Compare and contrast the nectridians with modern tetrapods. what was the lifestyle of a nectridian?....?

Nectridians were amphibians with an aquatic lifestyle. Modern tetrapods (amphibians, reptiles, birds and mammals) are usually less aquatic. However, whales, some salamanders such as the congo eels (genus Amphiuma), some frogs (e.g. the Surinam toad and African clawed frogs), extinct marine reptiles like ichthyosaurs are just as aquatic as any ancient aquatic amphibian.