Dinasian

The Dinasians were an ancient warp-capable humanoid civilization native to the planet Dinasia. By the 24th century, the Dinasians were extinct. 

Biology
The Dinasians probably evolved from a creature with both reptilian and mammalian traits. They had an elongated torso and long arms, and also big reptilian-like eyes. Their heads were covered by a long structure resembling a hollow crest. 

History
Approximately 200,000 years ago, the Dinasians were suffering from a terrible plague in their homeworld. Seeking for help, the Dinasians asked for the Iconians' assistance, who by that period had an extensive experience with genetic and medical technology. However, despite the Iconian's help, the Dinasians stated they neeeded the means to take care of themselves rather than continue to survive on Iconian medical supplies. An analisys made by the Iconians of that period about the Dinasian's biomedical ethics, however, indicated that at their "primitive" level of development they had an 84.6 percent chance of doing themselves harm with genetic engineering and a 74.2 percent chance of using it for biological warfare. For that reason, the Iconians decide to continue to assist the Dinasians with medical supplies but withhold other medical technology.

Not accepting the Iconian's decision, however, the Dinasians, alongside with several other races with similar claims, as the Iccobar, planned an invasion of the Iconian homeworld in order to get access to their technologies. The invasion took place as planned, resulting in the orbital bombardment of Iconia and the almost complete extinction of the Iconian race. 

Language
By the 24th century, the discovery of Iconia by the USS Enterprise-D revealed close ties between the Dinasian and Iconian languages. This could be explained by the hypothesis that some Iconian words were incorporated in the Dinasian language after they took possession of the Iconian's technology, thus needing to learn the Iconian language in order to use these technologies.

Another explanation is that some Iconians were able to escape their homeworld's destruction and ended up on Dinasia, where they settled themselves and slowly merged into the Dinasian society.