Major Radiations in the Evolution of Caviid Rodents: Reconciling Fossils, Ghost Lineages, and Relaxed Molecular Clocks
Figure 6
Diversification plot of cumulative number of cavioid lineages (leading to both extinct and extant species) against geological time.
The red curve represents the number of lineages based on the simultaneous analysis of morphological and molecular data of both extinct and extant taxa (as shown in Fig. 4). The uncertainty in the geological age of each fossil creates a maximum and minimum times of divergence and is represented by the breadth of the diversification events on the red curve. The blue line represents the timing of diversification events of crown caviid lineages based on mean age estimates of the molecular clock estimates. The most relevant SALMAs are highlighted and the numbers 1, 2, 3a, and 3b represents the Deseadan radiation (1), the Santacrucian radiation (2), the initial diversification of Caviidae (3a), and the diversification of modern and morphologically well differentiated lineages of caviids during the Chasicoan (3b). The black arrow marks the discrepancy between the timing of the initial diversification of Caviidae based on the paleontological record (red curve) and the molecular clock estimates (blue curve).