Simplify the following text for a Grade 7 native English-speaking person.
Original: By the 18th century two breeds had been developed for hunting hare and rabbit : the Southern Hound and the North Country Beagle ( or Northern Hound ) . The Southern Hound , a tall , heavy dog with a square head , and long , soft ears , was common from south of the River Trent and probably closely related to the Talbot Hound .
Simplified: They are extinct now , but once they had made the Southern Hound more popular , which helped the Southern Hound descend to the Beagle .