Потребителски вход

Запомни ме | Регистрация
Постинг
16.12.2015 18:10 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part1 Mammals ch.3 The Largest Beasts to Walk the Earth
Автор: valentint Категория: Забавление   
Прочетен: 2926 Коментари: 0 Гласове:
0

Последна промяна: 03.07 22:22


The Largest Beasts to Walk the Earth

image

It seems that at least once a year, news of the “largest dinosaur ever found” makes headlines. That’s because almost all the contenders for the biggest saurian are so fragmentary that settling on an uncontested victor is almost impossible, not to mention that new discoveries are being made all the time. There hasn’t been as much of a debate about fossil mammals. For over a century, Paraceratherium – a 26-foot-long, 15 ton, hornless rhino – has been cited as the biggest of the big beasts. But, according to a new paper by Asier Larramendi, ancient elephants are in close competition for the title of the largest mammals to ever walk the Earth.

Such contests rely on how they’re measured, of course. Part of what makes Paraceratherium seem so large is its elongated neck. In terms of tonnage, however, Felisa Smith and colleagues pointed out that the largest prehistoric proboscideans – such as the anchor-tusked Deinotherium – were likely heavier. (It’s similar with sauropods – does Supersaurus hold the title of Biggest Dinosaur because of it was a bit longer, or does Argentinosaurus because it weighed more?) Giants are made by how you measure them.  In this case, Larramendi drew from photos, measurements, and reconstructions of fossil and living elephants to come up with estimates of body mass and shoulder height.
Starting with the bones, Larramendi created virtual restorations of 24 different elephant species. The point, aside from trying to correct errors in articulation that are sometimes made when these animals are mounted in museums, was to restore the elephants as accurately as possible in order to estimate their volume and, from that, their body mass. Some researchers use a different methodology for these sorts of estimates – focused on estimating how body shape changes with size – but Larramendi prefers the volumetric method.
Larramendi selected elephants from various times in their 60 million year record. The very early Eritherium azzouzorum, for example, may have weighed 11-13 pounds and been a little more than half a foot high at the shoulder. From such a small start, elephants eventually attained truly enormous sizes. Larramendi calculates the largest Deinotherium weighed 13 tons and stood over 13 feet high at the shoulder. Others were bigger still. The mastodon Mammut borsoni, Larramendi calculates, would have weighed over 15 tons and been almost 13 and a half feet tall at the shoulder, and, based on some scrappy material, Larramendi estimates that the elephant Palaeoloxodon namadicus would have reached 24 tons and an imposing 16 feet at the shoulder.

image

Palaeoloxodon namadicus or the Asian straight-tusked elephant, was a species of prehistoric elephant that ranged throughout
Pleistocene Asia, from India (where it was first discovered) to Japan, where the indigenous Neolithic cultures hunted that particular subspecies for food. It is a descendant of the straight-tusked elephant.
Some authorities regard it to be a subspecies of Palaeoloxodon antiquus, the straight-tusked elephant, due to extreme similarities of the tusks.
Several studies have attempted to estimate the size of the Asian straight-tusked elephants, as well as other prehistoric proboscideans, usually using comparisons of thigh bone length and knowledge of relative growth rates to estimate the size of incomplete skeletons.
image

One partial skeleton found in India in 1905 had thigh bones that likely measured 160 centimetres (5.2 ft) when complete, suggesting a total shoulder height of 4.3 metres (14 ft) and weight of 14 tonnes (14 long tons; 15 short tons) for this individual elephant.
Two partial thigh bones were found in the 19th century and would have measured 155 cm (5.1 ft) when complete. A fragment from the same locality was said to be almost a quarter larger; volumetric analysis then yields a size estimate of 5 metres (16 ft) tall at the shoulders and possibly 22 tonnes (24 short tons). This would make P. namadicus the largest land mammal of all time, surpassing the largest indricotheres. (units:tonnes = 1000 kilograms, long ton= 2,240 pounds, short ton=2000 pounds)

I present your contenders:

Paraceratherium transouralicum (originally in Indricotherium) image
Paraceratherium is one of the largest known land mammals that have ever existed, but its exact size is unclear because of the lack of complete specimens. Early estimates of 30 tonnes (66,000 lb) are now considered exaggerated; it may have been in the range of 15 to 20 tonnes (33,000 to 44,000 lb) at maximum, and as low as 11 tonnes (24,000 lb) on average. Calculations have mainly been based on fossils of P. transouralicum because this species is known from the most complete remains.Estimates have been based on skull, teeth, and limb bone measurements, but the known bone elements are represented by individuals of different sizes, so all skeletal reconstructions are composite extrapolations, resulting in several weight ranges.Its total body length was estimated as 8.7 m (28.5 ft) from front to back by Granger and Gregory in 1936, and 7.4 m (24.3 ft) by the Soviet palaeontologist Vera Gromova in 1959, but the former estimate is now considered exaggerated. The weight of Paraceratherium was similar to that of some extinct proboscideans, with the largest complete skeleton known belonging to the steppe mammoth (Mammuthus trogontherii).Despite its roughly equivalent mass, Paraceratherium might have been taller than any proboscidean.Its shoulder height was estimated as 5.25 m (17.2 ft) at the shoulders by Granger and Gregory, but 4.8 m (15.7 ft) by the American palaeontologist Gregory S. Paul in 1997.The neck was estimated at 2 to 2.5 m (6.6 to 8.2 ft) long by the palaeontologists Michael P. Taylor and Mathew J. Wedel in 2013.
Paraceratherium huangheense differs from P. bugtiense only in the anatomy of the rear portion of the jaw, as well as its larger size.

The largest individual known was estimated at 4.8 m (16 ft) tall at the shoulders, 8.0 m (26.2 ft) in length from nose to rump, and 16 t (18 tons) in weight. Paraceratherium is an extinct
genus of hornless rhinoceros, and the largest terrestrial mammal that has ever existed. It lived from the early to late Oligocene epoch (34–23 million years ago); its remains have been found across Eurasia between China and the former Yugoslavia. Paraceratherium is classified as a member of the hyracodont subfamily Indricotheriinae. Paraceratherium means "near the hornless beast", in reference to Aceratherium, a genus that was once thought similar.
The exact size of Paraceratherium is unknown because of the incompleteness of the fossils. Its weight is estimated to have been 15 to 20 tonnes (33,000 to 44,000 lb) at most; the shoulder height was about 4.8 metres (16 feet), and the length about 7.40 metres (24.3 feet). The legs were long and pillar-like. The long neck supported a skull that was about 1.3 metres (4.3 ft) long. It had large, tusk-like incisors and a nasal incision that suggests it had a prehensile upper lip or proboscis. The lifestyle of Paraceratherium may have been similar to that of modern large mammals such as the elephants and extant rhinoceroses. Because of its size, it would have had few predators and a slow rate of reproduction. Paraceratherium was a browser, eating mainly leaves, soft plants, and shrubs. It lived in habitats ranging from arid deserts with a few scattered trees to subtropical forests. The reasons for the animal"s extinction are unknown, but various factors have been proposed.


Mammuthus trogontherii (Steppe mammoth)  presented by the subspecies Mammuthus sungari
image

For a little over fifty years Mammuthus sungari, perhaps better known as the Songhua River mammoth, has been regarded as being the largest known species of mammoth, and possibly the second largest terrestrial mammal of all time (the title of largest currently goes to Paraceratherium).
In 1959 Zhou, M. Z described what he called a new species of mammoth, M. sungari,that gained recent notoriety as the largest proboscidean due to a 5.3 metres (17.4 ft) tall and 9.1 metres (29.9 ft) long composite skeletal mount based on two individuals found in 1980. However, Wei et al. (2010), who restudied the fossils referred to M sungari, considered this species to be a junior synonym of M. trogontherii. The authors state that some of the fossils are referrable to M. trogontherii, while the others can be referred to M. primigenius, according to morphological characters and measurements.
As such the future of M. sungari as a distinct species is now in doubt and its most likely that from now on M. trogontherii will be referred to as the largest mammoth species, which also means that M. trogontherii will also be considered to be larger than M. imperator (imperial mammoth) which was previously considered to be larger than M. trogontherii.
image

According to the Ibaraki Nature museum, the Songhua River Mammoth -- also known as the Shokako Mammoth in Japanese -- (Mammuthus sungari) was the largest mammoth in the world, surpassing even the Imperial Mammoth in size. The mounted skeleton at the museum reaches an overall height of 5.3 meters and a length of 9.1 meters, with hips more than 2.2 meters wide and tusks 3.2 meters in length. This specimen could have weighed more than 20 metric tons, as heavy as Paraceratherium, making it one of the largest land mammals of all time.


Zygolophodon (Mammut borsoni)
image
Zygolophodonis an extinct genus of African, Asian, North American and European mastodon that lived during the Miocene and Pliocene epochs. It may have evolved from Tetralophodon. While collecting fossils in the Clarno Formation of Oregon during 1941, noted paleobotanistsAlonzo W. Hancock and Chester A. Arnold recovered the most complete Zygolophodon skull known at the time.
It was one of the largest terrestrial mammals of all time. With a shoulder height of 4.1-4.8 metres (13.5 ft-15ft) and a weight of 14–16 tonnes (15–18 short tons), it was approached the size of Paraceratherium, and was heavier than several sauropod dinosaurs.
A monstrous Mastodon which is nearly 3 times heavier than the extant African Elephant,weighing about 16 tonnes.It is the king of Tuskers.Zygolophodon had the longest tusks of any Proboscidean measuring upto 16 feet ! The Columbian Mammoth also had tusks upto 16 feet but it"s tusks were curved.
This animal was close to being the largest land mammal.
Two of the known specimens are not fully grown.If it had lived longer,it could surpass 18 tonnes.



Palaeoloxodon namadicus
image
Palaeoloxodon namadicus or the Asian straight-tusked elephant, was a species of prehistoric elephant that ranged throughout Pleistocene Asia, from India (where it was first discovered) to Japan, where the indigenous Neolithic cultures hunted that particular subspecies for food. It is a descendant of the straight-tusked elephant.
Some authorities regard it to be a subspecies of Palaeoloxodon antiquus, the straight-tusked elephant, due to extreme similarities of the tusks. Their skull structure was also different from that of a modern elephant.
Several studies have attempted to estimate the size of the Asian straight-tusked elephants, as well as other prehistoric proboscideans, usually using comparisons of thigh bone length and knowledge of relative growth rates to estimate the size of incomplete skeletons.
One partial skeleton found in India in 1905 had thigh bones that likely measured 160 centimetres (5.2 ft) when complete, suggesting a total shoulder height of 4.3 metres (14 ft) and weight of 14 tonnes (14 long tons; 15 short tons) for this individual elephant.
Two partial thigh bones were found in the 19th century and would have measured 155 cm (5.1 ft) when complete. A fragment from the same locality was said to be almost a quarter larger; volumetric analysis then yields a size estimate of 5 metres (16 ft) tall at the shoulder and 22 tonnes (24 short tons) in weight. This makes P. namadicus the largest land mammal of all time, surpassing the largest indricotheres and up to twice the size of the well-known dinosaur
Diplodocus carnegii. (units:tonnes = 1000 kilograms, long ton= 2,240 pounds, short ton=2000 pounds)



 




















 

 




Гласувай:
0
0



Няма коментари
Търсене

За този блог
Автор: valentint
Категория: Политика
Прочетен: 490727
Постинги: 181
Коментари: 17
Гласове: 15
Календар
«  Август, 2019  
ПВСЧПСН
1234
567891011
12131415161718
19202122232425
262728293031