Grotesque dolphins were much used in the Regency and Victorian eras, reflecting the decorative taste of the time. The architect, Amon Wilds and his son, used such motifs, including the ammonite motif, on their buildings and structures in Brighton (West Sussex) in particular. The front of the elegant Wilds designed home of Mantell in West Sussex (Mantell discovered the first dinosaur fossil) is decorated with stylised ammonites.
The Victoria Fountain in Brighton (inaugurated on 25 May 1846, for the twenty-seventh birthday of Queen Victoria) was very possibly the inspiration behind Sowerby's later Diving Dolphins bowl (written about and illustrated in my books based on original research done by Angela Thistlewood in 1995). It has three writhing dolphins as feet with a bowl above (for the fountain).
Short answer on what could be a lengthy topic (but with no time for more right now).
Glen