Why these legless lizards are named after glass and how they conquered the world

Nature · Published 3 October 2026 Swipe more like this →

In short: The Anguinae subfamily, known as glass lizards, earned their brittle reputation from tails that snap off with alarming ease. Far from being simple snakes, these legless reptiles have a complex evolutionary history that spans continents, crossing ancient land bridges to establish a presence across North America, Europe, Asia, and North Africa.

The evolutionary journey of the Anguinae began in the early Eocene, roughly 48.6 million years ago, when they first emerged in Europe. These creatures descended from North American ancestors that migrated across the Thule Land Bridge from Greenland. As the Turgai Strait dried during the early Oligocene, they expanded into Asia, eventually traversing the Bering Land Bridge to return to North America by the Miocene epoch.

While these lizards are famously legless, the group retains subtle reminders of their ancestral past. Certain genera, specifically Hyalosaurus and Pseudopus, still possess vestigial hindlegs, though these are entirely absent in other members of the subfamily. Today, the group is diverse, comprising six distinct genera including Dopasia, Hyalosaurus, the extinct Ophisauromimus, Ophisaurus, Pseudopus, and the familiar Anguis, or slowworms. Their diet consists primarily of insects and various other invertebrates.

The physical scale of these animals varies significantly across the subfamily. The largest extant species is the Sheltopusik, or Pseudopus apodus, which can grow to an impressive length of 120 centimetres, or 47 inches. Their common names—glass lizards, glass snakes, and slow worms—allude to their fragile tails, which can break off under stress. This unique biological trait, combined with their wide geographic distribution and ancient migration patterns, makes the Anguinae a fascinating study in vertebrate adaptation and historical biogeography.

The subfamily remains a subject of ongoing scientific classification, with researchers like Lavin and Girman providing updated insights into their relationships as recently as 2019. By tracking their movement across geological time and analyzing their vestigial features, scientists continue to piece together the complex story of how these resilient reptiles successfully navigated shifting landscapes to survive across multiple continents for tens of millions of years.

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