GEOLOGIC RECORD OF CAMELS

Camels are artiodactyl (even-toed) mammals belonging to family Camlidae. Some other examples of artiodactyls are giraffes, deer, buffalo, cows, pigs, and even whales!

The oldest known camel is Protylopus. It is of approximately middle Eocene age (40 to 50 m.y.a. [million years ago]), and it lived in what is now South Dakota. This camel was 4 feet tall, 2.6 ft. long, and weighed 57 pounds). It lived in open woodlands and fed on soft leaves. Its front legs were shorter than its hind legs, and its feet were four-toed.

Protylopus, the earliest known camel. Sketch by author and based on image in animaladay.blogspot.com

During the latest Eocene/earliest Oligocene in western U.S.A., two other camel genera evolved in North America: Poebrotherium and  Stenomylus, both of which started to look more like modern camels.

Poebrotherium. Sketch by author based on image in ideas.fandom.

com/wiki

Stenomylus. Sketch by author based on image in Wikipedia. This camel walked "tip-toed," like a modern gazelle.

Aepyecamelus is of late Miocene age. Sketch by author based on image in Wikipedia.org Aepycamelus lived when there was increased cooling going on, and the dry savannah was replaced by steppe lands. 

Note: Other camelid genera that lived during the Miocene were Alticamelus, which was 19 feet tall, and Ocydatylus, which had a neck as long as a giraffe. 

Paracamelus migrated from North American to Eurasia via Beringia #2 (see one of my previous posts about Beringia = a land bridge between North America and Asia. This camel was the first to enter the North American arctic region. During the time of Paracmelus, which was latest Miocene through early Pleistocene, camels grew larger (up to 9 feet (2.7 m tall), with longer necks. Their teeth got longer and had higher crowns than before. Also, their feet obtained pads. Sketch by author based on image in Wikipedia.

Paracamelus also migrated into South America during Pliocene/Pleistocene = GABI time (see one of my previous posts about GABI = the Great American Biotic Interchange. In South America, Paracamelus evolved into llamas, alpaca, guanacos, and vicuñas.

Camelops hesternus, which was native to North America, was the last camelid to live during the late Pleistocene [13,000 to 11,000 years] in North America. The remains of this extinct camelid have also been found in the La Brea Tar Pits in Los Angeles, California. Sketch by author based on image in Wikipedia. According to Heintzman et al. (2015), Camelops is a “sister group” to African and Asian Bactrian and dromedary camels but not similar to South American camelids.

Modern-day camelids are represented by three species: 1) Camelus dromodarius [the dromedary camel-- has one hump], 2) Camelus bactriannus [the Bactrain camel (has two humps), and 3) Camelus ferus [the “wild” Bactrain camel (also has two humps). 

The humps are used to stored fat.

The dromedary camel Camelus dromodarius, also known as the “Arabian camel,” lives in the Middle East, Sahara Desert, and south Asia. This camel is the smallest in size (6 feet high and usually about 600 pounds) of the three living species of camels. Sketch by author is based on image from Wikipedia.

Two specimens Camelus dromodarius at the “Living Desert Zoo and Gardens,” in Palm Desert, Riverside County, southern California [December, 2023]. Image courtesy of C. S.

The Bactrain camel, which is also known as the “Mongolian camel,” lives in central Asia. This camel can be up 1200 pounds. Sketch by author is based on image from Wikipedia.

The “wild” Bactain camel lives in China and southwestern Mongolia. This camel is critically endangered. Sketch by author is based on image from Wikipedia.

References Consulted:

Heintzman, P.D. and five others. 2015. Genomic data from extinct North American Camelops revise camel evolutionary history. Molecular Biology and Evolution 32(9):pp. 2433–2440. (free pdf)

en.Wikipedia.org