From Newsgroup: sci.bio.paleontology

https://www.science.org/doi/10.1126/science.adx7390

Earliest oceanic tetrapod ecosystem reveals rapid complexification of
Triassic marine communities


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 midrCoEarly
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.
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From Newsgroup: sci.bio.paleontology

On 11/14/25 10:00 AM, erik simpson wrote:

https://www.science.org/doi/10.1126/science.adx7390

Earliest oceanic tetrapod ecosystem reveals rapid complexification of Triassic marine communities

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 midrCoEarly
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.

Cool. What's their date for the Permian/Triassic boundary?
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From Newsgroup: sci.bio.paleontology

On 11/14/25 8:15 PM, John Harshman wrote:

On 11/14/25 10:00 AM, erik simpson wrote:

https://www.science.org/doi/10.1126/science.adx7390

Earliest oceanic tetrapod ecosystem reveals rapid complexification of
Triassic marine communities


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
midrCoEarly 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.

Cool. What's their date for the Permian/Triassic boundary?

Unbelievably precise, but 249.6 Mya.

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