Located in East Greenland’s Fleming Fjord Formation, recently identified 210-million-year-old lungfish burrows provide insight into the fluctuating nature of the Late Triassic climate throughout ancient Greenland.
The fossilized burrows suggest that the lungfish had a strategy of burrowing into the mud to survive during seasonal droughts in late Triassic Greenland through a biological process called “sprouting,” waiting for the environment to become habitable again.This research, published on ResearchGate, has increased our understanding (or lack thereof) of the Norian-Raetian transition periods, demonstrating that environmental stress – not fertile ecosystems – determined these ecosystems during the Late Triassic.
Geologists and paleontologists are reconstructing the ancient world from these “holes” in the rock, where animals retreated to live underground.
Greenland burrows reveal lungfish survival 210 million years ago
Researchers have discovered “trace fossils” made by lungfish (cylindrical structures) in sedimentary layers deposited in ancient lake basins as a result of the geological processes of Fleming Strait formation. Unlike body fossils, which record an organism’s shape and appearance, these burrows document an organism’s actual behavior, specifically its behavior of burrowing in the substrate about 210 million years ago to escape desiccation.
Greenland’s 210-million-year-old fish secret
The discovery of these burrows provides evidence that lungfishes from the Triassic were able to enter a phase of diapause (known as aestivation) as a means of dealing with the conditions of their environment. This physiological response enables lungfish to survive in an intermittent lake; That is, these fish could live in a lake that was vulnerable to drying up of water sources as a result of Pangea’s massive monsoon cycles.
What mud burrows reveal about continental drift in Greenland
According to the book Bulletin of the Geological Survey of Denmark and Greenland (GEUS), the strata containing these burrows consist of mudstones and siltstones; They also preserved the shapes of the cavities since the clay was deposited until it became hard. These types of formations are essential for researchers to further understand how Pangea moved from one place to another and where Greenland was on Earth during this time period.
How small holes in Greenland reshaped Triassic climate models
In addition, these “holes” act as climate indicators to indicate fluctuations in precipitation at high amplitudes. Data published in research by NCBI indicate that high-latitude regions in the Triassic were significantly more thermally hot than previously modeled. It was also drier than current models show. This suggests that the high latitude regions were significantly different from what current models suggested in terms of past atmospheric and climatic conditions.