Paleontology.

Paleontology (παλαιοντολογία) is the study about life on the Earth, which existed before Holocene epoch. This word came from the Greek language παλαιός, palaios  "old", ὄν, on "creature", and λόγος, logos "study".

Science about ancient creatures has similar features with other studies. Biology, geology, and archaeology are related sciences to paleontology. 

Paleontologists are studying the history of life on our planet. Ancient fossils can tell a lot about animals and their lives.

Also, scientists study climate of that periods. Billions and millions years ago the weather was different. Ice age changed life of animals.

Paleontology helps to understand the life of dinosaurs. They lived on the Earth many years ago. Then the dinosaurs died.

This science explains evolution. Different animals have different ancestors. They could be of other size and live in other places.

Plants at that time were different, too.

Science about ancient animals studies in colleges and universities.

Source of image:

https://www.shutterstock.com/es/image-vector/cartoon-paleontology-kids-working-on-excavation-1433866022

Source of image:

https://www.shutterstock.com/es/image-vector/archaeologist-near-archaeology-items-dig-equipment-1513927937

Source of image:

https://www.shutterstock.com/es/image-vector/archaeologists-paleontology-scientists-working-on-excavations-1307853316

Source of image:

https://www.shutterstock.com/es/image-vector/cute-man-archaeologists-cartoon-searching-fossil-601596866

Source of image:

https://www.shutterstock.com/es/image-photo/background-ammonite-shells-concretions-other-paleontological-1835368402