Calling all users of PBS LearningMedia/Teachers' Domain materials!
WGBH is trying to develop materials that better meet the needs of our users. Please take this brief survey to share how you use these resources and to provide feedback on your experiences using these materials. Take the Survey!
This graphic illustrates some of the marsupial mammals in Australia and placental mammals in North America. Even though they are not closely related, these mammals look alike because they have adapted to similar ecological roles.
Marsupial and placental mammals diverged from a common ancestor more than 100 million years ago, and have evolved independently ever since. The two groups have different modes of reproduction, yet within each group individual species that occupy similar niches have evolved similarities in overall shape, locomotion, and feeding habits. This widespread evolutionary phenomenon is known as convergence.
Discuss how the geological history of land masses in the northern and southern hemispheres, combined with the timing of early events in mammalian evolution, led to the separation of ancient marsupial and placental mammals.
Discuss the concepts of adaptive radiation and convergent evolution, and how they relate to one another in explaining the evolution of the separate, yet parallel, marsupial and placental faunas found today in Australia and North America.
South America was historically home to many more marsupial species (along with some other odd, extinct mammals) than live there today. Discuss how continental drift and competition explain this current situation.
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.
Download Only
Loading Standards
Teachers' Domain is proud to be a Pathways portal to the National Science Digital Library.
Background Essay
Print Background Essay