Atoposauridae

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Atoposauridae is an extinct family of small, crocodile‑like reptiles that lived in Eurasia from the Middle Jurassic to the Late Cretaceous. They were small in size and had different tooth types (heterodont), which suggests a varied diet. They likely spent time both on land and in shallow water, feeding on small prey such as fish, insects, and possibly small mammals.

Fossil record highlights:
- The oldest fossils come from the Middle Jurassic of Britain.
- Most are known from the Late Jurassic to Early Cretaceous in France, Portugal, and southern Germany (Bavaria).
- The genus Aprosuchus extends the lineage to the end of the Cretaceous in Europe.

What they are and where they fit:
- Atoposauridae is part of Neosuchia, a group of crocodile‑like reptiles.
- Scientists disagree about their exact position in the crocodile family tree. Some studies (2016) suggest atoposaurids were an early, somewhat scattered group (paraphyletic) with only certain genera (Alligatorium, Alligatorellus, Atoposaurus) considered true atoposaurids. Other studies (2017, 2024) support a single, natural group (monophyletic) that sits as a sister group to Paralligatoridae within Eusuchia (the larger group that includes modern crocodilians).

Genera:
- Alligatorellus, Alligatorium, Aprosuchus, Atoposaurus, Knoetschkesuchus
- Other possible members mentioned in the literature include Montsecosuchus, Ogresuchus, Theriosuchus, and Varanosuchus

In short, atoposaurids were small, early crocodile relatives with diverse teeth and lifestyles, known from much of Europe from the Middle Jurassic to the end of the Cretaceous, with ongoing scientific debate about their exact evolutionary relationships.