Quantitative paleoecology of Cambrian (Series 2–Miaolingian) communities from central Sonora, Mexico

Héctor Arturo Noriega-Ruiz, Francisco Javier Cuen-Romero*, Luis Fernando Enríquez-Ocaña, Rogelio Monreal, Elizabeth Chacón-Baca, Juan José Palafox-Reyes, Francisco Javier Grijalva-Noriega

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This work presents a paleoecological approach to study benthic communities preserved in Cambrian strata exposed at the Sahuaral locality in central Sonora, northwestern Mexico. Based on species richness and abundance, this work analyzed 627 individuals corresponding to 33 species from five distinctive Cambrian formations: the lowermost Proveedora Formation characterized by bioturbation horizons that record the occurrence of a benthic-infaunal biota from coastal shallow seas, followed by the Buelna Formation which contains reef deposits dominated by autotrophic epibenthic communities. The Cerro Prieto Formation was deposited in a high-energy shallow marine environment, dominated by primary consumers-epifaunal and suspensions feeders. The uppermost unit, the El Gavilán Formation, is an intercalation of shale and fossiliferous limestone characterized by the fossil remains of suspension feeders, detritus feeders and nektobenthic organisms of low energy deep water environments. The paleobiota consist of ichnofossils, microbial oncolites, chancellorids, brachiopods, hyolithids, and trilobites in a sequence of increasing diversity and complexity. Paleoecological indices (Simpson Dominance, Shannon-Weaver Index, Evenness Index, and Total Richness) were determined and compared in the study area. In addition, the effective number of species and the true diversities were obtained, which are similar between each station distributed in each formation. However, it is possible that the high degree of dominance is a factor to indicate an inequality between the true diversity and the species richness identified. These results provide new analytical and paleoecological criteria for better understanding depositional environments and fossil associations where the spatial distribution of benthic organisms, richness and abundance provide a valued window to Cambrian biotas. The structure of the marine community of the El Sahuaral area has a great affinity with other Cambrian communities, such as those from the Stephen Formation (Burgess Shale, British Columbia) and the Chengjiang biota of the Yangtze Shelf deposits in South China.

Original languageEnglish
Pages (from-to)607-620
Number of pages14
JournalPalaeoworld
Volume31
Issue number4
DOIs
StatePublished - Dec 2022

Bibliographical note

Funding Information:
The authors appreciate the financial support provided by CONACYT through a scholarship award given to the first author, and to the project PRODEP UNISON-PTC-301 “Paleoecología de los ecosistemas marinos del Cámbrico de Sonora, México: Bioestratigrafía, Paleobiogeografía y su relación con el cratón de Norteamérica”. We also thank the Departamento de Investigaciones Científicas y Tecnológicas and the Posgrado en Biociencias from the Universidad de Sonora, México. We are also grateful to Dr. Robert B. Blodgett and an anonymous reviewer that help us to improve this manuscript.

Funding Information:
The authors appreciate the financial support provided by CONACYT through a scholarship award given to the first author, and to the project PRODEP UNISON-PTC-301 “Paleoecología de los ecosistemas marinos del Cámbrico de Sonora, México: Bioestratigrafía, Paleobiogeografía y su relación con el cratón de Norteamérica”. We also thank the Departamento de Investigaciones Científicas y Tecnológicas and the Posgrado en Biociencias from the Universidad de Sonora, México. We are also grateful to Dr. Robert B. Blodgett and an anonymous reviewer that help us to improve this manuscript.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Cambrian
  • Mexico
  • Sonora
  • community diversity
  • paleoecology

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