Not actually presented as a timeline (despite the appearance of my images above), but as a slide show, it steps through some significant titles and artists in the course of the presentation. The images are somewhat small, but large enough to get a feeling for the art and, along with the text describing the books, let you follow up by digging further elsewhere.
There are other resources on the site, but I found most of them less than compelling. The “Artistic Media” and “Artistic Style” sections near the bottom of the navigation include some more book covers and work by various artists. The “Artists and Authors” section, probably the most useful of them, is a list that includes links to the creators’ websites.
(Artists above, links are to my posts: Johannes Amos Comenius, Kate Greenaway, Howard Pyle, John Tenniel, Arthur Rackham, Maxfield Parrish, W.W. Denslow, Crokett Johnson, Maurice Sendak, Chris van Allsbugh, Brian Selznick)