Scientists have unearthed fossil teeth and a jaw fragment in Oregon. And these have helped flesh out the features of an ancient animal that once lived in North America. A new species of primate, it had features similar to a modern lemur’s.
Primates are a group of mammals that includes monkeys, lemurs, gorillas and humans. The Sioux are a tribe of Native Americans. The newfound primate’s genus name comes from a Sioux term for monkey: Ekgmowechashala. It’s pronounced something like IGG-uh-mu-WEE-chah-shah-lah. These last nonhuman primates to live in North America vanished around 26 million years ago. No other primates lived in North America until humans arrived well over 25 million years later. This timeline comes from the new study. It was published June 29 in the American Journal of Physical Anthropology.
All came from rocky sediment at Oregon’s John Day Formation. This rock layer, or stratum, contains fossils from between 30 million and 18 million years ago. A tooth and jaw fragment from the same species had been found there previously. All the fossils belong to a new species of Ekgmowechashala, the researchers say. Partial jaws and teeth of a related species had turned up at sites in South Dakota and Nebraska.
The scientists figured out the age of the fossils based on their position between layers of volcanic ash. The ages of those layers was already known. That let the scientists determine that the new fossils must be between 28.7 million and 27.9 million years old.
Where did the primates come from?
Millions of years ago, land connected what is now Alaska and Russia. The ancient primates probably crossed that “land bridge” around 29 million years ago, the researchers now say. That journey would have taken place some 6 million years after other North American primates had died out.
Samuels says the new fossils appear to resemble those from a 34-million-year-old primate from Thailand, in Southeast Asia. The new fossils also are similar to a 32-million-year-old primate from Pakistan, which lies between the Middle East and India.
Erik Seiffert is a paleontologist at Stony Brook University in New York. He suggested an Asian–North American primate connection back in 2007. But Samuels and his team “have laid out the evidence in more detail,” Seiffert now says.
Some researchers suspect Ekgmowechashala’s closest present-day relatives would have been tarsiers. These small primates live on islands in Southeast Asia. Other scientists think the now extinct North American primates were more closely related to lemurs. They exist only in Madagascar. It’s an island off of the East Coast of southern Africa.
K. Christopher Beard agrees with Samuels’ team that Ekgmowechashala is likely more related to the lemurs. A paleontologist, Beard works at the University of Kansas in Lawrence. But he argues that to confirm this, scientists need to find ankle bones. They should point out whether the ancient primate species had a greater kinship to lemurs or to tarsiers.
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ash (in geology) Small, lightweight fragments of rock and glass spewed by volcanic eruptions.
epoch (in geology) A span of time in the geologic past that was shorter than a period (which is itself, part of some era) and marked when some dramatic changes occurred.
fossil Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.
genus (plural: genera) A group of closely related species. For example, the genus Canis — which is Latin for “dog” — includes all domestic breeds of dog and their closest wild relatives, including wolves, coyotes, jackals and dingoes.
land bridge A narrow region of land linking two large masses of land. In prehistoric times, a major land bridge connected Asia and North America across the Bering Strait. Scientists believe early humans and other animals used it to migrate between the continents.
lemur A primate species that tends to have a cat-shaped body and usually a long tail. They evolved in Africa long ago, then migrated to what is now Madagascar, before this island became separated from the east coast of Africa. Today, all wild lemurs (some 33 species of them) live only on the island of Madagascar.
Native Americans Tribal peoples that settled North America. In the United States, they are also known as Indians. In Canada they tend to be referred to as First Nations.
Oligocene epoch A span of time in the distant geologic past that ran from 33.9 milllion to 23 million years ago. It falls in the middle of the Tertiary period. It was a cooling period on Earth and was a time when a number of new species emerged, including horses, elephants with trunks and grasses.
paleontologist A scientist who specializes in studying fossils, the remains of ancient organisms.
primate The order of mammals that includes humans, apes, monkeys and related animals (such as tarsiers, the Daubentonia and other lemurs).
species A group of similar organisms capable of producing offspring that can survive and reproduce.
strata (singular: stratum) Layers, usually of rock or earthen materials, whose structure tends to vary little. It is usually different from layers above and was produced at a different period of time using different ingredients.
volcano A place on Earth’s crust that opens, allowing magma and gases to spew out from underground reservoirs of molten material. The magma rises through a system of pipes or channels, sometimes spending time in chambers where it bubbles with gas and undergoes chemical transformations. This plumbing system can become more complex over time. This can result in a change, over time, to the chemical composition of the lava as well. The surface around a volcano’s opening can grow into a mound or cone shape as successive eruptions send more lava onto the surface, where it cools into hard rock.