A scientist is studying three different layers of sedimentary rock to learn how a particular mammal species has changed over time. In the rock layer that is closest to the Earth's surface, fossilized individuals of this species have hooves on both their front feet and their back feet. In the layer below, fossilized individuals have three padded toes on both their front feet and their back feet. In the bottom layer, fossilized individuals have four padded toes on their front feet and three padded toes on their back feet. Based on this information, individuals of this species today most likely have?