Question

1. what is the biggest change in skull anatomy that occurred from the dawn horse to the modern horse?

Explanation:

The dawn horse (Eohippus) had a small skull with a short snout and small brain case. Over evolutionary time, the skull of the modern horse became much larger, with a significantly elongated snout to accommodate high-crowned grazing teeth, and an expanded brain case to house a larger, more complex brain adapted for advanced sensory and cognitive functions. The most prominent and impactful change is the overall increase in skull size paired with the elongation of the facial region (snout) and enlargement of the brain cavity.

Answer:

The biggest change is the significant increase in overall skull size, along with a dramatic elongation of the snout (facial region) to fit specialized grazing teeth, and an expanded brain case that houses a larger, more complex brain compared to the small, short-snouted skull of the dawn horse (Eohippus).