Cardiodon (meaning "heart tooth", in reference to the shape) was a genus of sauropod dinosaur, based on a tooth from the late Bathonian-age Middle Jurassic Forest Marble Formation of Wiltshire, England. Historically, it is very obscure and usually referred to Cetiosaurus, but recent analyses suggest that it is a distinct genus, and possibly related to Turiasaurus.
History and TaxonomyEdit
Richard Owen named the genus for a now-lost tooth found near Bradford-on-Avon, but did not assign it a species name at the time; a few years later, he added the species name. Within a few decades, he and others were viewing it 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.
In 2003, Paul Upchurch and John Martin, reviewing Cetiosaurus, found that there is little evidence to assign the C. oxoniensis teeth to the skeleton, and the "C. oxoniensis" teeth differ from the Cardiodon teeth (Cardiodon teeth are convex facing the tongue); therefore, they supported Cardiodon being retained as its own genus. Upchurch et al. (2004) repeated this assessment, and found that though the teeth have no known autapomorphies, they are those of an eusauropod. More recently, Royo-Torres et al. (2006), in their description of Turiasaurus, pointed out Cardiodon as a possible relative to their new, giant sauropod.
As a sauropod, Cardiodon would have been a large, quadrupedal herbivore, but because of the scanty remains, much more cannot be said.