Which feature is shared by a crocodile with all mammals?

Hint: Crocodiles, also known as true crocodiles, are large semi aquatic reptiles found in the tropics of Africa, Asia, the Americas, and Australia. All extant members of the order Crocodilia, which includes alligators and caimans (family Alligatoridae), gharials and false gharials (family Gavialidae), and all crocodiles (family Crocodilia), are referred to as crocodiles.

Complete answer:
Mammary glands, which produce milk for feeding (nursing) their young in females, a neocortex (a region of the brain), fur or hair, and three middle ear bones distinguish mammals from other vertebrates.
These characteristics set them apart from reptiles and birds, from which they diverged over 300 million years ago in the Carboniferous. There are approximately 6,400 extant mammalian species. Rodents, bats, and Eulipotyphla are the three largest orders (hedgehogs, moles, shrews, and others).
The following feature is shared by a crocodile with all mammals:
1. All mammals, including crocodiles, have a four-chambered heart.
2. A crocodile is a large amphibious reptile that lives in water.
3. Except for crocodiles, all reptiles have a three-chambered heart.
4. It is an ambush predator that lives mostly in large tropical rivers.
5. Crocodiles, like alligators, are members of the Crocodylia order, which also includes birds and long-extinct dinosaurs.
6. Crocodiles do not sweat, so they release heat through their mouths.

Note:
The majority of mammals are intelligent, with some having large brains, self-awareness, and the ability to use tools. Mammals use a variety of methods to communicate and vocalize, including ultrasound, scent-marking, alarm signals, singing, and echolocation. Mammals can form fission-fusion societies, harems, and hierarchies, but they also can be solitary and territorial. The majority of mammals are polygynous.