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Link to original content: https://pubmed.ncbi.nlm.nih.gov/37464026
An extraordinary fossil captures the struggle for existence during the Mesozoic - PubMed Skip to main page content
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. 2023 Jul 18;13(1):11221.
doi: 10.1038/s41598-023-37545-8.

An extraordinary fossil captures the struggle for existence during the Mesozoic

Gang Han  1   2 , Jordan C Mallon  3   4 , Aaron J Lussier  5 , Xiao-Chun Wu  6 , Robert Mitchell  7 , Ling-Ji Li  8
Affiliations

An extraordinary fossil captures the struggle for existence during the Mesozoic

Gang Han et al. Sci Rep. .

Erratum in

Abstract

Dinosaurs and mammals have coexisted for the last ~ 230 million years. Both groups arose during the Late Triassic and diversified throughout the Mesozoic and into the Cenozoic (the latter in the form of birds). Although they undoubtedly interacted in many ways, direct fossil evidence for their interaction is rare. Here we report a new fossil find from the Lujiatun Member of the Lower Cretaceous Yixian Formation of China, showing a gobiconodontid mammal and psittacosaurid dinosaur locked in mortal combat. We entertain various hypothesized explanations for this association, but the balance of the evidence suggests that it represents a predation attempt on the part of the smaller mammal, suddenly interrupted by, and preserved within, a lahar-type volcanic debris flow. Mesozoic mammals are usually depicted as having lived in the shadows of their larger dinosaurian contemporaries, but this new fossil convincingly demonstrates that mammals could pose a threat even to near fully-grown dinosaurs. The Yixian Formation-and the Chinese fossil Jehol Biota more broadly-have played a particularly important role in revealing the diversity of small-bodied dinosaurs and other fauna. We anticipate that the volcanically derived obrution deposits specific to the Lujiatun Member will likewise continue to yield evidence for biotic interactions otherwise unknown from the rest of the fossil record.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Psittacosaurus lujiatunensis-Repenomamus robustus pair (WZSSM VF000011) locked in mortal combat. Insets depict (left to right): hand of R. robustus wrapped around lower jaw of P. lujiatunensis, teeth of R. robustus embedded in ribs of P. lujiatunensis, hind foot of R. robustus wrapped around lower hindlimb of P. lujiatunensis. Scale bar equals 10 cm.
Figure 2
Figure 2
Life restoration showing Repenomamus robustus grappling with Psittacosaurus lujiatunensis. Artwork by Michael Skrepnick. Reproduced with permission.
Figure 3
Figure 3
Phylogenetic generalized least squares models. (A) Brownian motion, (B) Ornstein–Uhlenbeck, (C) Pagel’s λ, (D) ACDC. Linear models show the relationship between predator body mass and maximum prey body mass for solitary (blue) and pack (green) hunters. Shaded areas represent the 95% confidence intervals; dotted lines represent 95% prediction intervals. The association between the Repenomamus robustus and Psittacosaurus lujiatunensis documented here (red star), and the predicted association of somatically mature examples of these species (black star), are well within the 95% prediction intervals for each model and hunting style.
Figure 4
Figure 4
Species diversity statistics for the Lujiatun Member of the Lower Cretaceous Yixian Formation of China. (A) Rarefaction curve showing undersampled richness of Lujiatun Member. (B) Voronoi diagram showing uncorrected relative abundance data. (C) Voronoi diagram showing relative abundance corrected for taphonomic size bias. (D) Trophic biomass pyramid corrected for taphonomic factors. Psittacosaurus lujiatunensis makes up 85.9% of all primary consumer biomass in the restored terrestrial vertebrate fauna. Silhouette credits (from phylopic.org): DiBgd (sauropod); T. Dixon (maniraptoriform); S. Hartman (carnosaur, tyrannosauroid); J. Headden (Psittacosaurus); N. Mongiardino Koch (lizard); V. Sinkkonen (ornithischian); E. Willoughby (amphibian); M. Zica (mammal).
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