Astrosaurus, more colloquially called space raptors, are the genetically altered descendents of Troodon. An extinct race called the Builders, or Architects, visited Earth during the last decades of the reign of dinosaurs, and made off with a large population of Troodon formosus specimens, which were determined to be the most likely sapient candidates at the time. When they eventually died out, the Builders left behind a number of modified organisms, many of which failed and themselves perished, either from uncontrolled infighting or long-term genetic non-viability.

Astrosaurus was one of the rare success stories. Standing between 4 and 5 feet tall and reaching usually twice as long with the tail, they are feathered non-avian theropods with dextrous hands and a large brain. They have no visible ears but have strong binocular vision; their combination of enlarged cranial cavity and ocular-oriented senses had left them with a rather human-like snout. Their soft proto-feathers come in every shade imaginable, tending towards gaudy shades on their long ruffs and more neutral bases along their bodies. Stripes, spots, blotches and banding are fairly common and tend to run in families.