Some cool animals that are extinct images:
Frozen In Rock
Image by tarotastic
"Trilobites are extinct arthropods in the class Trilobita. They appeared in the Cambrian era and flourished throughout the lower Palaeozoic before slowly declining to extinction. The last of the trilobites disappeared in the mass extinction at the end of the Permian. Trilobites are well-known, possibly the second most famous fossil group after the dinosaurs, and are the most diverse group of animal species preserved in the fossil record, consisting of eight, possibly nine, orders and over 15,000 species. Most were simple, small marine animals that filtered mud to obtain food." - Wikipedia
This specimen is about 2cm long.
Thylacines 04 (Wiki)
Image by smiteme
Image via Wiki and is part of the public domain.
Caption: "The last known Thylacine photographed at Hobart (formerly Beaumaris) Zoo in 1933. A scrotal sac is not visible in this or any other of the photos or film taken, leading to the supposition that "Benjamin" was a female, but the existence of a scrotal pouch in the Thylacine makes it impossible to be certain."
(See also: Portrait of Benjamin, a Thylacine. on easyvegan.info.)
Guinea pigs huddling up - Zoo Hannover
Image by Thorsten Becker
The Guinea pig (also commonly called the cavy after its scientific name) is a species of rodent belonging to the family Caviidae and the genus Cavia. Despite their common name, these animals are not pigs, nor do they come from Guinea. They are native to the Andes, and while now extinct in the wild, they are closely related to several species that are commonly found in the grassy plains and plateaus of the region. The guinea pig plays an important role in the folk culture of many Indigenous South American groups, especially as a food source, but also in folk medicine and in community religious ceremonies. Since the 1960s, efforts have been made to increase consumption of the animal outside South America.
In Western societies, the guinea pig has enjoyed widespread popularity as a household pet since its introduction by European traders in the 16th century. Their docile nature, their responsiveness to handling and feeding, and the relative ease of caring for them, continue to make the guinea pig a popular pet. Organizations devoted to competitive breeding of guinea pigs have been formed worldwide, and many specialized breeds of guinea pig, with varying coat colors and compositions, are cultivated by breeders.