The flowers above/below were discovered deep within a mine in the Dominican Republic. Thanks to the now-extinct resin-producing tree Hymenaea protera, amber-preserved fossils are a big industry in the country—discoveries of ancient specimens are common—but the fossils here represent the earliest known examples of modern flowering plants known as asterids, a group consisting of some 80,000 species.
This makes the fossils among the oldest known kin to common modern day plants such as sunflowers, tomatoes, tobacco, sweet potatoes, and common herbs like mint and basil. According to a paper published today in Nature Plants describing the discovery of the new-ancient flowers, they are between 15 and 45 million years old: "the first fossil neotropical flowers found in amber from a representative of the asterids." The new species is officially known as Strychnos electri—a member of the Strychnos genus, which also includes the Strychnine tree from which the namesake poison is extracted.
S. electri offers a new piece of the persistent puzzle that is the neotropical forest of the mid-Tertiary, a period of geological history in which the climate changed dramatically as the planet's then-supercontinents began to evolve into what we see today. The flowers would have appeared well before the North and South American continents had fused together at the Panama land bridge.
As the authors of the study note, there are likely many more discoveries from that era to come, including those still existing within present day Caribbean forests. S. electri is almost certainly long-extinct.