Founder’s Briefs: An occasional series where Mongabay founder Rhett Ayers Butler shares analysis, perspectives and story summaries.

Turtles and tortoises have outlived dinosaurs, endured ice ages, and survived the shuffling of continents. Yet despite their evolutionary stamina, these ancient mariners and land dwellers now find themselves in peril. A sweeping global assessment published in Nature Communications offers the most comprehensive analysis to date of extinction risks facing the order Testudines, which includes turtles, tortoises and terrapins — and the results are grim.

More than half of the 378 evaluated species are either threatened or already extinct. Particularly imperiled are those with large body sizes, narrow geographical ranges, or high ecological distinctiveness. The Indo-Malayan region, home to species such as the Asian giant softshell turtle (Pelochelys cantorii) and the Assam box turtle (Cuora praschagi), has emerged as a hotspot of chelonian crisis. Entire families, including Trionychidae (softshell turtles) and Geoemydidae (Asian river turtles), are on the brink.

The study doesn’t stop at diagnosis. Using models that incorporate ecological traits, geographical distributions and anthropogenic pressures, researchers projected extinction risk for 43 data-deficient species — those whose extinction threat hasn’t been assessed for the IUCN Red List. Nearly one in five of these is likely threatened, including the Sicilian pond turtle (Emys trinacris) and the flatback turtle (Natator depressus), which nests exclusively on northern Australian shores.

But perhaps most alarming is the study’s conclusion that turtles’ evolutionary adaptations are unfolding far too slowly to keep pace with today’s environmental shifts. Traits such as body size or reproductive lifespan evolve over millennia. Meanwhile, climate change, habitat degradation and human expansion are advancing at a speed that outstrips turtles’ ability to adapt by several orders of magnitude.

There are glimmers of hope. Some species are demonstrating behavioral adaptability, such as shifting nest timing or location. Yet the broader picture remains one of biological inertia clashing with planetary acceleration. For creatures that once epitomized resilience, the Anthropocene may prove too swift and too brutal a test.

Read related coverage by Mongabay’s Liz Kimbrough here.

Banner image: Giant Galápagos tortoises. Image by Rhett A. Butler/Mongabay.