card
041

Deltatheridium

OLogy Series
specimen
card
041

Deltatheridium

OLogy Series
specimen

Flashback to 80 million years ago in the Gobi Desert. Deltatheridium scurried among dinosaurs. This cat-sized mammal had sharp canine teeth and triangular molars, much like those of opossums today. This early marsupial probably sunk its teeth into small lizards and insects.

So, What Are Ya, Marsupial or Placental?
Since the discovery of Deltatheridium, scientists knew that it was an early mammal. However, before the late 1990s, they debated about what kind of mammal it was. Was it a marsupial (pouched mammal such as opossums and kangaroos) or a placental (a mammal that gives birth to fully developed young, such as rats, bats, and whales)? Now, thanks to some amazing fossil evidence from the Gobi, scientists have the answer. On the mammal family tree, Deltatheridium is definitely a marsupial. Although Deltatheridium's descendants went extinct, some of its "cousins" became the marsupials we know today.

Deltatheridium is probably a relative to which modern animal?

kangaroo

pig

parakeet

Are you right?

Correct!

Scientists believe that Deltatheridium had characteristics that are very similar to marsupials (pouched animals) that live today.

We found Deltatheridium -- this beautiful, little skull -- at our favorite site, Ukhaa Tolgod.

Many more mammal species have lived and gone extinct than are alive today.

Fact
or
Fiction
?

Fact

Mammals in the world today make up only a tiny part of all of the mammal species that have ever existed.

Although many kinds of mammals lived in North America during the Cretaceous, most of their fossils were destroyed.

Fact
or
Fiction
?

Fact

Early mammal fossils from North America are no more than teeth and partial jaws. But in the Gobi, entire mammal skeletons are commonly found.

Deltatheridium prerituberculare
(del-tah-ther-ID-ee-um)
Locality Found: Mongolia
Age: Cretaceous 80 MYA Size: 6 inches long
Prepared For: 2000 Museum exhibit Fighting Dinosaurs
Characteristics: Paleontologists believe that Deltatheridium was an early ancestor to modern day marsupials.

Image credits: courtesy of AMNH; Mark Norell: courtesy of Discovery Channel Online.