Alvarezsauridae is an enigmatic clade of theropod dinosaurs. They were initially thought to be the earliest non-flying birds, but now they are known as theropod dinosaurs, closely related to Ornithomimids.
The members of this clade survived during the Late Cretaceous era, and their bony remains have been found in North and South America, Asia, and especially Europe.
Characteristics[]
Alvarezsaurids were small, bipedal dinosaurs, with very long legs well-suited for speed-running, a relatively short tail, a long, S-shaped neck, in top of wich standed a small head with large eyes, and one unusual characteristic: all Alvarezsaurids had 2 fingers: one very small, almost undetectable, and the other much larger, with a sharp claw at the end of it. It is actually thought that these dinosaurs used the larger finger to catch their food, that consisted in colonial insects such as ants and termits.
Alvarezsauroid's covering is generally unknown, althought the fossil of Shuvuuia deserti actually shows impressions of proto-feathers. Furthermore these proto-feathers seem to be rich in beta-keratine, a protein very common in modern-day feathers.
Classification[]
- Alvarezsaurus calvoi;
- Patagonykinae:
- Bonapartenykus ultimus;
- Patagonykus puertai;
- Parvicursorinae:
- Parvicursor remotus;
- Ceratonykini:
- Albinykus baatar;
- Ceratonykus oculatus;
- Xixianykus zhangi;
- Mononykini:
- Albertonykus borealis;
- Linhenykus monodactylus;
- Mononykus olecranus;
- Shuvuuia deserti;
- Patagonykinae:
Uncertain placement:[]
- Bradycneme draculae (more likely a troodontid);
- Heptasteornis andrewsi;
- rapator ( possibly a allosaurid )
- Achillesaurus manazzonei