A news article at Nature, "Oxygen fluctuations stalled life on Earth," is remarkable for skirting the main issue, the primary enigma.
It’s a stretch to call a tube-like burrow in the Ediacaran evidence of a bilaterian ancestor of humans.
From the earliest multicellular animals of the Cambrian explosion till today, programmed cell death has not evolved at all.
“Exactly how such convergent evolution arises is not always clear.” Is it ever?
As scientists contemplate a new fossil from China, a shrimp-like Cambrian animal with the oldest known cardiovascular system and a "thinking" brain, would you like a prediction?