Dinosaur tooth

Dinosaur teeth have been studied since 1822 when Mary Ann Mantell (1795-1869) and her husband Dr Gideon Algernon Mantell (1790-1852) discovered an Iguanodon tooth in Sussex in England. Unlike mammal teeth, individual dinosaur teeth are generally not considered by paleontologists to be diagnostic to the genus or species level for unknown taxa, due morphological convergence and variability between teeth. and many historically named tooth taxa like Paronychodon and Richardoestesia are today considered nomina dubia, and are used as form taxa to refer to isolated teeth from other localities displaced considerably in time and space from the type specimens. However, it is possible to refer isolated teeth to known taxa provided that the tooth morphology is known and the teeth originate from a similar time and place. Some of the most important anatomical information about dinosaur teeth is collected from polished, microscopically thin sections (histology), including the types of dental tissues present, tooth wear, tooth replacement patterns, how the teeth are attached, and the frequency of replacement. The actual material comprising a dinosaur tooth is not very different to teeth in modern animals. Most significant differences are in how the teeth fit together and continually regrew, with some examples shedding old teeth and others reabsorbing old teeth as they would grind down under chewing throughout a dinosaurs life. The use of histology in paleontology has traditionally been more focused on examining long bones such as the femur or the humerus. Previous work on long bone histology revealed differences in the growth patterns of polar dinosaurs, identified a case of dwarfism in Europasaurus, reconstructed the life history of Dysalotosaurus by examining multiple specimens of different ontogenetic stages, and suggested that Psittacosaurus underwent a postural change from a quadruped to biped as it matured. By contrast, dental histology has not been looked at in great detail in dinosaurs until more recently and there has been an increase in interest in this particular sub-field.