Click on the image to read an article about the discovery of a complete, unbroken sequence of "forams". The sequence is 66 million years long, and includes about 330 species.
A "foram" is a single-celled ocean plankton, either free-floating or else bottom dwelling. In the image, "ma" means "millions of years ago". So, the image shows a sequence from 64.5 million years ago, to 58 million years ago.
The overall sequence is so enormous because the tiny fossils can fit between grains of sand, and escape being crushed. The sequence was very hard to study until recently, when a computerized system was developed. It can identify and classify forams, and it is connected to a microscope.
Here is a second article about the same discovery.
NOTE: Unfortunately, Florida State has lost the original articles from its computers. However, they have given me permission to use my personal copies.