Is the existence of the Loch Ness Monster, the Yeti, Bigfoot etc zoologically credible?

Well, there's the curious instance of the unaccountable survival down the millennia of this little beastie:


A "Living Fossil": A specimen of Latimeria chalumnae in the Natural History Museum, Vienna, Austria (length: 170 cm - weight: 60 kg). This specimen was caught on 18 October 1974, next to Salimani/Selimani (Grand Comoro, Comoro Islands) 11°48′40.7″S 43°16′3.3″E.

Wiki:

Coelacanths ( /ˈsiːləkænθ/, adaptation of Modern Latin Cœlacanthus "hollow spine", from Greek κοῖλ-ος koilos "hollow" + ἄκανθ-α akantha "spine", referring to the hollow caudal fin rays of the first fossil specimen described and named by Agassiz in 1839[1]) are members of an order of fish that includes the oldest living lineage of Sarcopterygii (lobe-finned fish + tetrapods) known to date.

Coelacanths belong to the subclass Actinistia, a group of lobed-finned fish that are related to lungfish and other extinct Devonian fish like osteolepiforms, porolepiforms, rhizodonts, and Panderichthys. Coelacanths were thought to have gone extinct in the Late Cretaceous, but were rediscovered in 1938 off the coast of South Africa. Latimeria chalumnae and the Latimeria menadoensis are the only two living coelacanth species and are found along the coastlines of the Indian Ocean. The coelacanth has been nicknamed a “living fossil”, because its fossils were found long before the actual discovery of a live specimen. The coelacanth is thought to have first evolved approximately 400 million years ago.

Eveidence for survival of the other supposed creature named in the title of this thread, though, is practically non-existent:

********************************************************************************


Purported "Sightings" of the so-called Loch Ness Monster.

Wiki:

The Loch Ness Monster (Scottish Gaelic Niseag) is a cryptid that is reputed to inhabit Loch Ness in the Scottish Highlands. The most frequent speculation is that the creature represents a line of long-surviving plesiosaurs.


Reconstruction of Nessie as a Plesiosaur outside the Museum of Nessie

It is similar to other supposed lake monsters in Scotland and elsewhere, though its description varies from one account to the next.

Popular interest and belief in the animal has varied since it was brought to the world's attention in 1933. Evidence of its existence is anecdotal, with minimal and much-disputed photographic material and sonar readings. The scientific community regards the Loch Ness Monster as a modern-day myth, and explains sightings as a mix of hoaxes and wishful thinking. Despite this, it remains one of the most famous examples of cryptozoology. The legendary monster has been affectionately referred to by the nickname Nessie (Scottish Gaelic: Niseag) since the 1950s.

the "Surgeon's Photograph" of Nessie, 1934.

Wiki:

One of the most iconic images of Nessie is known as the "Surgeon's Photograph". Its importance lies in the fact that it was the first photo and only photographic evidence of a “head and neck” – all the others are humps or disturbances. Dr. Wilson claimed he was looking at the loch when he saw the monster, so grabbed his camera and snapped five photos. After the film was developed, only two exposures were clear. The first photo (the more publicised one) shows what was claimed to be a small head and back. The second one, a blurry image, attracted little publicity because it was difficult to interpret what was depicted. The image was revealed as a hoax in 1994.

WIKI:

Explanations

A variety of explanations have been postulated over the years to account for sightings of the Loch Ness Monster. These may be categorised as: misidentifications of common animals; misidentifications of inanimate objects or effects; reinterpretations of traditional Scottish folklore; hoaxes; and exotic species of large animals.

Misidentification of common animals

Bird wakes

There are wake sightings that occur when the loch is dead calm with no boat nearby. A bartender named David Munro claims to have witnessed a wake he believed was a creature zigzagging, diving, and reappearing. (There were 26 other witnesses from a nearby car park.) Some sightings describe the onset of a V-shaped wake, as if there were something underwater. Moreover, many wake sightings describe something not conforming to the shape of a boat. Under dead calm conditions, a creature too small to be visible to the naked eye can leave a clear v-shaped wake. In particular, a group of swimming birds can give a wake and the appearance of an object. A group of birds can leave the water and then land again, giving a sequence of wakes like an object breaking the surface, which Dick Raynor says is a possible explanation for his film.

Eels

A giant eel was actually one of the first suggestions made. Eels are found in Loch Ness, and an unusually large eel would fit many sightings. This has been described as a conservative explanation. Eels are not known to protrude swanlike from the water and thus would not account for the head and neck sightings. Dinsdale dismissed the proposal because eels move in a side-to-side undulation.

On 2 May 2001, two conger eels were found on the shore of the loch; however, as conger eels are saltwater animals and Loch Ness is a freshwater body of water, it is believed that they were put there to be seen as "Mini-Nessies".

Elephant

In a 1979 article, California biologist Dennis Power and geographer Donald Johnson claimed that the Surgeon's Photograph was in fact the top of the head, extended trunk and flared nostrils of a swimming elephant, probably photographed elsewhere and claimed to be from Loch Ness. In 2006, palaeontologist and artist Neil Clark similarly suggested that travelling circuses might have allowed elephants to refresh themselves in the loch and that the trunk could therefore be the head and neck, with the elephant's head and back providing the humps. In support of this he provided a painting.

Resident animals

When viewed through a telescope or binoculars with no outside reference, it is difficult to judge the size of an object in the water. Loch Ness has resident otters and pictures of them are given by Binns, which could be misinterpreted. Likewise he gives pictures of deer swimming in Loch Ness, and birds that could be taken as a "head and neck" sighting.

Seals

A number of photographs and a video have confirmed the presence of seals in the loch, for up to months at a time. In 1934 the Sir Edward Mountain expedition analysed film taken the same year and concluded that the monster was a species of seal, which was reported in a national newspaper as "Loch Ness Riddle Solved – Official". A long-necked seal was advocated by Peter Costello for Nessie and for other reputed lake-monsters. R.T. Gould wrote "A grey seal has a long and surprisingly extensible neck; it swims with a paddling action; its colour fits the bill; and there is nothing surprising in its being seen on the shore of the loch, or crossing a road." This explanation would cover sightings of lake-monsters on land, during which the creature supposedly waddled into the loch upon being startled, in the manner of seals. Seals could also account for sonar traces that act as animate objects. Against this, it has been argued that all known species of pinnipeds are usually visible on land during daylight hours to sunbathe, something that Nessie is not known to do. However seals have been observed and photographed in Loch Ness and the sightings are sufficiently infrequent to allow for occasional visiting animals rather than a permanent colony.

Misidentifications of inanimate objects or effects

Trees

In 1933 the Daily Mirror showed a picture with the following caption 'This queerly-shaped tree-trunk, washed ashore at Foyers may, it is thought, be responsible for the reported appearance of a "Monster"'. (Foyers is on Loch Ness.)

In a 1982 series of articles for New Scientist, Dr Maurice Burton proposed that sightings of Nessie and similar creatures could actually be fermenting logs of Scots pine rising to the surface of the loch's cold waters. Initially, a rotting log could not release gases caused by decay, because of high levels of resin sealing in the gas. Eventually, the gas pressure would rupture a resin seal at one end of the log, propelling it through the water—and sometimes to the surface. Burton claimed that the shape of tree logs with their attendant branch stumps closely resemble various descriptions of the monster.

Four Scottish lochs are very deep, including Morar, Ness and Lomond. Only the lochs with pinewoods on their shores have monster legends; Loch Lomond—with no pinewoods—does not. Gaseous emissions and surfactants resulting from the decay of the logs can cause the foamy wake reported in some sightings. Indeed, beached pine logs showing evidence of deep-water fermentation have been found. On the other hand, there are believers who assert that some lakes do have reports of monsters, despite an absence of pinewoods; a notable example would be the Irish lough monsters.

Seiches and wakes

Loch Ness, because of its long, straight shape, is subject to some unusual occurrences affecting its surface. A seiche is a large, regular oscillation of a lake, caused by a water reverting to its natural level after being blown to one end of the lake. The impetus from this reversion continues to the lake's windward end and then reverts back. In Loch Ness, the process occurs every 31.5 minutes.

Boat wakes can also produce strange effects in the loch. As a wake spreads and divides from a boat passing the centre of the loch, it hits both sides almost simultaneously and deflects back to meet again in the middle. The movements interact to produce standing waves that are much larger than the original wake, and can have a humped appearance. By the time this occurs, the boat has passed and the unusual waves are all that can be seen.

Optical effects

Wind conditions can give a slightly choppy and thus matte appearance to the water, with occasional calm patches appearing as dark ovals (reflecting the mountains) from the shore, which can appear as humps to visitors unfamiliar with the loch. In 1979, Lehn showed that atmospheric refraction could distort the shape and size of objects and animals, and later showed a photograph of a rock mirage on Lake Winnipeg that looked like a head and neck.

Seismic gas

The Italian geologist Luigi Piccardi has proposed geological explanations for some ancient legends and myths. He pointed out that in the earliest recorded sighting of a creature, the Life of St. Columba, the creature's emergence was accompanied "cum ingenti fremitu" (with very loud roaring). The Loch Ness is located along the Great Glen Fault, and this could be a description of an earthquake. Furthermore, in many sightings, the report consists of nothing more than a large disturbance on the surface of the water. This could be caused by a release of gas from through the fault, although it could easily be mistaken for a large animal swimming just below the surface.

Binns concludes that it would be unwise to put forward a single explanation of the monster, and probably a wide range of natural phenomena have been mistaken for the monster at times: otters, swimming deer, unusual waves. However, he adds that this also touches on some issues of human psychology, and the ability of the eye to see what it wants to see.

Folklore

According to the Swedish naturalist and author Bengt Sjögren (1980), present day beliefs in lake monsters such as Nessie are associated with the old legends of kelpies. He claims that the accounts of loch monsters have changed over the ages, originally describing creatures with a horse-like appearance; they claimed that the "kelpie" would come out of the lake and turn into a horse. When a tired traveller would get on the back of the kelpie, it would gallop into the loch and devour its prey. This myth successfully kept children away from the loch, as was its purpose. Sjögren concludes that the kelpie legends have developed into current descriptions of lake-monsters, reflecting modern awareness of plesiosaurs. In other words, the kelpie of folklore has been transformed into a more realistic and contemporary notion of the creature. Believers counter that long-dead witnesses could only compare the creature to that with which they were familiar, and they were not familiar with plesiosaurs.

Specific mention of the kelpie as a water horse in Loch Ness was given in a Scottish newspaper in 1879, and was commemorated in the title of a book Project Water Horse by Tim Dinsdale.

Hoaxes

The Loch Ness monster phenomenon has seen several attempts to hoax the public, some of which were very successful. Other hoaxes were revealed rather quickly by the perpetrators, or exposed after diligent research. A few examples are mentioned below.

In August 1933, Italian journalist Francesco Gasparini submitted what he claims was the first news article on the Loch Ness monster. In 1959, he confessed to taking a sighting of a "strange fish" and expanding on it by fabricating eye witness accounts. "I had the inspiration to get hold of the item about the strange fish. The idea of the monster had never dawned on me, but then I noted that the strange fish would not yield a long article, and I decided to promote the imaginary being to the rank of monster without further ado."

In the 1930s, a big game hunter named Marmaduke Wetherell went to Loch Ness to look for the Loch Ness Monster. He claimed to have found some footprints but when the footprints were sent to scientists for analysis, they turned out to be hippopotamus footprints. A prankster had used a hippopotamus foot umbrella stand to make the footprints.

In 1972 a team of zoologists from Yorkshire's Flamingo Park Zoo had gone out in search of the legendary monster and soon discovered a large body floating in the water. The corpse, was 16–18 feet long and weighed up to 1.5 tonnes, described by the Press Association as having "a bear's head and a brown scaly body with clawlike fins." The creature was put in a van to be taken away for testing, whereupon police chased them down and took the cadaver under an act of parliament which prohibits the removal of "unidentified creatures" from Loch Ness. But it was later revealed that Flamingo Park's education officer John Shields had shaved the whiskers and otherwise disfigured a bull elephant seal which had died the week before, and dumped it in Loch Ness to dupe his colleagues.

On 2 July 2003, Gerald McSorely found a fossil supposedly belonging to Nessie when he tripped and fell into the loch. After examination, it became clear that the fossil wasn't from Loch Ness and that it had been planted there.

THE YETI


Purported Yeti scalp in Khumjung monastery.

Wiki:

The Yeti or Abominable Snowman is an ape-like cryptid said to inhabit the Himalayan region of Nepal, India and Tibet. The names Yeti and Meh-Teh are commonly used by the people indigenous to the region, and are part of their history and mythology. Stories of the Yeti first emerged as a facet of Western popular culture in the 19th century.

The scientific community generally regards the Yeti as a legend, given the lack of conclusive evidence, yet it remains one of the most famous creatures of cryptozoology. The Yeti may be considered a sort of parallel to the Bigfoot of North America.

Supposed photo of a Yeti taken in 1986.

Wiki:

The frequency of reports increased during the early 20th century, when Westerners began making determined attempts to scale the many mountains in the area and occasionally reported seeing odd creatures or strange tracks.

In 1925, N. A. Tombazi, a photographer and member of the Royal Geographical Society, writes that he saw a creature at about 15,000 ft (4,600 m) near Zemu Glacier. Tombazi later wrote that he observed the creature from about 200 to 300 yd (180 to 270 m), for about a minute. "Unquestionably, the figure in outline was exactly like a human being, walking upright and stopping occasionally to pull at some dwarf rhododendron bushes. It showed up dark against the snow, and as far as I could make out, wore no clothes." About two hours later, Tombazi and his companions descended the mountain and saw the creature's prints, described as "similar in shape to those of a man, but only six to seven inches long by four inches wide... The prints were undoubtedly those of a biped."

Western interest in the Yeti peaked dramatically in the 1950s. While attempting to scale Mount Everest in 1951, Eric Shipton took photographs of a number of large prints in the snow, at about 6,000 m (20,000 ft) above sea level. These photos have been subject to intense scrutiny and debate. Some argue they are the best evidence of Yeti's existence, while others contend the prints are those of a mundane creature that have been distorted by the melting snow. It should also be noted that Eric Shipton was a notorious practical joker.

Peter Byrne reported finding a yeti footprint in 1948, in northern Sikkim, India near the Zemu Glacier, while on holiday from a Royal Air Force assignment in India.

In 1953, Sir Edmund Hillary and Tenzing Norgay reported seeing large footprints while scaling Mount Everest. Hillary would later discount Yeti reports as unreliable. In his first autobiography Tenzing said that he believed the Yeti was a large ape, and although he had never seen it himself his father had seen one twice, but in his second autobiography he said he had become much more skeptical about its existence.

During the Daily Mail Snowman Expedition of 1954, the mountaineering leader John Angelo Jackson made the first trek from Everest to Kanchenjunga in the course of which he photographed symbolic paintings of the Yeti at Tengboche gompa. Jackson tracked and photographed many footprints in the snow, most of which were identifiable. However, there were many large footprints which could not be identified. These flattened footprint-like indentations were attributed to erosion and subsequent widening of the original footprint by wind and particles.

Wiki:

Possible explanations

Misidentification of Himalayan wildlife has been proposed as an explanation for some Yeti sightings, including the Chu-Teh, a Langur monkey living at lower altitudes, the Tibetan Blue Bear, the Himalayan Brown Bear or Dzu-Teh, also known as the Himalayan Red Bear. Some have also suggested the Yeti could actually be a human hermit.

One well publicized expedition to Bhutan reported that a hair sample had been obtained that, after DNA analysis by Professor Bryan Sykes, could not be matched to any known animal.[50] Analysis completed after the media release, however, clearly showed that the samples were from the Brown Bear (Ursus arctos) and the Asiatic Black Bear (Ursus thibetanus).

In 1986, South Tyrolean mountaineer Reinhold Messner claimed to have a face-to-face encounter with a Yeti. He has since written a book, My Quest for the Yeti, and claims to have actually killed one. According to Messner, the Yeti is actually the endangered Himalayan Brown Bear, Ursus arctos isabellinus, that can walk upright or on all fours.

In 2003, Japanese mountaineer Makoto Nebuka published the results of his twelve year linguistic study postulating that the word "Yeti" is actually a corruption of the word "meti", a regional dialect term for "bear". Nebuka claims that the ethnic Tibetans fear and worship the bear as a supernatural being.[53] Nebuka's claims were subject to almost immediate criticism, and he was accused of linguistic carelessness. Dr. Raj Kumar Pandey, who has researched both Yetis and mountain languages, said "it is not enough to blame tales of the mysterious beast of the Himalayas on words that rhyme but mean different things."

Some speculate that these reported creatures could be present-day specimens of the extinct giant ape Gigantopithecus. However, while the Yeti is generally described as bipedal, most scientists believe Gigantopithecus to have been quadrupedal, and so massive that, unless it evolved specifically as a bipedal ape (like Oreopithecus and the hominids), walking upright would have been even more difficult for the now extinct primate than it is for its extant quadrupedal relative, the orangutan.

BIGFOOT:


Frame 352 from the Patterson-Gimlin film, alleged by Roger Patterson and Robert Gimlin to show a cryptid called Bigfoot, and by some others to show a man in an ape suit.

Wiki:

Bigfoot, also known as Sasquatch, is an ape-like cryptid that purportedly inhabits forests, mainly in the Pacific Northwest region of North America. Bigfoot is usually described as a large, hairy, bipedal humanoid. The term "Sasquatch" is an anglicized derivative of the word "Sésquac" which means "wild man" in a Salish Native American language.

Most scientists discount the existence of Bigfoot and consider it to be a combination of folklore, misidentification, and hoax, rather than a living animal, in part because of the large numbers thought necessary to maintain a breeding population. However some scientists such as Jane Goodall, Jeffrey Meldrum, John Napier and Grover Krantz have expressed interest and belief in the creature. Meldrum expressed the opinion that evidence collected of alleged Bigfoot encounters warrants further evaluation and testing

Photo of an unidentified animal the Bigfoot Research Organization claims is a "juvenile Sasquatch".

Wiki:

Bigfoot is described in reports as a large hairy ape-like creature, ranging between 6–10 feet (2–3 m) tall, weighing in excess of 500 pounds (230 kg), and covered in dark brown or dark reddish hair. Alleged witnesses have described large eyes, a pronounced brow ridge, and a large, low-set forehead; the top of the head has been described as rounded and crested, similar to the sagittal crest of the male gorilla. Bigfoot is commonly reported to have a strong, unpleasant smell by those who claim to have encountered it. The enormous footprints for which it is named have been as large as 24 inches (60 cm) long and 8 inches (20 cm) wide. While most casts have five toes—like all known apes—some casts of alleged Bigfoot tracks have had numbers ranging from two to six.[11] Some have also contained claw marks, making it likely that a portion came from known animals such as bears, which have five toes and claws. Some proponents have also claimed that Bigfoot is omnivorous and mainly nocturnal.

Distribution of reported Bigfoot sightings in North America.

Wiki:

About a third of all reports of Bigfoot sightings are concentrated in the Pacific Northwest, with most of the remaining reports spread throughout the rest of North America. Some Bigfoot advocates, such as cryptozoologist John Willison Green, have postulated that Bigfoot is a worldwide phenomenon. The most notable reports include:

1924: Fred Beck claimed that he and four other miners were attacked one night in July 1924, by several "apemen" throwing rocks at their cabin in an area later called Ape Canyon, Washington. Beck said the miners shot and possibly killed at least one of the creatures, precipitating an attack on their cabin, during which the creatures bombarded the cabin with rocks and tried to break in. The supposed incident was widely reported at the time. Beck wrote a book about the alleged event in 1967, in which he argued that the creatures were mystical beings from another dimension, claiming that he had experienced psychic premonitions and visions his entire life of which the apemen were only one component. Speleologist William Halliday argued in 1983 that the story arose from an incident in which hikers from a nearby camp had thrown rocks into the canyon. There are also local rumors that pranksters harassed the men and planted faked footprints.

1941: Jeannie Chapman and her children said they had escaped their home when a 7.5 feet (2.3 m) tall Sasquatch approached their residence in Ruby Creek, British Columbia.

1958: Bulldozer operator Jerry Crew took to a newspaper office a cast of one of the enormous footprints he and other workers had seen at an isolated work site at Bluff Creek, California. The crew was overseen by Wilbur L. Wallace, brother of Raymond L. Wallace. After Ray Wallace's death, his children came forward with a pair of 16-inch (41 cm) wooden feet, which they said their father had used to fake the Bigfoot tracks in 1958. Wallace is poorly regarded by many Bigfoot proponents. John Napier wrote, "I do not feel impressed with Mr. Wallace's story" regarding having over 15,000 feet (4,600 m) of film showing Bigfoot.

1967: Roger Patterson and Robert Gimlin reported that on October 20 they had captured a purported Sasquatch on film at Bluff Creek, California. This came to be known as the Patterson-Gimlin film. Many years later, Bob Heironimus, an acquaintance of Patterson's, said that he had worn an ape costume for the making of the film.

2007: On September 16, 2007, hunter Rick Jacobs captured an image of a supposed Sasquatch by using an automatically triggered camera attached to a tree, prompting a spokesperson for the Pennsylvania Game Commission to say that it was likely an image of "a bear with a severe case of mange." The photo was taken near the town of Ridgway, Pennsylvania, in the Allegheny National Forest.

Proposed explanations for sightings

Various types of creatures have been suggested to explain both the sightings and what type of creature Bigfoot would be if it existed. The scientific community typically attributes sightings to either hoaxes or misidentification of known animals and their tracks. While cryptozoologists generally explain Bigfoot as an unknown ape, some believers in Bigfoot attribute the phenomenon to UFOs or other paranormal causes. A minority of proponents of a natural explanation have attributed Bigfoot to animals that are not apes such as the giant ground sloth.

Misidentification

In 2007, the Pennsylvania Game Commission said that photos the Bigfoot Field Researchers Organization claimed showed a juvenile Bigfoot were most likely of a bear with mange. Jeffrey Meldrum, on the other hand, said the limb proportions of the suspected juvenile in question were not bear-like, and stated that he felt they were "more like a human."

A tale presented in Theodore Roosevelt's 1892 book The Wilderness Hunter (reprinted in his 1900 book Hunting the Grisly and Other Sketches) describing an encounter between two hunters and a violent bear is sometimes presented by Bigfoot proponents as historical evidence of the creature's existence.

Hoaxes

Both scientists and Bigfoot believers agree that many of the sightings are hoaxes or misidentified animals. Cryptozoologists Loren Coleman and Diane Stocking have estimated that as many as 70 to 80 percent of sightings are not real.

Bigfoot sightings or footprints are often demonstrably hoaxes. Author Jerome Clark argues that the "Jacko affair", involving an 1884 newspaper report of an apelike creature captured in British Columbia, was a hoax. Citing research by John Green, who found that several contemporary British Columbia newspapers regarded the alleged capture as very dubious, Clark notes that the Mainland Guardian of New Westminster, British Columbia, wrote, "Absurdity is written on the face of it."

On July 14, 2005, Tom Biscardi, a long-time Bigfoot enthusiast and CEO of Searching for Bigfoot Inc., appeared on the Coast to Coast AM paranormal radio show and announced that he was "98% sure that his group will be able to capture a Bigfoot which they have been tracking in the Happy Camp, California area." A month later, Biscardi announced on the same radio show that he had access to a captured Bigfoot and was arranging a pay-per-view event for people to see it. Biscardi appeared on Coast to Coast AM again a few days later to announce that there was no captive Bigfoot. Biscardi blamed an unnamed woman for misleading him, and the show's audience for being gullible.

On July 9, 2008, Rick Dyer and Matthew Whitton posted a video to YouTube claiming that they had discovered the body of a dead Sasquatch in a forest in northern Georgia. Tom Biscardi was contacted to investigate. Dyer and Whitton received $50,000 from Searching for Bigfoot, Inc., as a good faith gesture. The story of the men's claims was covered by many major news networks, including BBC, CNN, ABC News, and Fox News. Soon after a press conference, the alleged Bigfoot body arrived in a block of ice in a freezer with the Searching for Bigfoot team. When the contents were thawed, it was discovered that the hair was not real, the head was hollow, and the feet were rubber. Dyer and Whitton subsequently admitted it was a hoax after being confronted by Steve Kulls, executive director of Squatchdetective.com.

Gigantopithecus


Fossil jaw of Gigantopithecus blacki, an extinct primate

Bigfoot proponents Grover Krantz and Geoffrey Bourne believe that Bigfoot could be a relict population of Gigantopithecus. Bourne contends that as most Gigantopithecus fossils are found in China, and as many species of animals migrated across the Bering land bridge, it is not unreasonable to assume that Gigantopithecus might have as well.

The Gigantopithecus hypothesis is generally considered entirely speculative. Gigantopithecus fossils are not found in the Americas. As the only recovered fossils are of mandibles and teeth, there is some uncertainty about Gigantopithecus's locomotion. Krantz has argued, based on his extrapolation of the shape of its mandible, that Gigantopithecus blacki could have been bipedal. However, the relevant part of mandible is not present in any fossils. The mainstream view is that Gigantopithecus was quadrupedal, and it has been argued that Gigantopithecus's enormous mass would have made it difficult for it to adopt a bipedal gait.

Matt Cartmill presents another problem with the Gigantopithecus hypothesis: "The trouble with this account is that Gigantopithecus was not a hominin and maybe not even a crown-group hominoid; yet the physical evidence implies that Bigfoot is an upright biped with buttocks and a long, stout, permanently adducted hallux. These are hominin autapomorphies, not found in other mammals or other bipeds. It seems unlikely that Gigantopithecus would have evolved these uniquely hominin traits in parallel."

Bernard G. Campbellin wrote: "That Gigantopithecus is in fact extinct has been questioned by those who believe it survives as the Yeti of the Himalayas and the Sasquatch of the north-west American coast. But the evidence for these creatures is not convincing."

Extinct hominidae

A species of Paranthropus, such as Paranthropus robustus, with its crested skull and bipedal gait, was suggested by primatologist John Napier and anthropologist Gordon Strasenburg as a possible candidate for Bigfoot's identity, despite the fact that fossils of Paranthropus are found only in Africa.

Michael Rugg, of the Bigfoot Discovery Museum, presented a comparison between human, Gigantopithecus and Meganthropus skulls (reconstructions made by Grover Krantz) in episodes 131 and 132 of the Bigfoot Discovery Museum Show. He favorably compares a modern tooth suspected of coming from a bigfoot to the Meganthropus fossil teeth, noting the worn enamel on the occlusal surface. The Meganthropus fossils originated from Asia, the tooth was found in the Pacific Northwest.

Some suggest Neanderthal or Homo erectus to be the creature but no remains of either species are found in the New World.

Wiki:

The scientific community discounts the existence of Bigfoot, as there is no evidence supporting the survival of such a large, prehistoric ape-like creature. The evidence that does exist points more towards a hoax or delusion than to sightings of a genuine creature. In a 1996 USA Today article titled "Bigfoot Merely Amuses Most Scientists", Washington State zoologist John Crane says, "There is no such thing as Bigfoot. No data other than material that's clearly been fabricated has ever been presented." In addition to the lack of evidence, scientists cite the fact that Bigfoot is alleged to live in regions unusual for a large, nonhuman primate, i.e., temperate latitudes in the northern hemisphere; all recognized nonhuman apes are found in the tropics of Africa and Asia. Thus, as with other proposed megafauna cryptids, climate and food supply issues would make such a creature's survival in reported habitats unlikely. Furthermore, great apes are not found in the fossil record in the Americas, and no Bigfoot remains have ever been found. Indeed, scientific consensus is that the breeding population of such an animal would be so large that it would account for many more purported sightings than currently occur, making the existence of such an animal an almost certain impossibility.

A few scientists have been less skeptical about the claims of the existence of sasquatch. Jeffrey Meldrum characterizes the search for Sasquatch as "a valid scientific endeavor" and says that the fossil remains of an ancient giant ape called Gigantopithecus could turn out to be ancestors of today’s commonly known Bigfoot. John Napier asserts that the scientific community's attitude towards Bigfoot stems primarily from insufficient evidence. Other scientists who have shown varying degrees of interest in the legend are anthropologist David Daegling, field biologist George Shaller, Russell Mittermeier, Daris Swindler, Esteban Sarmiento, and discredited racial anthropologist Carleton S. Coon. Jane Goodall, in a September 27, 2002 interview on National Public Radio's "Science Friday", expressed her ideas about the existence of Bigfoot. First stating "I'm sure they exist", she later went on to say, chuckling, "Well, I'm a romantic, so I always wanted them to exist", and finally: "You know, why isn't there a body? I can't answer that, and maybe they don't exist, but I want them to." However, the vast majority of evolutionary biologists, anthropologists and paleontologists completely dismiss the possibility of the existence of sasquatch.