Were there ants when there were dinosaurs?

Yes.

Ant is a very ancient insect. Its origin can be traced back to the Cretaceous period 130 million years ago, the same era as the dinosaurs. The ancestors of ants are wasps that migrated to the ground to live in colonies. They were very rare in the age of the dinosaurs, but gradually became common. There are many types of ants, and there are at least 600 species in China.

Scientists have discovered that the subfamily Myrmidinae, which first appeared between the late Jurassic and the early Cretaceous, may be the oldest of all ants, pushing the appearance of ants back to at least 40 million years . Around the middle and late Cretaceous, angiosperms in the plant kingdom rapidly expanded and differentiated, covering most of the land on the earth. At the same time, the ant family suddenly flourished, the number of new species increased threefold, and various genera and species of modern ants were basically formed.

The discovery was published in the journal Science. Coley Morrow and others from Harvard University said in the paper that they analyzed the genetic information of 19 subfamilies and 139 species of existing ants, and reconstructed the "kinship relationship" of various modern ants based on the "clock" of genetic changes. ” and speculate on their evolutionary rules. The researchers used the fossil record to calibrate the evolutionary rate of ant DNA and concluded that today's ants emerged approximately 140 to 168 million years ago. But ant diversity only began to increase 100 million years ago, shortly after the emergence of flowering plants.

Extended material:

The Cretaceous Period (English: Cretaceous Period) is the last period of the Mesozoic Era in geological time. It started 145 million years ago and ended 66 million years ago? After 79 million years. It is the longest stage of the Phanerozoic Eon.

During this period, the continents were separated by oceans, and the earth became warm and dry. During the period when the largest dinosaurs appeared, many new dinosaur species began to appear. Dinosaurs still ruled the land, pterosaurs glided in the sky, and giant marine reptiles ruled the shallow seas. The first snakes, moths, and bees also appeared, as did many new small mammals. Angiosperms also appeared during this period.

Reference: Baidu Encyclopedia - Myrmidinae