Albertonykus

Albertonykus is a diminutive alvarezsaurid theropod discovered in the Late Cretaceous Horseshoe Canyon Formation of Alberta, Canada. Measuring approximately one metre in length and weighing only about four kilograms, it represents the smallest known non-avian dinosaur from its habitat. Like its Asian and South American relatives, Albertonykus possessed extremely shortened, robust forelimbs dominated by a single massive, hyper-developed thumb claw. Its long, slender legs indicate it was an agile, fleet-footed runner. Rather than hunting large prey, Albertonykus was an ant- or termite-eater. Its stocky forearms were mechanically suited for tearing open rotting timber and termite mounds, while its tiny, delicate jaws likely housed small teeth capable of scooping up fleeing colonial insects. Its discovery showed that specialised insectivorous alvarezsaurids thrived in high-latitude North American woodland ecosystems.

It is the northernmost known alvarezsaurid, with robust thumb claws adapted for ripping into rotting wood.

Where and when

Albertonykus lived in the Late Cretaceous, from 71 to 68 million years ago (Maastrichtian age). Its remains come from Canada, in the Horseshoe Canyon Formation.

The numbers

Length 1 m (estimates run from 0.9 to 1.1 m). Mass about 3.9 kg. Hip height about 0.4 m. That is 0.6 human-lengths, or 0.09 of a double-decker bus. These are estimates from fragmentary remains; fields marked estimated by the site are length, mass, hip height.

Compare Albertonykus with a bus Place on the timeline