The Mother of All Mammals
Posted May 1, 2002
While the dinosaurs were still thundering across the land, they were unaware of their future extinction. It was not size that would survive this event. Even the largest,
most powerful, and ferocious dinosaurs died off while the new lords of Earth emerged. They emerged from under leaves and rocks - and they were less than six inches long.
The new rulers of the world - the mammals - had humble beginnings over 100 million years ago. What would eventually become majestic elephants, tigers, bears, and even
humans began as prehistoric rodents scurrying through the brush under the feet of dinosaurs.
In the year 2000, Chinese scientists dug up a fossil of one of the earliest known mammals. This creature is comparable to the contemporary shrew and weighed less than
one pound. At only five inches long, this creature had long claws, was a good climber, and survived on a diet of insects.
The animal lived during the Cretaceous period of prehistory, which most people associate with the time that Tyrannosaurus walked Earth. This fossil is thought to be
125 million years old and was found in an area of China where many well-preserved fossils are uncovered. This specimen was so well preserved that scientists could detect hair in the
fossil.
Earlier this year, Dr. Qiang Ji of the Chinese Academy of Natural History and researchers from Pittsburgh's Carnegie Museum of Natural History elaborated on their
finding in the British scientific journal Nature.
This prehistoric shrew, named Eomaia scansoria (which means "dawn mother climber"), is the earliest known placental mammal. Only three types of mammals exist
today - marsupials that carry their undeveloped young in a pouch, monotremes which lay eggs, and placental mammals which carry their young inside them until birth. Originally there were
seven types of mammals that existed, but only the marsupials, monotremes, and placental mammals survived to modern day.
Of course, there were other animals that outlived the dinosaurs, and they were smaller than our early mammal ancestors. They are regarded as pests in our world, but
they could be the next rulers of Earth if another extinction comes along. What are they? You guessed it - the cockroach!
Activity
Use the Internet to research the origins of mammals. Make a presentation for your class that traces the possible evolutionary route of humans.
References
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