Assignment on: Paleontological History of Camel Submitted to: Anirban Sarker Assistant professor Dept. of Zoology Jagannath University, Dhaka Submitted by: Md.Imran-Al-Fahad Roll no: 117435 3rd year 1st semester 6th Batch Dept. of Zoology Date of Submission: 5th May, 2014

PALEONTOLOGICAL HISTORY OF CAMEL
Paleontology or palaeontology is the scientific study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interact- tions with each other and their environments. Paleontology lies on the boundary between biology and geology since paleontology focuses on the record of past life but its main source of evidence is fossils which are found in rocks. Paleontological history of camel denotes the evolutionary history of camel.
A camel is an even-toed ungulate within the genus Camelus, bearing dist- inctive fatty deposits known as "The humps" on its back. The two surviving species of camel are the dromedary, or one-humped camel (C.dormearius) which inhabits the Middle East and the Horn of Africa, and the bactrian, or two-humped camel(C. bactrianus)which inhabits Asia. Camels are included in family Camelidae which includes both camels and llamus, are ancient group of herbivores. Long necks, divided upper lips, and padded feet are shared characteristics of the family.

Paleontological history (evolutionary history) of camel is mentioned below briefly:-

From the late Eocene to the end of the Miocene, camels evolved and diversified exclusively in North America and have always been important components of the continent’s mega fauna.

Late Eocene (45 million years ago):

The earliest known camel was the rabbit-sized Camel (Protylopus ) . This was a forest-dweller, similar in appearance and lifestyle to modern duikers and chevrotains. It had four-toed feet with hoofed, unguligrade toes that is, they walked on the very tips of their toes. The hindlimbs were longer than the front limbs for quick acceleration and brief bursts of speed through the forest undergrowth. Lower limb bones show the beginnings of elongation and weight reduction for more efficient running, with the radius and ulna of older individuals completely fusing over time.

Early Oligocene (34 million years ago):

By Oligocene times, the dense forests of North America were giving way to more open woodland and savanna habitats, and many of the herbivores of the age were producing longer legged species able to runfaster over longer distances without expending more energy. By this time, goat-sized camels of the genus Poebrotherium made their debut. These camels had elonga- gated limbs whose lower elements had become fused to reduce the weight. The meta-carpals had elongated and fully fused into a cannon bone. The two lateral toes had been lost, making the foot fully didactyl (two-toed).The digits were showing signs of diverging into the splayed feet of later camels. Most notably, the teeth of this animal were more high-crowned than their forest ancestors, probably for incorporating more wood and ground-level vegetation. The dentition was still complete, but the incisors were starting to become more widely spaced thus lengthening the face and increasing the animal's reach.

Early Miocene (23 million years ago):

The further expansion of dry open grass-lands in the latest Oligocene and the early Miocene was met with an explosion in camel diversity. New spe- cies evolved to exploit these open conditions with three distinct lineages. First lineage was a group of gazelle-like camels of the genus Stenomylus. These evolved into small, fleetfooted grazing animals with enlarged molars to deal with abrasive grasses and forbs. The gazelle camel lineage was rather short-lived, becoming extinct with the emergence of the pronghorns during the middle Miocene. Second lineage was a group of long legged, longnecked camels that appear to have specialized to browse high ground level. The giraffe-camels of the genera Oxydactylus and Aepycamelus retained complete dentition with same low-crowned teeth of its ancestors.
The third lineage continued up the line of descent toward modern camels with the genus Procamelus. In this genus, the first two upper incisors are absent, replaced by a tough pad that works together with the lower incisors. The rostrum is elongated with widely-spaced conical third upper incisors, canines and first premolars. These features were inherited by all later camels, including the extant species, and Procamelus itself would have looked very much like a living Guanaco.

Cenozoic Era (Age of mammals) |

Recent | Dromedary or Arabian camel | Bactrian camel | Lama glama | Lama guanicoe | Vicugna vicugna | Vicugna pacos (Alpaco) | Holocene | Camelus | Lama | Vicugna | Pleistocene | Camelops groups developed | Hemiauchenia developed | Llama developed & extinct | Pliocene | Titanotylopus nebraskensis | Late Miocene | Camelops | Hemiauchenia | Llama | Extinct | Early Miocene | Procamelus | Oxydactylus | Sternomylus | Aepycamelus | Oligocene | Poebrotherium | Eocene | Protylopus |

Table: Evolutionary history of camel

Late Miocene (5.8 million years ago):

At the end of the Miocene about 5.8mya, Procamelus became the first camel to enter Eurasia. Since then, camels have made tentative incursions into the Old World but never attained diversity they had achieved in North America because of the competition they now faced from the various species of deer, antelopes, and giraffes in this new land. The two species that currently inhabit the Old Worldare specialized for life in arid steppe and desert habitats and their efficient energy and water conserving physiologies gave them an adaptive advantage over ruminants environments. Back in North America at this time, the Giraffe Camel (Aepycamelus major) was the last surviving member of the giraffe camel lineage. Procamelus persisted here as well, but by now it had given rise to two sub lineages of camels; the llamas (represented by Pliauchenia/Hemiauchenia) and the humped camels (representedby Camelops).

Pliocene (3.5 milliom years ago):

During the Pliocene around 3.5mya, the Giant Camel (Titanotylopus nebraskensis) evolved in North America. This was a Giraffe sized browser adapted for feeding on high foliage. In the early Pleistocene this species would spread into Eurasia where it reached as far west as Ukraine, but does not appear to have entered Africa,perhaps due to the presence of the Giraffe on that continent. Camels nonetheless did appear briefly in Africa during the The Giant Camel (Titanotylopus neb raskensis), a Giraffe-sized browser that survived from the Pliocene to the late Pleistocene .

Late Pleistocene ( 20,000years ago):

During the late Pleistocene there were at least 8 species of camel alive in
North America, most of which having South American distributions. The
Giant Camel remained abundant and had spread throughout the Northern
Hemisphere by this time, reaching as far east as Ukraine. The humped Camelops persisted and was represented by 3 species; the Western
Camel(C. hesternus), the Kansas Camel (C.kansanus), and the Huerfano
Camel (C.huerfanensis).The Stoutlegged Llama(Palaeolama mirifica) lived throughout southern North America through to South America.

The genus Hemiachenia, which evolved in North America during the late Miocene, had diversified and spread through South America where it gave rise to two extant species. The Blanco Llama (H. blancoensis) was widely distributed, inhabiting most of North America and reaching southern South
America by 1.5mya. The Large-headed Llama (H. macrocephala) was slightly smaller than the Blanco The Western Camel (Camelops hesternus) was among the most common camel species in North America during the
Pleistocene. Llama, standing about 2m tall at shoulder with long, Robust limbs. This llama was a grazer with a broad mandibular symphasis, fully molariform second upper premolar, and hypsodont cheek teeth with a thick layer of cementum. Sediments where it was found indeed show that it inhabited open grasslands. The True Llama (H. vera) lived in the western United States and northern Mexico. It was a browser with relatively low-crowned teeth. All these camels persisted until the end of the Pleistocene about 13,000 years ago.

Holocene 10,000 years ago to Recent:

A major ecological disturbance at the end of the Pleistocene wiped out camels from North American continent, leaving behind four species still alive today; two in South America and two in Asia and Africa. In South America the descendants of Hemiauchenia persisted as the genus Lama, which appeared during the late Pliocene about 3 million years ago. The living Guanaco(L.guanicoe) and the Vicuna (L.glama) are both mountain-adapted grazers that fill the same niches that mountain sheep occupy else where in the world. In Old World,two species of the genus Camelus survive to present day having descended from Camelops that crossed Beringia in the early Pleistocene; the Bactrian Camel (C. bactrianus) and the Dromedary Camel (C. dromidarius). These animals are adapted to life in deserts and arid grasslands. The Dromedary is currently more numerous of the two, abundant throughout northern Africa and southern Asia, and having a rather large feral population in Australia. The two humped
Bactrian is not faring as well as its one-humped cousin. Over 2 million now survive in captivity, but the species is highly endangered in the wild.

Fig. The four surviving camels; Dromedary Camel (above left), Bactrian Camel (above right),Vicugna (bottom left), and Guanaco (bottom right).