Iron-Phosphorus Coupling as the Thermodynamic Bottleneck of Complex Life: From Stellar Nucleosynthesis to the Cambrian Explosion

The Cambrian Explosion required not only oxygen but also the simultaneous availability of bioavailable iron and phosphorus. This paper proposes that schreibersite (Fe33P), delivered by the Tiamat disruption event, provided the coupled Fe-P source. A six-step energy cascade from supernova nucleosynthesis to mitochondrial ATP synthesis is presented. The 4.5 Gyr delay is explained by geochemical locks: magma ocean, BIF precipitation, and Snowball Earth redistribution. Predictions include diagnostic Fe-P minerals in Archean rocks, a Fe/P spike in pre-Cambrian phosphorites, phosphate in Europa's ocean, and a galactic phosphorus gradient constraining SETI targets. This is Paper 4 of the Tiamat Hypothesis Series.