The content you've requested is available without charge only to active Sigma Xi members and American Scientist subscribers.
If you are an active member or an individual subscriber, please log in now in order to access this article.
If you are not a member or individual subscriber, you can:
The evolution of jaws was a crucial step in vertebrate history, but
it took place so long ago that fossils from this period consist
mostly of teeth and a bewildering variety of skin scales. Now an
almost complete shark fossil gives paleontologists the opportunity
to investigate the poorly understood transition between sharks and
modern fishes and to interpret isolated fossils from a new
perspective. The remarkably intact 409 million year-old example
preserves the braincase, jaws, teeth and pectoral fins in the
correct anatomical position. Based on this finding, the authors
revise the geography of early shark evolution and question the
accepted picture of shark evolution as it relates to other major
Connect With Us:
An early peek at each new issue, with descriptions of feature articles, columns, and more. Every other issue contains links to everything in the latest issue's table of contents.News of book reviews published in American Scientist and around the web, as well as other noteworthy happenings in the world of science books.
To sign up for automatic emails of the American Scientist Update and Scientists' Nightstand issues, create an online profile, then sign up in the My AmSci area.
JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.
The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.
View the full collection here.
Receive notification when new content is posted from the entire website, or choose from the customized feeds available.