Which group of plants common during the triassic period had seeds lacking a protective outer coat?

The most dominant form of plants found in Triassic Era was Gymnosperms. They lack a protective covering on seed and did not produce flower. The outer coating of seed is absent in Gymnosperms. There were no angiosperm in that era and the dominant form was angiosperm only. This was because of the climatic conditions at that time that the survival of any other plants other than gymnosperm was not possible.