Interesting Anatomy of Small Dinosaurs

The number of specimens and the preservation of those specimens is enough to make a few concrete observations about the anatomy of Alvarezsaurus that we can discuss today. The vertebrae, especially the caudal vertebrae, are well known and the descriptions of the vertebrae are highly detailed, if anyone is interested in the vertebrae; my interest in vertebrae is waning these days. More interesting and unique is the known anatomy of the shoulders and ankles of Alvarezsaurus. The scapula, for example, is smaller, relatively, than other members of the family. It is also curved caudally as one traces it dorsally behind the shoulder itself. The ankle is also special within the family as it does not consist of a fused calcaneus and astragalus. An unfused ankle and a small, curved scapula are apparently basal within the alvarezsauridae, as Alvarezsaurus is often described as a primitive form within the family that bears its name. These features are hard to see in this mounted skeleton, but they are there.