Iguanodon, Ouranosaurus and Lurdusaurus as quadrupeds + Cretaceous terrestrial ecosystem productivity (free pdfs)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New papers:

Free pdf:

Jordan Gônet, Ronan Allain & Alexandra Houssaye (2026)
Locomotor reassessment of Iguanodon, Ouranosaurus and Lurdusaurus (Dinosauria, Ornithopoda) using osteological correlates.
Fossil Record 29(1): 71-86.
doi: https://doi.org/10.3897/fr.29.173614
https://fr.pensoft.net/article/173614/list/9/


Large ornithopod dinosaurs have been successively described as quadrupeds, bipeds and facultative bipeds. Here we study the case of three ankylopollexians (Iguanodon bernissartensis, Ouranosaurus nigeriensis and Lurdusaurus arenatus) for which locomotion remains debated. We examine in detail their appendicular skeleton, focusing on osteological features that were previously associated with either bipedality or quadrupedality in dinosaurs. We compare our observations with data obtained for 12 saurischians and 32 ornithischians whose bipedal or quadrupedal locomotion is unambiguous. Iguanodon and Ouranosaurus score as quadrupeds for nine of the eleven correlates used in this study and are therefore best interpreted as obligate quadrupeds—contrasting with previous hypotheses of facultative bipedalism in Ankylopollexia—although this is sensitive to how hadrosaur locomotion is assessed. Lurdusaurus is found among quadrupeds for all the osteological correlates employed and is thus considered as an obligate quadruped, implying that obligate quadrupedality in ornithopods arose long before the hadrosaurs. Moreover, its extreme humeral and femoral eccentricity, along with its very short metatarsus, indicate graviportality, making Lurdusaurus the first graviportal ornithopod. Further biomechanical investigations are definitely needed to fully appreciate the locomotion of this unique taxon. Osteological correlates appear to be useful tools for investigating the transition to quadrupedalism in ornithopods, and may provide a basis for more comprehensive reconstructions of locomotor and postural evolution across diverse dinosaur lineages.

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Free pdf:

Ian Alexander Taylor, Richard Lupia & Caitlin Hodges (2026)
Modeling net primary productivity in a Cretaceous terrestrial ecosystem: a probabilistic approach
CATENA 265: 109890
doi: https://doi.org/10.1016/j.catena.2026.109890
https://www.sciencedirect.com/science/article/pii/S0341816226001001

Highlights

Introduces a probabilistic soil‑carbon framework for reconstructing paleo-NPP from paleosols.
Validates soil-derived NPP estimates against MODIS across diverse modern ecosystems.
Demonstrates robust model performance in organic-rich, oxygen-limited environments.
Shows lower productivity in fern-dominated paleosols relative to angiosperm-rich sites.
Quantifies primary production in a Campanian floodplain supporting megaherbivore communities.

Abstract

The Late Campanian Big Cedar Ridge (BCR) fossil site provides a well-preserved record of a rapidly buried ecosystem, offering a unique opportunity to reconstruct past environmental conditions. Understanding net primary productivity (NPP) in such ecosystems is crucial for assessing the energy available to sustain large herbivorous dinosaurs. However, quantitative estimates of ecosystem productivity in deep time remain rare, as most reconstructions rely on qualitative indicators or indirect climate proxies rather than mechanistic, data-driven approaches. Existing methods often lack probabilistic treatment of uncertainty and cannot easily be validated against modern ecosystems. Here, we present a probabilistic permutation of an existing carbon cycling model that estimates paleo-NPP using total organic carbon (TOC) from well-preserved paleosols. This approach integrates soil carbon stocks with decomposition rate estimates, providing a probabilistic approach to reconstructing ancient productivity.

When tested in modern ecosystems, the model demonstrates strong predictive performance, particularly in high-TOC, oxygen-limited environments. Applied to BCR, the model estimates a mean NPP of approximately 1816 g C m−2 yr−1, a value comparable to modern tropical and subtropical wetlands. These findings suggest that this Campanian ecosystem was highly productive, capable of sustaining diverse megaherbivore populations and demonstrate the utility of probabilistic NPP modeling for reconstructing the energy budgets of extinct ecosystems and constraining their potential herbivore carrying capacities.

By establishing a baseline for estimating primary productivity in deep time, this methodology can provide new insights into the relationship between ecosystem productivity, dinosaur diversity, and paleoecological structure. The model offers a framework for future studies, enhancing our understanding of how primary productivity shaped and was shaped by terrestrial ecosystems during the Mesozoic. Unlike existing paleo-productivity proxies, this approach produces spatially explicit, probabilistic NPP estimates that can be directly validated against modern ecosystems.

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