The rhinoceros sculpture in front of the School of the Museum of Fines Arts is a dedication to Boston sculptor and SMFA Alum, Katharine Lane Weems. In fact it is a copy of her two Indian Rhinoceroses, Bessie and Victoria, that sit in front of Harvard's Department of Molecular and Cellular Biology. Weems (1899-1989) was born into a family of culturati--her father was once the president of the MFA--and she was known for her animal sculptures.
The National Museum of Wildlife Art of the United States has a quote from Weems. When she was asked why she chose animals as her primary subject matter as opposed to people, Weems commented, "When you're doing a human figure you're always working on the same fundamental chassis; but with animals the variation in composition is infinite; an animal is forever in movement, in different, unconscious grace. And finally, you never have the relatives to contend with!"
Take a look at some photos of Katharine at work.