American lion (Panthera leo atrox)

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First I will post the reference materials:

North American megafauna

The American lion (Panthera atrox),

The American lion (Panthera atrox), also known as the "North American lion", or "American cave lion", is an extinct pantherine cat that lived in North America during the Pleistocene epoch and the early Holocene epoch, about 340,000 to 11,000 years ago. Its fossils have been excavated from Alaska to Mexico. Genetic analysis has shown that the American lion and the Late Pleistocene Eurasian cave lion (Panthera spelaea) are sister lineages. It was about 25% larger than the modern lion, making it one of the largest known felids.

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The American lion was initially considered a distinct species of Pantherinae, and designated as Panthera atrox /ˈpænθərə ˈætrɒks/, which means "cruel" or "fearsome panther" in Latin. Some paleontologists accepted this view, but others considered it to be a type of lion closely related to the modern lion (Panthera leo) and its extinct relative, the Eurasian cave lion (Panthera leo spelaea or P. spelaea). It was later assigned as a subspecies of P. leo (P. leo atrox) rather than as a separate species. Most recently, both spelaea and atrox have been treated as full species.

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The American lion is estimated to have measured 1.6 to 2.5 m (5 ft 3 in to 8 ft 2 in) from the tip of the nose to the base of the tail and stood 1.2 m (3.9 ft) at the shoulder. Thus, it was smaller than its contemporary competitor, the giant short-faced bear, which was the largest carnivoran of North America at the time, and larger than the saber-toothed cat, Smilodon fatalis, which may have weighed up to 280 kg (620 lb). In 2008, the American lion was estimated to weigh up to 420 kg (930 lb). A study in 2009 showed an average weight of 256 kg (564 lb) for males and 351 kg (774 lb) for the largest specimen analyzed. A study in 2012 estimated a range of 235–523 kg (518–1,153 pounds) for males and 175–365 kg (386–805 pounds) for females, which suggests that the lion was heavier than Smilodon.

About 80 American lion individuals have been recovered from the La Brea Tar Pits in Los Angeles, so their morphology is well known. Their features strongly resemble those of modern lions, but they were considerably larger, similar to P. spelaea and the Pleistocene Natodomeri lion of eastern Africa.

Preserved skin remains found with skeletal material thought by its describers to be from the American lion in caves in the Argentine Patagonia indicate that the animal was reddish in color. Cave paintings from El Ceibo in the Santa Cruz Province of Argentina seem to confirm this, and reduce the possibility of confusion with fossil jaguars, as similar cave paintings accurately depict the jaguar as yellow in color.

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For Comparison:

Lion

Average Female lions Male lions
Head-and-body length 63–72 in 72–82 in
Tail length 28.3–35.2 in 32.5–36.8 in
Weight 261.0–316.4 lb in Southern Africa 411.3–496.0 lb in Southern Africa
263 lb in East Africa 386 lb in East Africa
240–260 lb in India 350–420 lb in IndiaTiger

The data on size was recorded differently.

There is notable sexual dimorphism between male and female tigers, with the latter being consistently smaller.
Average                     Female Tigers                   Male Tigers
Skull length 0.879 to 1.043 ft 12.4 to 15.1 in
Head-and-body-tail length 6.56 to 9.02 ft 8.2 to 12.8 ft
Tail length alone 24 to 43 in 24 to 43 in
Weight 143 to 368 lb 200 and 660 lb

Hybirds

Liger

The liger is a hybrid offspring of a male lion (Panthera leo) and a female tiger (Panthera tigris). The liger has parents in the same genus but of different species. The liger is distinct from the similar hybrid called the tigon, and is the largest of all known extant felines.They enjoy swimming, which is a characteristic of tigers, and are very sociable like lions. Notably, ligers typically grow larger than either parent species, unlike tigons.

Size and growth

The liger is often believed to be the largest known cat in the world. Males reach a total length of 9.8 to 11.8 ft), which means that they rival even large male lions and tigers in length. Imprinted genes may be a factor contributing to the large size of ligers. These are genes that may or may not be expressed on the parent they are inherited from, and that occasionally play a role in issues of hybrid growth. For example, in some dog breed crosses, genes that are expressed only when maternally-inherited cause the young to grow larger than is typical for either parent breed. This growth is not seen in the paternal breeds, as such genes are normally "counteracted" by genes inherited from the female of the appropriate breed.

Other big cat hybrids can reach similar sizes; the litigon, a rare hybrid of a male lion and a female tigon, is roughly the same size as the liger, with a male named Cubanacan (at the Alipore Zoo in India) reaching 800 lb). The extreme rarity of these second-generation hybrids may make it difficult to ascertain whether they are larger or smaller, on average, than the liger.

It is sometimes wrongly believed that ligers continue to grow throughout their lives due to hormonal issues. It may be that they simply grow far more during their growing years and take longer to reach their full adult size. Further growth in shoulder height and body length is not seen in ligers over six years old, as in both lions and tigers. Male ligers also have the same levels of testosterone on average as an adult male lion, yet are azoospermic in accordance with Haldane's rule. In addition, female ligers may also attain great size, weighing approximately 705 lb and reaching 10 ft long on average, and are often fertile. In contrast, pumapards (hybrids between pumas and leopards) tend to exhibit dwarfism.

Ligers are about the same size as the prehistoric Smilodon populator and American lion.

Hercules, the largest non-obese liger, is recognised by the Guinness Book of World Records as the largest living cat on Earth, weighing 922 lb).

The Valley of the Kings Animal Sanctuary in Wisconsin had a male liger named Nook who weighed over 1,213 lb.

To compare, the records for the lion and tiger in captivity are under 1,100 pounds.

Tigon

A tigon (/ˈtaɪɡən/) or tiglon (/ˈtaɪɡlən/) is the hybrid offspring of a male tiger (Panthera tigris) and a female lion (Panthera leo), they exhibit visible characteristics from both parents: they can have both spots from the mother (lions carry genes for spots - lion cubs are spotted and some adults retain faint markings) and stripes from the father. Any mane that a male tigon may have will appear shorter and less noticeable than a lion's mane and is closer in type to the ruff of a male tiger. It is a common misconception that tigons are smaller than lions or tigers. They do not exceed the size of their parent species because they inherit growth-inhibitory genes from both parents, but they do not exhibit any kind of dwarfism or miniaturization; they often weigh around 400 lb, compared to ligers which often weigh from 710 lb to 1,210 lb.

Guggisberg wrote that ligers and tigons were long thought to be sterile; in 1943, however, a 15-year-old hybrid between a lion and an "Island" tiger was successfully mated with a lion at the Munich Hellabrunn Zoo. The female cub, although of delicate health, was raised to adulthood.

At the Alipore Zoo in India, a tigoness named Rudhrani, born in 1971, was successfully mated to a male Asiatic lion named Debabrata. The rare, second generation hybrid was called a litigon. Rudhrani produced seven litigons in her lifetime. Some of these reached impressive sizes - a litigon named Cubanacan weighed at least 800 lb, stood 4.3 ft at the shoulder, and was 11 ft in total length.

Reports also exist of the similar titigon /ˌtaɪˈtaɪɡən/, resulting from the cross between a female tigon and a male tiger. Titigons resemble golden tigers, but with less contrast in their markings. A tigoness born in 1978, named Noelle, shared an enclosure in the Shambala Preserve with a male Siberian tiger called Anton, due to the keepers' belief that she was sterile. In 1983 Noelle produced a titigon named Nathaniel. As Nathaniel was three - quarters tiger, he had darker stripes than Noelle and vocalized more like a tiger, rather than with the mix of sounds used by his mother. Being only about quarter-lion, Nathaniel did not grow a mane. Nathaniel died of cancer at the age of eight or nine years old. Noelle also developed a severe cancer, that killed her not long after she was diagnosed.