How to grow small? The perspective of the iconic predator Dimetrodon
The sail-backed predator Dimetrodon is one of the most iconic animals of the early Permian – long before dinosaurs dominated the Earth. Most known species of this early relative of mammals reached large body sizes, sometimes up to three metres in length and 250 kilograms. Yet some species remained surprisingly small. A new study by an international research team led by Dr Aurore Canoville of the Friedenstein Stiftung Gotha and the Museum für Naturkunde Berlin, now shows that these small body sizes were achieved through very different growth strategies.
The study focuses on the two smallest known species: Dimetrodon natalis from North America and Dimetrodon teutonis - the only Dimetrodon species discovered outside North America to date - from the Bromacker fossil site in Thuringia. Whilst Dimetrodon natalis was long considered the smallest known species, Dimetrodon teutonis proved to be even smaller.
To find out why these animals grew so small, the research team analysed the microscopic structure of their fossilised bones. Bone tissue preserves information about growth rates and developmental processes, thereby providing direct insights into the life history of extinct animals.
The findings, published in Scientific Reports, reveal clear differences: Dimetrodon natalis apparently grew rapidly but ceased growing at an early stage. This animal thus reached its small adult size through a shortened development. Dimetrodon teutonis, on the other hand, grew much more slowly over a longer period and presumably did not reach maturity until later.
“This work shows that the method of bone histology can provide us with insights into the actual palaeobiology of long-extinct animals. Who would have thought that these two small species had such different life histories?” says Dr Tom Hübner, curator and head of the BROMACKER project at the Friedenstein Stiftung Gotha.
The researchers attribute the differing growth strategies to the respective environmental conditions. North American Dimetrodon species lived in lowland regions with rich food webs and high predation pressure. Under such conditions, rapid growth could offer advantages for survival and reproduction. The Bromacker ecosystem, by contrast, was characterised by seasonal drought and limited resources. Fossil burrows suggest that potential prey retreated underground during dry periods. For apex predators such as Dimetrodon teutonis, slower growth may therefore have been an adaptation to fluctuating food availability.
“These new findings once again highlight the uniqueness of Bromacker compared to other early Permian sites,” explains Dr Aurore Canoville. “This makes Dimetrodon even more fascinating. Long before dinosaurs dominated the Earth, these early synapsids were already responding with remarkable flexibility to climate, food, competition and predation pressure.”
“These fascinating findings are helping us to build an increasingly comprehensive picture of the Bromacker ecosystem and its potential for many decades of future research,” adds Prof. Jörg Fröbisch of the Museum für Naturkunde Berlin.
Originalpublikation:
Publication: Canoville, A., Knaus, P.L., Marchetti, L. & Fröbisch, J. (2026): Contrasting life history in the diminutive Dimetrodon species from North America and Germany. Scientific Reports. 10.1038/s41598-026-52199-y
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