Investigating the Presence of Haringtonhippus in the American Falls Formation of the Snake River Plain, Idaho, USA
Faculty Mentor Information
Dr. Brandon Peecook, Idaho State University
Presentation Date
7-16-2026
Abstract
During the Ice Age, there were two types of horses in North America: stout-legged and stilt-legged. In 2017, ancient DNA analysis put the stout-legged horses into the genus Equus and the stilt-legged horses into the genus Haringtonhippus. Since its discovery, Haringtonhippus has been found across Western North America. This horse has not been described in Idaho, despite the state’s abundance of Ice Age horse specimens.
Due to its history of being synonymized with Equus, unidentified Haringtonhippus specimens likely exist in Idaho museum collections.
This study aims to refine the knowledge of the range of Haringtonhippus and Equus. Here, we use linear morphometric methods to quantify subtle differences in horse leg shape (N=65) at the IMNH. Principal component analysis and linear discriminant analysis were performed, incorporating a priori data from published records.
All measured IMNH species are grouped in Equus morphospace. None of the specimens can be confidently assigned to Haringtonhippus.
If Idaho has evidence for only Equus, this would make it a unique region in western North America where Haringtonhippus is not occupying the same habitat as Equus. This difference in distribution illustrates how two morphologically similar populations still respond to their environment in different ways.
Investigating the Presence of Haringtonhippus in the American Falls Formation of the Snake River Plain, Idaho, USA
During the Ice Age, there were two types of horses in North America: stout-legged and stilt-legged. In 2017, ancient DNA analysis put the stout-legged horses into the genus Equus and the stilt-legged horses into the genus Haringtonhippus. Since its discovery, Haringtonhippus has been found across Western North America. This horse has not been described in Idaho, despite the state’s abundance of Ice Age horse specimens.
Due to its history of being synonymized with Equus, unidentified Haringtonhippus specimens likely exist in Idaho museum collections.
This study aims to refine the knowledge of the range of Haringtonhippus and Equus. Here, we use linear morphometric methods to quantify subtle differences in horse leg shape (N=65) at the IMNH. Principal component analysis and linear discriminant analysis were performed, incorporating a priori data from published records.
All measured IMNH species are grouped in Equus morphospace. None of the specimens can be confidently assigned to Haringtonhippus.
If Idaho has evidence for only Equus, this would make it a unique region in western North America where Haringtonhippus is not occupying the same habitat as Equus. This difference in distribution illustrates how two morphologically similar populations still respond to their environment in different ways.