The Island of Shrinking Mammoths How the Chalicothere Split In Two 2 weeks ago   12:15

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The mammoths fossils found on the Channel Islands off the coast of southern California are much smaller than their relatives found on the mainland. They were so small that they came to be seen as their own species. How did they get there? And why were they so small?

Thanks to Ceri Thomas for the mammoth reconstructions throughout this episode. Check out more of Ceri's paleoart at and

Thanks to Julio Lacerda and Studio 252mya for the Palaeoloxodon illustrations. You can find more of Julio's work here:

Produced in collaboration with PBS Digital Studios:

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“Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals.” Niimura Y, Matsui A, Touhara K. 2014.
Evolution of Island Mammals: Adaptation and Extinction of Placental Mammals on Islands by Alexandra van der Geer, George Lyras, John de Vos and Michael Dermitzakis.
Niimura Y, Matsui A, Touhara K. 2014. Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals. Genome Res doi: 10.1101/gr.169532.113
"Sea level, paleogeography, and archeology on California's Northern
Channel Islands," by Reeder-Myers et al. 2015.

Comments 1059 Comments

Jackson Porter
Great to see the Channel Islands talked about by one of my favorite channels
Demi Ajomale
When is the new video
Sang Eeth
So this is how King King got so huge. Intredasting.
Lily Wang
Puppy sized elephants, we are getting there.
Daniel Snyder
They couldn't have seen it - mammoths are known to have had poor distance vision.
Kristof Wynants
Maybe they were curious... or bored... or they swam there just because they could. Elephants are known to be highly inquisitive so...
8:25 like Pod's Travels from Dinosaur Planet, where Pod ends up on an island with dwarf versions of himself.
This is mentioned in the documentary miniseries Dinosaur Planet (2003) when Scott Sampson mentions a species of mammoth shrinking on an island while he's talking about dwarf dinosaurs.
Speaking of giant birds, why have theropods shrunk?
Hey guys, let me throw in some suggestions for the next animal evolution videos:
1. How and why did the order Carnivora (which includes most mammalian predators) split into two basic lineages - Caniformia (dog-like creatures) and Feliformia (cat-like creatures), and why the former seem to be more diverse and numerous than the latter.
2. How it came to be that all bears except the polar one tend to eat more plants/invertebrates than full-blown vertebrate meat, the prime example being the giant panda. As opposed to other large land predators, like big cats for example.
3. The evolution of fur on mammal-like reptiles and mammals as opposed to feathers on dinosaurs.
4. The evolution of animal psychology as brain size grew.
Guilherme Tonon
they didn't need less suply, they hadn't. So the next generation grows week and smaller, and thinner.
So... it´s not like they had less food.
A. G.
I would like to have that small mammut at home )
He should eat not very much, not more then horse.
Mike Dennis
These animals were also found on Wrangel Island near Siberia.
I've been following this since the beginning, and I have to say, even if each video is really, really good, I need to also compliment the music used, it's so nice!! I always find myself paying attention to the music when I rewatch because it's so good. Such a good soundtrack.
Did you know it happened to dinosaurs as well.

There was at one point a group of sauropod dinosaurs that lived of a group of islands and they were predated by a pterosaur.
The mammoth smelling with its trunk is cute.
Matan Alayof
Hi at 3:10 you show iceberg that require water and the sea level drops but its only land ice the its freezing drops the see level
Kavin Kumar
I would like to know if how were different dinosaur parents.
wow i never would have thought the scene from tarzan where the elephant swims and uses his trunk like a snorkel would be accurate. but the trunk probably cant double as a periscope, i'm guessing.
Harsh Mangal
Of course, it had to be us!
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How the Chalicothere Split In Two The Island of Shrinking Mammoths 2 weeks ago   07:58

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Two extinct relatives of horses and rhinos are closely related to each other but have strikingly different body plans. How did two of the same kind of animal, living in the same place, end up looking so different?

Thanks to Ceri Thomas for the very cool Anisodon reconstruction. Check out more of Ceri's paleoart at and
And thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart:
Finally, thanks to Dmitry Bogdanov, Roman Uchytel, Ryan Somma and Julio Lacerda for their excellent images as well.

Produced in collaboration with PBS Digital Studios:

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Prothero, D. R., & Schoch, R. M. (1989). The evolution of perissodactyls (Vol. 15). Oxford University Press, USA.
Peters, N., & de Vos, J. (2012). First evidence of a chalicothere (Mammalia, Perissodactyla) in The Netherlands. Cainozoic research, 9(2), 141-144.
Clauss, M., Frey, R., Kiefer, B., Lechner-Doll, M., Loehlein, W., Polster, C., ... & Streich, W. J. (2003). The maximum attainable body size of herbivorous mammals: morphophysiological constraints on foregut, and adaptations of hindgut fermenters. Oecologia, 136(1), 14-27.
Heaney, L. R. (1991). A synopsis of climatic and vegetational change in Southeast Asia. In Tropical Forests and Climate (pp. 53-61). Springer, Dordrecht.
Churcher, C. S. (2014). A vacant niche? The curious distributions of African Perissodactyla. Transactions of the Royal Society of South Africa, 69(1), 1-8.
Werdelin, L., & Sanders, W. J. (2010). Cenozoic mammals of Africa. Univ of California Press.
Colbert, H. (1935). Distributional and phylogenetic studies on Indian fossil mammals. III. A classification of the Chalicotherioidea. In American Museum Novitates.
Bai, B., Wang, Y., & Meng, J. (2011). Early Eocene chalicothere Litolophus with hoof-like unguals. Journal of Vertebrate Paleontology, 31(6), 1387-1391.
Peterson, O. A. (1907). Preliminary notes on some American chalicotheres. The American Naturalist, 41(492), 733-752.
Munthe, J., & Coombs, M. C. (1979). Miocene dome-skulled chalicotheres (Mammalia, Perissodactyla) from the western United States: a preliminary discussion of a bizarre structure. Journal of Paleontology, 77-91.
Janis, C. M., Scott, K. M., & Jacobs, L. L. (Eds.). (1998). Evolution of tertiary mammals of North America: Volume 1, terrestrial carnivores, ungulates, and ungulate like mammals (Vol. 1). Cambridge University Press.
Coombs, M. C., & Rothschild, B. M. (1999). Phalangeal fusion in schizotheriine chalicotheres (Mammalia, Perissodactyla). Journal of Paleontology, 73(4), 682-690.
Coombs, M. C., Hunt Jr, R. M., Stepleton, E., ALBRIGHT III, L. B., & Fremd, T. J. (2001). Stratigraphy, chronology, biogeography, and taxonomy of early Miocene small chalicotheres in North America. Journal of Vertebrate Paleontology, 21(3), 607-620.
Coombs, M. C. (1979). Tylocephalonyx, a new genus of North American dome-skulled chalicotheres (Mammalia, Perissodactyla). Bulletin of the AMNH; v. 164, article 1.
Coombs, M. C. (1975). Sexual dimorphism in chalicotheres (Mammalia, Perissodactyla). Systematic Biology, 24(1), 55-62.
Semprebon, G. M., Sise, P. J., & Coombs, M. C. (2011). Potential bark and fruit browsing as revealed by stereomicrowear analysis of the peculiar clawed herbivores known as chalicotheres (Perissodactyla, Chalicotherioidea). Journal of Mammalian Evolution, 18(1), 33-55.
Zapfe, H. 1976. "Die Fauna der miozanen Spaltenfiillung von Neudorf a. d. March (CSSR). Chalicotherium grande (Blv.)." Sitzungsberichte Osterreich Akad. Wissenschaften, Math.-na-turwiss. Klasse (Abt. I) 185: 91-112.
Zapf 1979. "Chalicotherium grande (Blainv.) aus der miozanen Spaltenfiillung von Neudorf an der March (Devinska Nova Ves), Tschechoslowakei." Neue Denkschriften Naturhist. Mus. Wien 2: 1-282. Zhou, Mingzhun, Yu
Munthe, J., & Coombs, M. C. (1979). Miocene dome-skulled chalicotheres (Mammalia, Perissodactyla) from the western United States: a preliminary discussion of a bizarre structure. Journal of Paleontology, 77-91.
Wunderlich, R. E., and W. L. Jungers. "Manual digital pressures during knuckle-walking in chimpanzees (Pan troglodytes)." American journal of physical anthropology 139.3 (2009): 394-403.