Earliest oceanic tetrapod ecosystem reveals rapid complexification of Triassic marine communities

2025/11/13 by Aubrey J. Roberts, Maciej Ruciński, Benjamin P. Kear +5 · 2 voices · 2 citations
Earth and Planetary Sciences · Environmental Science · #Paleontology and Evolutionary Biology #Ichthyology and Marine Biology #Paleontology and Stratigraphy of Fossils

paper · doi:10.1126/science.adx7390

openalex publication_date 2025/11/13 · openalex created_date 2025/11/13 · openalex updated_date 2026/07/23

Abstract

Tetrapods invaded oceanic environments after the cataclysmic end-Permian mass extinction (EPME), with temnospondyl amphibian to reptile-dominated assemblages succeeding across the Early Triassic [~251.9 to 247.2 million years ago (Ma)]. However, conflicting fossil occurrences, divergence estimates, and stratigraphic time averaging make the tempo of this landmark evolutionary transition uncertain. In this work, we describe an oceanic tetrapod ecosystem from a condensed mid-Early Triassic (early Spathian, ~249 Ma) bone bed on the arctic island of Spitsbergen. Apex predator ichthyosaurians, small-bodied ichthyopterygians, durophagous ichthyosauriforms, semiaquatic archosauromorphs, euryhaline temnospondyls, coelacanths, lungfish, ray-finned fish, and sharks formed an unexpectedly complex trophic network. Comparative diversity analyses further show that heterogeneous marine vertebrate communities were well established by the late-earliest Triassic (Dienerian-Smithian, ~251 Ma) and integrated fully variegate tetrapod niches by ~3 million years after the EPME.

Citations

• Nonmetric Multidimensional Scaling: A Numerical Method
• The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades
• Marine Early Triassic Actinopterygii from the Candelaria Hills (Esmeralda County, Nevada, USA)
• The last giants: New evidence for giant Late Triassic (Rhaetian) ichthyosaurs from the UK
• TOOTH MORPHOTYPES SHED LIGHT ON THE PALEOBIODIVERSITY OF MIDDLE TRIASSIC TERRESTRIAL VERTEBRATE ECOSYSTEMS FROM NE IBERIAN PENINSULA (SOUTHWESTERN EUROPE)

Cited by

• An in utero foetus of the Middle Triassic ichthyosaur Besanosaurus leptorhynchus from Monte San Giorgio, Italy
• New insights on the depositional environment and dynamics of the lowermost Triassic in Svalbard: linking the Sørkapp-Hornsund High to western and central Spitsbergen

Discussions

• As always, there are studies that involve temnospondyls + other tetrapods: Roberts et al: Early Tr marine recovery in Svalbard: doi.org/10.1126/scie... Scharling et al: Tooth morphotypes in Svalbard [bsky, 4 points, 1 comments]
• Ecossistema mais antigo de tetrápodes oceânicos revela rápida complexificação das comunidades marinhas do Triássico doi.org/10.1126/scie... [bsky, 2 points, 0 comments]

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