Figure 9. Successive pre-Aptian reconstructions of Gondwana and North America, using the Equatorial Atlantic fit of Figure 8. This analysis provides a quantitative framework in which to build more locally detailed models of the evolution of the Gulf of Mexico and surrounding areas. Note pre-Andean/pre-rift restoration of the northern Andes on the Triassic position of South America: This defines how much of Mexico is definitely allochthonous versus how much is potentially -- but not necessarily -- autochthonous.