Fossil record of Upper Paleozoic Marine Invertebrates from Mexico.

Upper Paleozoic fossil invertebrates of Mexico represent communities of marine environments associated with continental margins. A high percentage of very diverse brachiopods and mollusks, accompanied by other lesser diverse groups such as echinoderms, arthropods, bryozoans and corals occur throughout the Upper Paleozoic sequence of Mexico. Outcrops of Carboniferous and Permian rocks are especially abundant and Mexican fossil faunas from those systems exhibit an affinity to similar age fossil faunas from the rest of North America; this is especially true in the youngest faunas. This similarity may be explained by the configuration and geographic position of the Late Paleozoic crustal portions that form modern day Mexico. During the Late Paleozoic Pangea was forming and the ocean that existed between Gondwana and the northern continents was narrowing: during the entire Carboniferous and Early-Middle Permian, that ocean covered large regions of North America and extended over the majority of what constitutes present-day Mexico. [ABSTRACT FROM AUTHOR]