New insights into the diversity dynamics of Triassic conodonts

Abstract

In this paper, we examine the diversity trends and the evolutionary patterns of Triassic conodonts through a newly powered large-scale data-set compiled directly from the primary literature. Paleodiversity dynamics analyses have been undertaken by working at the species level and using a system of time units based on biozone subdivisions for a fine temporal level resolution. The role of heterogeneous duration of taxa in diversity estimates has been evaluated through the probabilistic profiles. Results reveal three different stages in the diversity behaviour of Triassic conodonts from standing metrics delimited by two inflections at the mid-Anisian and mid-Carnian. Survivorship analysis supports this pattern. Origination–extinction metrics report a diversification pattern characterised by important fluctuations during the Lopingian–Induan (earliest Triassic), the early-middle Olenekian (Early Triassic) and the Anisian–Ladinian transitions (Middle Triassic), as well as in the early Late Triassic. In addition, two clear diversification peaks are observed in the late Carnian and in the end-Norian. Reported patterns are interpreted in the context of deep extinction and environmental instability by documenting the biological signal of the main diversification and turnover patterns observed from such records. This study emphasises the singularity behaviour of diversity trends derived from the conodont record.

Keywords::

• diversity estimates
• conodonts
• Triassic
• extinction dynamics
• paleontological data analysis
• probability of surviving

Acknowledgements

We would like to thank two anonymous reviewers for all the suggestions and corrections that considerably improved the quality of our work. CMP benefits from a Marie Curie FP7-People IEF 2011- 299681 fellowship, and PP was supported by the Chinese Academy of Sciences (Young International Scientist Grant ‘2010Y2ZA02’) and by the ‘Agencia Española de Cooperación Internacional para el Desarrollo’ of the Ministry of Foreign Affairs and Cooperation of Spain (MAEC-AECID).