1. Impressive invertebrates
Fifty-eight million years ago…
China’s Qingjiang biota is a treasure trove of perfectly preserved fossils, including jellyfish (left),comb jellies (middle), mud dragons (right) and arthropods.
The fossils document the Cambrian explosion, a rapid flourishing of life-forms, and include many organisms that have never been seen before, even at Canada’s most famous fossil site, Burgess Shale.
2. Tetrapod walking
290 million to 280 million years ago
Using re-created skeletons, fossil trackways, computer simulations and a robot (shown), scientists concluded that four-foot Orobates pabsti kept its belly off the ground as it moved with minimal side-to-side undulation.
For such an ancient criterion, O. Pabsti, one of the earliest amniots, a group of reptiles and mammals, had an surprisingly and exceptionally efficient gait.
3. Oldest bone cancer
240 million years ago
A growth preserved in an ancient turtle relative’s fossilized left femur is the oldest known case of amniote bone cancer [bracket reveals the tumor on the multi-centimeter-long fossil].
4. A bone for chewing
165 million years ago
A shrew-sized mammal relative, Microdocodon gracilis (illustrated), had a flexible bone called the hyoid connected to the jaw millions of years before true mammals emerged. The hyoid allows and helps mammals to chew, swallow and suck, a key innovation that can be a secret to the success of mammals.
5. Unlaid egg
110 million years ago
A small bird died still inside her body with an egg [arrow], and difficulties with laying the egg might have led to her death. Broken and flattened over time by pressure. The specimen is the first unlaid bird egg discovered preserved as a fossil.