Dinosaur Egg - Classification

Classification

The microscopic structure of dinosaur eggshell consists of a series of basic vertical units that grow from particular sites on the surface of the shell. The organisation of these units determines the classification scheme, being either spherulitic or prismatic:

• Spherulitic egg shells show spherical patterns in the crystalline structure, and they are seen in sauropods and hadrosaurs.
• Prismatic egg shells grow into spherical crystals only in the lower portion of the shell, while crystals in the upper portion are prisms.
• Ornithoid eggs (also seen in birds) are generally laid by theropods. In this type only the very bottom part of the shell exists as separate or discrete units (mammilae). The upper and mid-portions of the shell consist of a mass of biocrystalline material with a spongy (squamatic) ultrastructure, that comprises a homogeneous layer.