- As the environment became drier and hotter, reptiles thrived at the expense of amphibians. Figure 06 shows many types of the reptiles living way up in the mountain. They are representatives of the groups of pelycosauria, "mammalian" reptiles from which the evolutionary line to the first mammals can be traced. They shared with mammals a particular type of skull. A single large opening in the wall of the skull behind the eye socket allowed highly efficient jaw-closing muscles to develop, greatly increasing the power of the jaws. The huge dorsal fan may have acted as temperature regulator. The amphibians with the tapering head were evidently the prey of the reptiles.
- Mass extinction of marine life near the end of the Permian period - Groups made extinct include trilobites, sea lilies, and rugose corals. Other marine invertebrates severely affected. Fish are generally unaffected. According to recent investigation, the disaster that killed off almost 90% of all life on Earth about 251 MYA, was likely caused by a huge asteroid or comet crashing into the planet.
