Paleocene hyracothere from polecat bench formation, wyoming.

The research article discusses the discovery of a prehistoric horse fossil, specifically the lower jaw of an Eohippus (also known as Hyracotherium), from the late Paleocene epoch discovered in Wyoming. This discovery pushes back the timeline for when such creatures are known to have existed and suggests that the perissodactyls (odd-toed ungulates) may have originated before previously thought.

Discovery of the Fossil

• The research article pertains to the discovery of the fossil of a lower jaw of an Eohippus, also known as a ‘dawn horse’, typically recognised as the earliest horse ancestor.
• This fossil was recovered from late Paleocene strata in Wyoming, which dates back approximately 56 to 66 million years, effectively extending the known geological record of horse fossils.
• The fossil suggests that the perissodactyls, or odd-toed ungulates (a group of large mammals including horses, rhinoceroses, and tapirs), may have had origins earlier than what was previously conjectured.

Implications of the Discovery

• The finding of this fossil in conjunction with equid teeth, possibly also of late Paleocene age, from Baja California indicates that early perissodactyls had a widespread presence across the North American continent before the beginning of the Eocene epoch, which followed the Paleocene.
• This stands to alter existing perceptions about the distribution and diversification of early mammals.

Additional Findings in Wyoming

• The late Paleocene and early Eocene deposits in northwestern Wyoming have provided a plethora of unusual vertebrate fossils and ‘first or earliest occurrences’, necessitating revisions of the understanding of intercontinental and intrathercontinental dispersal patterns of the vertebrate groups involved.
• These findings suggest that the area may have been a crucial hub in the early evolution and dispersion of various mammalian groups, including the perissodactyls.