From Discover Magazine: (hat tip Floyd)

Three tiny creatures from the Triassic period are the oldest ever to be
discovered preserved in amber – about 100 million years older than any
other amber arthropod ever collected…. 

… But even though arthropods are more than 400 million years old, until
now the oldest record of the animals in amber dates to about 130
million years. The newly-discovered arthropods take that date back to
230 million years.

About 70,000 of the amber droplets, most between two and six millimeters long, were screened for inclusions…

Two of the specimens are new species of mites, named Triasacarus fedelei and Ampezzoa triassica.