancestors would not have been very difficult or energetically costing. This increased travel efficiency is likely to have been selected for as it assisted foraging across widely dispersed resources. The postural feeding hypothesis has been recently supported by Dr. Kevin Hunt,

15860-399: Was key, while others again have suggested stone tools and weapons drove the change. This stone-tools theory is very unlikely, as though ancient humans were known to hunt, the discovery of tools was not discovered for thousands of years after the origin of bipedalism, chronologically precluding it from being a driving force of evolution. (Wooden tools and spears fossilize poorly and therefore it

15990-408: Was little evidence of size-based sexual dimorphism in T. rex . The largest known T. rex skulls measure up to 1.54 m (5.1 ft) in length. Large fenestrae (openings) in the skull reduced weight, as in all carnivorous theropods. In other respects Tyrannosaurus 's skull was significantly different from those of large non- tyrannosaurid theropods. It was extremely wide at the rear but had

16120-463: Was longer and wider than the first, whereas normally in theropods the opposite is true. The forelimbs had only two clawed fingers, along with an additional splint-like small third metacarpal representing the remnant of a third digit. The pelvis was a large structure. Its upper bone, the ilium , was both very long and high, providing an extensive attachment area for hindlimb muscles. The front pubic bone ended in an enormous pubic boot, longer than

16250-459: Was originally suggested by the Oxford marine biologist Alister Hardy who said: "It seems to me likely that Man learnt to stand erect first in water and then, as his balance improved, he found he became better equipped for standing up on the shore when he came out, and indeed also for running." It was then promoted by Elaine Morgan , as part of the aquatic ape hypothesis , who cited bipedalism among

16380-409: Was recovered from the Hell Creek Formation in 1992. Stan is the second most complete skeleton found, with 199 bones recovered representing 70% of the total. This tyrannosaur also had many bone pathologies, including broken and healed ribs, a broken (and healed) neck, and a substantial hole in the back of its head, about the size of a Tyrannosaurus tooth. In 1998, 20-year-old Bucky Derflinger noticed

16510-715: Was responsible for such a dramatic change in behaviour. In addition to the advantages of accruing from ability to carry objects – food or otherwise – the improvement of the visual range and the freeing of the hands for purposes of defence and offence may equally have played their part as catalysts." Sigmon (1971) demonstrated that chimpanzees exhibit bipedalism in different contexts, and one single factor should be used to explain bipedalism: preadaptation for human bipedalism. Day (1986) emphasized three major pressures that drove evolution of bipedalism: food acquisition, predator avoidance, and reproductive success. Ko (2015) stated that there are two questions main regarding bipedalism 1. Why were

16640-467: Was thought to be advantageous. It has also been proposed that, like some modern-day apes, early hominins had undergone a knuckle-walking stage prior to adapting the back limbs for bipedality while retaining forearms capable of grasping . Numerous causes for the evolution of human bipedalism involve freeing the hands for carrying and using tools, sexual dimorphism in provisioning, changes in climate and environment (from jungle to savanna ) that favored

16770-454: Was very effective and efficient in harvesting food. When analyzing fossil anatomy, Australopithecus afarensis has very similar features of the hand and shoulder to the chimpanzee, which indicates hanging arms. Also, the Australopithecus hip and hind limb very clearly indicate bipedalism, but these fossils also indicate very inefficient locomotive movement when compared to humans . For this reason, Hunt argues that bipedalism evolved more as

16900-400: Was very likely the track was made by a T. rex , which would make it the first known footprint from this species. The track was made in what was once a vegetated wetland mudflat. It measures 83 centimeters (33 in) long by 71 centimeters (28 in) wide. A second footprint that may have been made by a Tyrannosaurus was first reported in 2007 by British paleontologist Phil Manning, from

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