Campanian and Maastrichtian plagioptychid rudists (Hippuritida, Bivalvia) of the Chiapas Central Depression, southern Mexico

Abstract

Abstract.-Plagioptychids are a conspicuous, although minor, component in uppermost Cretaceous rudist-bearing outcrops of the Caribbean Province, where other rudist families are more abundant and diverse. In the Chiapas Central Depression, the plagioptychid rudist fauna includes the following taxa: Plagioptychus antillarum (Douvillé) and Mitrocaprina sp. from the middle Campanian Suchiapa Formation, Plagioptychus muellerriedi Alencáster from the early Maastrichtian Ocozocoautla Formation, and Plagioptychus fragilis Chubb and Mitrocaprina tschoppi (Palmer) from the late Maastrichtian Angostura Formation. These five species are described in detail and some probable synonymies are discussed. Analysis of the literature on American plagioptychids reveals that the characters of too many taxa are still insufficiently known to attempt any thorough phylogenetic analysis. Other lines of evidence also seem to indicate that American Plagioptychidae diversity is probably higher than recognized today, which might result in a more significant difference to Plagioptychidae of the Mediterranean Tethys.

Mexican Upper Cretaceous rudists (Hippuritida, Bivalvia): Taxonomic, stratigraphic, and geologic data

“…Pons et al (2013) dated the two recognized rudist assemblages of the formation respectively as early and early late Maastrichtian, based on the distribution of co-occurring foraminifera (Omaña andPons, 2000, 2003;Omaña et al, 2009). Some rudist species of the Cardenas Formation were identified in the Ocozocoautla (lower Maastrichtian) or the Angostura (upper Maastrichtian) formations in Chis State (Pons et al, 2016(Pons et al, , 2017.…”

“…Also at localities SE of Tuxtla Gutiérrez, where this formation is overlain by the Angostura Formation: road to Paraíso del Grijalva 1, 2, and 3, between Laja Tendida and Paraíso del Grijalva; and road to El Santuario, SSE of San Francisco Pujiltic (Pons et al, 2016(Pons et al, , 2017(Pons et al, , 2019 (Appendix 1). Most rudist species from the first group of localities are coincident with those of the Temazcal limestones in SLP, thus early Campanian, while those from the second group are late Campanian.…”

“…Distally, the siliciclastic rocks are fine-grained and the marls contain inoceramids and ammonites. The authors collected specimens at Campo de Tiro and Los Chamaquitos, NW of Ocozocoautla; Abandoned Quarry, W of Vicente Guerrero; km 178.2, road 145 from Ocozocoautla to Las Choapas; Rancho, NW of Vicente Guerrero; and E of Emiliano Zapata (Pons et al, 2016(Pons et al, , 2017(Pons et al, , 2019 (Appendix 1).…”

Campanian and Maastrichtian hippuritid rudists (Hippuritida, Bivalvia) of the Chiapas Central Depression (southern Mexico) and implications for American multiple-fold hippuritid taxonomy

“…The Upper Cretaceous rudist fauna of Chiapas is known mainly after Alencáster (1971) and older papers by Müllerried (1931a, 1931b, 1933, 1934, 1936). More recent papers (Alencáster and Michaud, 1991; Alencáster and Pons, 1992; García-Barrera et al, 1998; Mitchell, 2013; Pons et al, 2017) added some complementary taxonomic data to the knowledge of this fauna. Pons et al (2016a) provided an inventory of rudist occurrences in the Upper Cretaceous of the Chiapas Central Depression, related their location to a lithostratigraphic framework and paleogeographic reconstruction, identified the successive rudist assemblages, and discussed their age based on the co-occurrence of other fossils (planktic and benthic foraminifers, ammonites, and inoceramid bivalves).…”

“…Pons et al (2016a) provided an inventory of rudist occurrences in the Upper Cretaceous of the Chiapas Central Depression, related their location to a lithostratigraphic framework and paleogeographic reconstruction, identified the successive rudist assemblages, and discussed their age based on the co-occurrence of other fossils (planktic and benthic foraminifers, ammonites, and inoceramid bivalves). Nevertheless, with the exception of the Plagioptychidae (Pons et al, 2017), current and detailed systematic descriptions of these rudist species remains undone.…”