## Problem 308 — rank:200

**Title:** Causes and tempo of the Cambrian radiation

**Added binding assumptions (LaTeX):**

```latex
Provide a character-evolution and sampling model for morphological disparity as well as the lineage birth--death model; richness dynamics alone do not generate the disparity statistic. Specify temporal direction, dating uncertainties and formation-level dependence consistently. Rate-covariate coefficients are causal only under a justified structural model. Fossil recovery and lineage diversification must be jointly constrained before a rapid observed accumulation is attributed to a biological radiation.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.