Fossils of animals the size of goats were dated at 5 million years old. similarly, fossils of larger animals were dated at 3 million years old. both animals were similar in body structure to today's horses. using these data, which inference can scientists make? a the animals were probably ancestors of today's horses. b the animals had no relationship to one another. c today's horses and these animals probably lived together at some time in the past d today's horses are faster than these animals were.