Which feature is shared by crocodile with all mammals?

Similarities between crocodiles and mammals:

1. Crocodiles and mammals both have four-chambered hearts.
2. Crocodile belongs to the class Reptilia, all the reptiles possess three-chambered heart except the crocodile
3. Crocodiles, like alligators, are members of the Crocodylia order, which also includes birds and long-extinct dinosaurs.
4. Presence of hair all over the body, mammary gland, and four-chambered heart makes mammals distinct from reptiles.