Located in East Greenland’s Fleming Fjord Formation, the recently identified 210-million-year-old lungfish burrows provide valuable insight into the volatile nature of the Late Triassic climate throughout ancient Greenland. The fossilised burrows indicate that the lungfish had a strategy of digging into the mud to survive the seasonal droughts in Late Triassic Greenland through a biological process called ‘aestivation’, waiting for the environment to become hospitable again.This research, published on ResearchGate, has increased our understanding (or lack thereof) of Norian-Rhaetian transitional periods, showing that environmental stress – not lush ecosystems – defined these ecosystems during the Late Triassic period. Geologists and palaeontologists are reconstructing the ancient world from these ‘holes’ in the rock, where animals retreated to survive beneath the earth’s surface.
Greenland burrows reveal lungfish survival 210 million years ago
Researchers discovered ‘trace fossils’ made by lungfish (the cylindrical structures) in the sedimentary layers deposited into ancient lake basins as a result of the geological processes of Fleming Fjord Formation. Unlike body fossils, which record an organism’s form and appearance, these burrows document an organism’s actual behaviour, specifically its behaviour of burrowing into the substrate approximately 210 million years ago to escape from dehydration.
The 210-million-year-old secret of Greenland’s fish
The discovery of these burrows provides evidence that lungfish from the Triassic period were capable of entering into a phase of dormancy (known as aestivation) as a method for coping with the conditions of their environment. This physiological response enabled lungfish to survive in an intermittent lake; that is, these fish could survive in a lake that was subject to the drying out of water sources as a result of Pangaean megamonsoonal cycles.
What mudstone burrows reveal about Greenland’s continental drift
According to the book ‘Geological Survey of Denmark and Greenland (GEUS) Bulletin’, the strata that have these burrow holes are made up of mudstones and siltstones; they also kept the shapes of the cavities from the time the mud was deposited until it became hard. These types of formations are critical to researchers to continue to understand how Pangaea moved from one place to another and where Greenland was on the Earth during this time period.
How Greenland’s tiny holes reshaped Triassic climate models
In addition, these ‘tiny holes’ act as climate proxies for indicating fluctuations in precipitation at high amplitudes. The data published in a research on NCBI indicate that the Triassic high-latitude regions were significantly more thermally elevated than what was modelled in previous projections. Also, they were much drier than the current models show. This suggests that the high-latitude regions were significantly different from what existing models suggested regarding past atmospheric and climatic conditions.
