The earliest camels were only the size of rabbits? Learn about the evolution of camels in one article

As we all know, camels have a well-known reputation as "ships of the desert", but in the 40 million years of long evolutionary history of the camel family, they actually have no fate with the desert. Most prehistoric camels lived in a relatively more comfortable environment. Even the most hunger- and thirst-resistant modern camels are not tailored to adapt to the desert.

Camels throughout history

Source: valentint.blog

Early gazelle camels

The earliest known member of the camel family is Poebrodon, which lived in the Middle Eocene. It may have been only the size of a rabbit. Due to the limited known fossil materials, its exact body shape is still unknown.

But soon after the Poebrotherium, a type of light and agile small camel spread across the increasingly open plains of central North America. This was the first unit of the Camelidae family to enter the grasslands - Poebrotherium .

Camel

Source: prehistoric-fauna

The most proud feature of the camel is its long legs, and the proportions of its limbs are similar to those of the gazelles of later times, which can be said to be the ceiling of the running speed of land animals of the same period. The camel has many features similar to those of modern camels, such as the canine shape of the last incisor and the first premolar, which makes the camel have a grinning expression when it opens its mouth.

Source: gifer

In the late Oligocene, the more advanced Stenomylus replaced the proto-camelids. Compared with the more primitive proto-camelids, its molars were larger in proportion and had higher crowns, making it better adapted to grazing on increasingly coarse grasses.

Although there was a significant improvement in teeth, the body shape became smaller and closer to the image of a gazelle. Since the Oligocene, the global climate has gradually turned to dry and cold, and the area of ​​grassland has increased day by day. The ecological niche of early camels is similar to that of gazelles, which enabled them to gain the initiative in the competition with other camels.

In that era, the narrow-molar camel was the most prosperous member of the camel family, but some detailed skeletal features show that it was not the ancestor of modern camels. It gradually declined and eventually became extinct in the Early Miocene.

Narrow-toothed camel

Source: Twitter

Why did the gazelle-shaped camel, which was originally very pleasing in appearance, eventually disappear in the evolutionary dust? This cannot be perfectly explained at present, but it is certain that in the Miocene, the rise of the horse family and the pronghorn family, which were also adapted to the grassland environment, was bound to squeeze the camel family.

When it comes to eating grass, camels are not as efficient as horses in eating grass, and their digestion and absorption abilities are not as good as those of the pronghorn of the ruminant suborder. The camel family, originally pioneers of the grasslands, has fallen into an embarrassing situation. So far, the camel family needs to be further upgraded to cope with the increasingly fierce competition on the North American grasslands.

Early Miocene North America

Source: Wikipedia

Weird giraffe-shaped camel

During the Late Oligocene, the narrow-moth camel coexisted with a small camel called Gentilicamelus, which may be the prehistoric ancestor of modern camels and alpacas.

During the Early Miocene and Middle Miocene, the camel family reached its peak of diversity. More than a dozen genera and species of camels once roamed together in the North American wilderness. The mainstream camels at this time were still almost a strengthened version of the narrow-molar camel, with shorter limbs than modern camels, and they mainly fed on ground grass.

Among these camels, the Oxydactylus camel seems to have predicted the future evolutionary trend and was the first to evolve a long neck in an attempt to eat plants at high altitudes and avoid fighting with other herbivores at low altitudes. Unfortunately, due to its small body, even if its neck is straightened, its height does not exceed that of an adult. It can be said that it has the will but not the strength.

Pointed-toed camel

Source: DeviantArt

The will of the pointy-toed camel was inherited by the more extreme form of the Aepycamelus. Among prehistoric camels, the Aepycamelus can be said to be the camel that most resembles a giraffe.

The most common long-necked tall camel has a head height of up to 3 meters, and the later large tall camel can even have a head height of more than 5 meters, making it the tallest camel at the time . Due to its significant height advantage, there are almost no other herbivores in North America that can compete with the tall camel on the same level.

As a result, the Giraffidae became one of the most stable and long-lived members of the Camelidae in the history of North America, lasting almost 10 million years. Since the Giraffidae never entered North America, this stolen evolutionary strategy was extremely successful. After the Middle Miocene, most of the emerging camels embarked on this long-necked path.

Gaotuo

Source: Wikipedia

But some, like the Florida alligator-tailed camel (Florida taragulus), choose to elongate their faces, making their entire heads look like a cross between a crocodile and a camel.

Florida Alligator Camel

Source: TGStat

A lean camel is bigger than a horse: the camel tribe

Every generation has its own talented people, each of whom leads the trend for hundreds of years. By the end of the Miocene, the subfamily Camelinae, to which modern camels belong, swept across the world and unified the camel kingdom.

The earliest known member is the Western camel (Hesperocamelus) in the early and middle Miocene, which imitated the giraffe-like camels to eat tree branches and leaves, successfully eliminating the herbivorous primitive camels. With the differentiation of the alpaca and camel tribes 16 million years ago.

Let’s talk about the camel family first. The earliest member was the Procamelus, which was only the size of an alpaca. Based on the morphology of its foot bones, it is speculated that the Procamelus had already grown the broad, fleshy pads found on modern camels’ feet. It was also a very long-lived ancient camel and did not become completely extinct until the end of the Miocene 6 million years ago, having lasted for tens of millions of years.

Camelus

Source: Dinopedia

There is a saying that "a skinny camel is bigger than a horse". Camel tribes have produced a variety of giants throughout history. Megatylopus, which existed 10 million years ago, was the earliest giant camel . It was estimated to weigh more than 1 ton, almost the largest and heaviest even-toed ungulate animal in North America at that time. Judging from the shape of its shoulders and back, it was confirmed that it had a hump, but it was not necessarily as tall as today's camels.

Camelus

Source: Dinopedia

By the Pliocene, a group of even larger camels roamed the North American continent, including the giant-footed camel (Titanotylopus), the elephant camel (Gigantocamelus) and the largest camel in North American history - Megacamelus merriami. This camel is estimated to be 3.3 meters tall and weigh more than 2 tons, making it possibly the largest even-toed ungulate in history.

The "huge beast" in evolutionary history

Source: valentint.blog.bg

Today's Bactrian camels and dromedaries seem to have appeared specifically to adapt to the desert . Their long and dense eyelashes can protect their eyes from windy sand; their nostrils that can open and close freely can block sand and dust; their slender limbs and flat soles are also suitable for walking in the desert.

Surprisingly, the place where camels learned this magical outfit was not the vast sea of ​​sand, but the cold and barren northern grasslands. The direct ancestor of these two camels, the Paracamelus, migrated northward to escape the fierce involution of its homeland North America, and even entered the cold and desolate north of the Arctic Circle. Later, it crossed the Bering Land Bridge and became the first camel to enter the Old World, with footprints all over the three continents of Asia, Europe and Africa.

Arctic Circle Camel

Source: National Geographic

The extremely cold climate does not support the growth of tall vegetation. The camels, which originally mainly fed on leaves, once again turned their food to rough, dry grasses. They evolved increasingly developed humps, and their circulatory systems became stronger after being tempered by thousands of trials. This persistence has opened up a new world for camels.

In terms of body size, the Camelus moreli discovered in Syria is even more sturdy and taller than the Moreli camel. However, since the fossils unearthed so far are too fragmentary, it is not possible to confirm whether it is the largest camel in history.

The Moss camel is a close relative of today's dromedary and Bactrian camels.

Source: prehistoric-fauna

When camels were flourishing in the Old World, they gradually fell into dire straits in their homeland of North America. The last known member of the true camel family in North America, the western camel (Camelops hesternus), finally died out completely 13,000 years ago. North America, the birthplace of the entire family, has never seen camels since then.

Camelus pseudo-camelus

Source: CTV News

How the Internet celebrity beasts were made: the alpaca tribe

Finally, let's talk about the alpaca tribe. Compared with the camels, which are becoming more and more sturdy and rugged, the alpacas have always maintained a relatively primitive and slender shape. Today, there are only two wild alpacas in South America - guanacos and llamas. They both live deep in the mountains and have small bodies.

Four living species of alpacas

Source: https://www.inca1.com/

The most common alpaca in prehistoric America was the Hemiauchenia, which was about the same size as a small dromedary. The Hemiauchenia was a type of ancient camel with very strong adaptability. It survived from the late Miocene to the end of the Pleistocene more than 10,000 years ago. In the Early Pleistocene, it and its close relative the Palaeolama moved all the way south from the Panama Land Bridge to South America, and adapted well to the open Pampas of South America.

But the subsequent extinction event at the end of the Pleistocene eventually sent this hardy ancient camel to its grave.

Camel in South America

Source: Reddit

With the disappearance of the camelid and the ancient llama, the long-necked leaf-eating camel that once dominated the late camel evolution became completely extinct. In order to adapt to the mountainous environment of South America, the descendants of the camel, the guanaco and the vicuña, like their two distant relatives, once again turned their diet to low grasses. In a sense, this "return to the origin" is really a black joke played by nature on the camel family.

Origin and spread of Camelidae

Source: Reddit

References:

1. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 274–277.

2. A complete mitochondrial genome sequence of the wild two-humped camel (Camelus bactrianus ferus): an evolutionary history of camelidae.

3. Monophyletic origin of domestic bactrian camel (Camelus bactrianus) and its evolutionary relationship with the extant wild camel (Camelus bactrianus ferus).

4. Moore, Katherine M. (2016). "Early Domesticated Camelids in the Andes". In Capriles, Jose M.; Tripcevich, Nicholas (eds.). The Archeology of Andean Pastoralism. University of New Mexico Press.

5. Princeton Atlas of Ancient Animals

6. "Giant camel fossil found in Syria".by BBC News. 10 October 2006.

7. "Mammoths, sabertooths, and hominids: 65 million years of mammalian evolution in Europe"

Author: Xie Honghan, popular science author