It is noteworthy to mention that Weller supervised Grace Anne Stewart, the first Canadian female to earn a B.A.

Weller's professional career was devoted largely to Paleozoic faunas of the Mississippi Valley, with particular emphasis on Mississippian strata.

Other research was made possible by Weller's long association with state and national geological surveys.

His most important connection was with the Illinois State Geological Survey from 1906 to 1927, during which period he acted as the principal consultant on paleontological problems and produced a number of significant maps and stratigraphic reports.

[2][4] From 1919 until his death, in addition to his professorship, he was the director of the Walker Museum at the University of Chicago.