How to quantify taphonomic alteration? A novel index for fossil fish collections

ABSTRACT

Several biases are often introduced in taxonomic studies due to the transformation or loss of biological information that occurs at different stages from the original depositional ecosystem to the finally selected study sample. We propose the creation of a Taphonomic Alteration Index for Fishes (TAIF) that allows an estimation of the extent of such transformation in the selected sample and its representativeness of the complete record. TAIF is designed as an easily-applicable index that can be used to rapidly assess and compare the taphonomic alteration in different taxa or localities and can also be used as a quantitative variable in other analyses (e.g. morphometrical, statistical). To test TAIF, we have used a sample of Teleostei incertae sedis (N = 190) from the Early Cretaceous of the Las Hoyas site (Cuenca, Spain). Although the obtained TAIF values show some variability, they are in general low, as would be expected for a Konservat-Lagerstätte. The low TAIF values obtained fit with the hypothesis that these fishes inhabited low energy and shallow inland waters, where the effect of anoxia and bacterial sealing would have preserved their remains from degradation. Similar indices could be designed for other taxa based on TAIF.

KEYWORDS:

• Taphonomy
• preservation
• conservation
• fossil fishes
• biases
• Las Hoyas

Acknowledgments

The authors acknowledge the Museo Paleontológico de Castilla-La Mancha for facilitating access to the Las Hoyas collection. We would like to express our gratitude to the three reviewers of the manuscript and the editor Dr. Gareth Dyke for their exhaustive and constructive review which have contributed to improve the present paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are openly available in figshare repository at https://doi.org/10.6084/m9.figshare.22101992.v2

Additional information

Funding

This work was supported by the Spanish Government under Project PID2019-105546GBI00; and the Department of Biology, Universidad Autónoma de Madrid FPI- UAM, under Project BIOUAM02-2019. Carla San Román is supported by a FPI-UAM Ph.D. scholarship from Universidad Autónoma de Madrid.