Document Type

Article

Publication Date

1-30-2024

Keywords

neuron counts, telencephalic neurons, mesozoic dinosaurs, pterosaurs, behavioral proxies, life history traits, theropods, tyrannosaurus rex, encephalization, phylogenetically informed modeling, endocranial measurements, neurological variables, cognitive complexity, metabolic rate, flawed proxies, integrative studies

Abstract

Recent years have seen increasing scientific interest in whether neuron counts can act as correlates of diverse biological phenomena. Lately, Herculano-Houzel (2023) argued that fossil endocasts and comparative neurological data from extant sauropsids allow to reconstruct telencephalic neuron counts in Mesozoic dinosaurs and pterosaurs, which might act as proxies for behaviors and life history traits in these animals. According to this analysis, large theropods such as Tyrannosaurus rex were long-lived, exceptionally intelligent animals equipped with “macaque- or baboon-like cognition” whereas sauropods as well as most ornithischian dinosaurs would have displayed significantly smaller brains and an ectothermic physiology. Besides challenging established views on Mesozoic dinosaur biology, these claims raise questions on whether neuron count estimates could benefit research on fossil animals in general. Here, we address these findings by revisiting Herculano-Houzel’s (2023) work, identifying several crucial shortcomings regarding analysis and interpretation. We present revised estimates of encephalization and telencephalic neuron counts in dinosaurs, which we derive from phylogenetically informed modeling and an amended dataset of endocranial measurements. For large-bodied theropods in particular, we recover significantly lower neuron counts than previously proposed. Furthermore, we review the suitability of neurological variables such as neuron numbers and relative brain size to predict cognitive complexity, metabolic rate and life history traits in dinosaurs, coming to the conclusion that they are flawed proxies of these biological phenomena. Instead of relying on such neurological estimates when reconstructing Mesozoic dinosaur biology, we argue that integrative studies are needed to approach this complex subject.

Comments

Version 2 (January 13, 2024)

Faculty

Faculty of Humanities & Social Sciences (FHASS)

Version

Pre-print

Terms of Use

Terms of Use for Works posted in SOURCE.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Original Publication Citation

Caspar, K.R., Gutiérrez-Ibáñez, C., Bertrand, O.C., Carr, T., Colbourne, J., Erb, A. George, H., Holtz Jr, T.R., Naish, D., .Wylie, D.R., & Hurlburt, G.R. (2024). How smart was T. rex? Testing claims of exceptional cognition in dinosaurs and the application of neuron count estimates in palaeontological research. bioRxiv. https://doi.org/10.1101/2024.01.10.575006

Download

Share Feedback

Share

COinS