Study finds evidence Earth's axis shifted rapidly during dinosaur era

Imagine Earth's solid crust and mantle suddenly rotating beneath your feet, while the planet's spin axis stays fixed. This is not the slow drift of continents across the globe, nor the wandering of magnetic poles. It is something stranger: the entire rocky shell of the planet reorienting itself relative to the axis around which it spins. A new study published in Science suggests this phenomenon, called true polar wander, happened several times during the age of dinosaurs, with the most dramatic episodes occurring roughly 150 to 140 million years ago and again 100 to 90 million years ago.

Mathew Domeier and colleagues at the University of Oslo approached the question through an unexpected archive: the ancient patterns of where oceans flooded continents and where they retreated. Rather than relying solely on magnetic minerals locked in ancient rocks—the traditional method for detecting polar wander—they examined 320 million years of global sea-level maps, comparing them at ten-million-year intervals to identify where water advanced and where it receded. The logic is elegant. When the solid Earth lurches relative to its rotational bulge, the oceans respond almost immediately, while the mantle takes longer to reshape itself. This mismatch creates a distinctive four-lobed pattern: two regions gain water while two lose it. Using statistical methods, the researchers tested whether observed flooding patterns matched the geometry expected from true polar wander.

The results identified four intervals with statistically significant signals. The strongest evidence emerged from the Late Jurassic and earliest Cretaceous, between 150 and 140 million years ago. During this period, seas rose across parts of South America, Antarctica, and eastern Asia, while southwestern North America, western Europe, and eastern Australia experienced retreating waters. The data suggested a clockwise reorientation around an axis near 58 degrees east longitude. A second powerful signal appeared between 100 and 90 million years ago, with the pattern reversed: South America, western and southern Africa, and eastern Asia saw water retreat, while much of North America and Europe experienced advancing seas. This episode indicated rotation in the opposite direction around an axis near 53 degrees east. Two other intervals—200 to 190 million years ago and 30 to 20 million years ago—crossed the statistical threshold but showed weaker signals and less convincing fits to the observed patterns.

True polar wander occurs because Earth is not a perfect sphere. Rotation creates an equatorial bulge, and the planet tends to arrange its internal mass so that its largest moment of inertia aligns with the spin axis. Mantle convection, sinking tectonic slabs, and other processes constantly redistribute mass within the planet. If that distribution becomes sufficiently unbalanced, the solid Earth can reorient itself—a rebalancing act that happens on geological timescales but can occur in rapid bursts rather than slow, continuous motion. The study's methodology suggests these detected events moved at rates of at least about 0.6 degrees per million years, which qualifies as rapid by geological standards.

The significance of this work lies partly in its independence from existing methods. Paleomagnetic reconstructions—the dominant approach for detecting polar wander—depend on interpreting magnetic signatures in rocks, a process complicated by the need to separate whole-Earth reorientation from ordinary plate tectonics. The sea-level approach offers a largely separate line of evidence. When the strongest Mesozoic episodes detected through flooding patterns align with some paleomagnetic reconstructions, the case becomes harder to dismiss as an artifact of a single technique. Yet the field remains contentious. A 2025 study in AGU Advances reconstructed large but generally slow polar wander over the past 320 million years and found no evidence for the rapid Cretaceous and Late Jurassic oscillations this new work proposes. A 2024 Nature Communications paper, by contrast, reported an approximately 12-degree southward shift followed rapidly by about 10 degrees of northward movement around the Jurassic-Cretaceous boundary.

If rapid true polar wander did occur repeatedly during the Mesozoic, the implications extend far beyond geography. Continents could move quickly through climate belts, altering rainfall, temperature, marine environments, and habitats without requiring equivalent changes in atmospheric greenhouse gases. Climate simulations show that including true polar wander in models can change reconstructed regional temperatures by more than 20 degrees Celsius during parts of the Mesozoic. The geological record increasingly suggests that Earth's solid exterior, while appearing stable on human timescales, has sometimes been far more restless than we once believed.