Eldredge, Niles American Museum of Natural History, New York, New York.
- Related Primary Literature
- Additional Reading
Living species very closely resembling fossil relatives in most anatomical details. The term is a relative one and, applied loosely, could embrace nearly all extant animals and plants. In its more restricted usage, the term applies to living species with four additional characteristics: (1) truly close anatomical similarity to (2) an ancient fossil species—generally at least 1 × 108 years old; (3) living members of the group are represented by only a single or at best a few species, which are (4) often found in a very limited geographic area. Examples are horseshoe crabs (found on the eastern shores of the two Northern Hemisphere continental landmasses, with closely similar relatives over 2 × 108 years old); ginkgo trees, dating from the Mesozoic era, which, until their recent introduction over the world, were restricted to Asia; and coelacanth fish, which have not changed much since the Devonian and which today are found only between eastern Africa and Madagascar and the Comoro Islands.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information