The nadir of the sun is the axis of the shadow projected by the Earth.

The emergence of new, more efficient means of predation and foraging - 'terrors with teeth' with a through-gut (an early, small version of the 'tube' which Steve Jones reminds us we all are) connected to the anus, which could process what they ate with more efficiency than any previous animal.

And receive into thy heart the instructions that I shall give thee now, and see that thou swerve not from them, nor abatest them a jot; for if thou observest them not, or departest in aught from them, thou wilt bring damnation upon thy soul; […]

[…] whosoever thou art that judgest: for wherein thou judgest another, thou condemnest thyself; for thou that judgest doest the same things.