These Ancient Fish Burrows Are Quietly Rewriting What We Know About Dinosaur Life

A scientific discovery from East Greenland is now giving insight into the functioning of ancient ecosystems of the Late Triassic era, approximately 210 million years ago, via one of the most unlikely means, the fossil burrows of lungfishes.

The burrows found in the Carlsberg Fjord Member sediments were made by lungfish that remained dormant by burrowing underground during periods of drought, a process called aestivation, which is an analogous process to hibernation but induced by high temperatures and dry weather.

This finding, as stated in a study article in Paleogeography, Paleoclimatology, Palaeoecology, indicates that the climate of this region was seasonally dry and not continuously humid, thus debunking previous theories regarding the climate of the Norian age.

Evidence of seasonal drought

The fact that the fossils belong to lungfish burrows indicates that lakes and other water sources in the area did not exist permanently. Instead, they came into being depending on rainfall, meaning that at one point, there were dry spells where the land would be devoid of any source of water.

From the study, it can be observed that lungfish create such burrows in order to survive times when water is not readily available, making them good indicators of drought periods. According to the article, they offer an indication of biological signals of environmental stress that cannot easily be determined from sediments or rocks.

As is observed in a similar study, such burrows are also an indicator of “episodes when water bodies became ephemeral, and habitats were subject to drought stress”.

What this means for dinosaurs

One of the main implications of the findings is that our perception of the lifestyle of these dinosaurs from the Late Triassic is greatly altered. Large herbivorous dinosaurs, sauropodomorphs, also inhabited these areas, meaning that they had to endure fluctuations in water availability and changes in vegetation.

According to the same Greenland study, dinosaurs probably coped with the problem through behavioral changes, seasonal migration, and habitat change due to water deficiency. In other words, the dry environment did not hinder dinosaurs' survival; on the contrary, they managed to adjust their lifestyle and behavior successfully.

Experts state that being able to inhabit places with only a temporary water supply proves the resilience of dinosaurs because they somehow found ways to sustain themselves.

A new perspective on ancient ecosystems

With such a finding, paleontologists can now say that dinosaurs lived in areas where climatic conditions were not consistent and stable but rather fluctuated between abundance and scarcity. Dinosaurs had to constantly adapt to their surroundings, and through the correlation of fossilized remains and behavior patterns, researchers have managed to reconstruct how dinosaurs used to live in the Late Triassic Period.

Overall, it can be concluded that dinosaurs were living in resilient and seasonally driven ecosystems. Through the correlation of fossil evidence and animal behaviors, researchers managed to uncover how dinosaurs used to survive in the Late Triassic Period.

In other words, the fish burrow is contributing to understanding dinosaur behaviors and movements.