VLa question de savoir si les dinosauridés avaient déjà commencé à décliner avant l’impact sur la Terre de l’asteroîd Chicxulub est régulièrement posée. Aujourd’hui l’accord semble se faire
sUne équipe dirigée par Christopher Dean, University College, London, a rassemblé une banque de données de 800 spécimens d’ossements fossiles provenant de quatre espèces de dinosaures vivant en Amérique du Nord entre 84 et 66 millions d’années, incluant le Tyrannosaurus Rex et le Tricerartops. Or leur nombre était resté stable durant cette période.
Autrement dit, sans cet astéroïde, les dinosaures auraient continué à occuper la Terre. Ils seraient probablement devenus de plus en plus intelligents et dominateurs. Certains d’entre eux envisageraient peut-être aujourd’hui des missions sur la Lune ou sur Mars.
Source
Current Biology.doi.org/pgkmArticleVolume 35, Issue 9p1973-1988.e6May 05, 2025 Open access
The structure of the end-Cretaceous dinosaur fossil record in North America
Christopher D. Dean1,9 christopher.dean@ucl.ac.uk ∙ Alfio Alessandro Chiarenza1 ∙ Jeffrey W. Doser2 ∙ … ∙ Paul J. Valdes3,4 ∙ Richard J. Butler8 ∙ Philip D. Mannion1 … Show more
Highlights•
.The probability of detecting dinosaurs decreases toward the end-Cretaceous•
.Sampling intensity does not impact the probability of dinosaur detection
•Detection probability is driven by geologic outcrop and present-day land cover•
.Geological sampling biases cloud our view of end-Cretaceous dinosaur diversity
Summary
Whether non-avian dinosaurs were in decline prior to their extinction 66 million years ago remains a contentious topic. This uncertainty arises from spatiotemporal sampling inconsistency and data absence, which cause challenges in distinguishing between genuine biological trends and sampling artifacts. Consequently, there is an inherent interest in better quantifying the quality of the data and concomitant biases of the dinosaur fossil record. To elucidate the structure of this record and the nature of the biases impacting it, we integrate paleoclimatic, geographic, and fossil data within a Bayesian occupancy modeling framework to simultaneously estimate the probability of dinosaurs occupying and being detected in sites across North America throughout the latest Cretaceous for the first time. We find that apparent declines in occupancy generated from the raw fossil record do not match modeled occupancy probability, which generally remained stable throughout the latest Cretaceous. Instead, they coincide with decreased probability of detecting dinosaur occurrences, despite high overall sampling during this interval. By incorporating model covariates, we additionally reveal that detection probability is directly and significantly influenced by the available area of geological outcrop and modern land cover. Our findings offer evidence that traditional comparisons of diversity estimates between time intervals are likely inaccurate due to underlying structural issues in the geological record operating at both local and regional scales. This study underscores the utility of occupancy modeling as a novel approach in paleobiology for quantifying the impact of heterogeneous sampling on the available fossil record.
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