Complex sentence: Three years later, he earned his MA in Linguistics from the University of New Mexico and, in 1998, he graduated with a PhD in Linguistics from Stanford University, where he was a student of Penelope Eckert, Eve Clark, and Elizabeth Traugott.
Split into simpler sentences: Three years later, he earned his MA in Linguistics from the University of New Mexico. In 1998, he graduated with a PhD in Linguistics from Stanford University, where he was a student of Penelope Eckert, Eve Clark, and Elizabeth Traugott.