First record of Halysites catenularius (Cnidaria-Tabulata) from the Silurian of Rancho Placeritos, Central Sonora, Mexico: Paleoecological and paleogeographical considerations

Halysites catenularius Linnaeus is reported from the Silurian strata that form outcrop in the Rancho Placeritos (San Antonio dolostone) located west of Hermosillo, capital of Sonora, Mexico. In this region, a sequence of Paleozoic sedimentary rocks of ages ranging from the Upper Ordovician to the Lower Mississippian is exposed. Halysites catenularius is identified as a reef buildings tabulate coral associated with calcareous algae, sponges, rugose corals, other tabulate corals, bryozoans, brachiopods and, pelmatozoans. The biota developed in shallow tropical seas from southwest of the North American craton, which was located near the paleoecuatorial line. The Silurian platform deposits of Sonora correlate with localities in the southern United States of America and northern Mexico (Sonora and Chihuahua) that were part of the margin of the North American craton. The description of Halysites catenularius contributes to the knowledge of the biota of the lower Paleozoic of Mexico, particularly the Silurian.