Question

geologists discovered fossil evidence of mesohippus, an ancestor of the modern horse. mesohippus lived in north america about 40 million years ago. mesohippus was about two feet tall, ran on hooves with three toes, and had large, grinding teeth. what statement is best supported by the fossil evidence? a ancient horses were once carnivores. b horses have evolved over the last 40 million years. c horses migrated from south america into north america. d modern - day horses share a common ancestor with all mammals.

Explanation:

• Option A: Mesohippus had grinding teeth, suggesting herbivory, not carnivory, so A is incorrect.
• Option B: Mesohippus is an ancestor of modern horses, lived 40 million years ago, and has different features (e.g., three - toed hooves, smaller size) than modern horses. This supports that horses have evolved over 40 million years.
• Option C: The fossil evidence is from North America and there's no info about migration from South America, so C is incorrect.
• Option D: The evidence only relates to horse evolution, not a common ancestor with all mammals, so D is incorrect.

Answer:

B. Horses have evolved over the last 40 million years.