Review of horses in Paleoindian sites of the Americas.

The research article talks about the different species of horses that existed in North and South America during the Paleoindian era, about 13,000 to 8,000 years ago, acknowledging that at least eight Equus ecospecies were found in North America and several others in South America living in a range of habitats.

Study of Ancient Horse Species

The main focus of the paper is an in-depth analysis of the different horse species that coexisted with early human settlements in North and South America:

• The researchers conducted morphological character studies, examining the physical structuring of over eight recognised Equus ecospecies in North America.
• The study revealed existence of Equus species that had evolved into separate ecospecies, with specific adaptations and characteristics unique to their habitats.

Horse Species in South America

Beyond North America, the paper also analyzes horse ecospecies evolution in South America:

• At least four Equus ecospecies were identified to have existed in South America at that time.
• Hippidion, another genus of horses, had 1 ecospecies, whereas Onohippidium had three distinct, geographically separated ecospecies.

Temporal and Geographic Ranges

In addition to exploring the different horse ecospecies, the paper lays emphasis on the geological variation and time period:

• The identified ecospecies are known to have existed in the time period from approximately 13,000 to 8,000 years ago, referred to as the Paleoindian period.
• The horse species lived in a wide variety of climates and habitats, from tropical environments to colder ecotopes in high Andean and Patagonian areas.

Overall, the paper provides a comprehensive review and examination of the diversity and range of horse species that existed in the Americas during the Paleoindian period.