The Temnospondyli were a group of primitive terrestrial vertebrates and possible ancestors of today’s amphibians. They lived from the early Carboniferous period, around 340 million years ago, until the early Cretaceous period, about 110 million years ago, and inhabited large parts of the Earth. Fossil finds show that these "proto-amphibians" produced an incredible diversity of life forms and adaptations over their more than 200 million years of existence, allowing them to colonize a wide variety of habitats. Whether in water, near water, or on land, their distribution was so widespread that the fossilized remains of this animal group can be found on every continent today.
A team led by Raphael Moreno, a PhD student in the Paleontology Department at the Natural History Museum of Stuttgart, investigated how the spatial distribution of these amphibians changed over time and how different environmental factors influenced their dispersal. The period studied ranges from the Middle Triassic, about 245 million years ago, to the Late Triassic, approximately 232 million years ago.
For their study, they used data from actual fossil sites as well as simulations of the climate and environmental conditions of that time. This combination allowed them to model the potential distribution of the species in the studied time span.
Interestingly, during the period studied, geographical barriers had a much smaller impact on the distribution than the climate did. During the Triassic period, there was an overall decline in swampy and humid areas and an increase in arid landscapes, which represented challenging conditions for many temnospondyls.
By using the simulations, the researchers were able to trace the routes by which the animals probably spread, thus "connecting" many of today’s fossil sites. The investigations revealed that the various amphibious temnospondyl groups followed the best climatic conditions along waterways. Despite their high adaptability, they mostly preferred areas with high temperatures, heavy rainfall, and low seasonality.
With these insights, the study provides a basis for further investigations that delve even deeper into the expansion and distribution of the Temnospondyli. At the same time, the models and simulations used can be flexibly applied to any other fossil-preserved organisms to study their distribution patterns.
The results were published in the journal "Palaeontology."