Within a few decades, he and others were viewing "Cardiodon" as a possible synonym of his most well-known sauropod genus, "Cetiosaurus". Richard Lydekker formalized this view in a roundabout way in 1890, by assigning "Cetiosaurus oxoniensis" to "Cardiodon" on the basis of teeth from Oxfordshire associated with a skeleton of "C. oxoniensis". He also added a second tooth (BMNH R1527) from the Great Oolite near Cirencester, Gloucestershire. More typically, "Cardiodon" has been assigned to "Cetiosaurus", sometimes as a separate species "Cetiosaurus rugulosus", in spite of its priority.