Aldrich's paleontological hobby became his career in later life, when Eugene Allen Smith appointed him as Curator of Paleontology of the Alabama Museum of Natural History. He donated large collections of Southeastern fossils, many from sites that are no longer exposed today. Under Herbert Huntington Smith and Daisy Smith, who were hired in 1909, the Museum continued his species-based cataloging system for fossils and Aldrich continued to write short articles on Tertiary mollusks.