Tinodon

Tinodon is an extinct genus of mammal. First described by the paleontologist Othniel Charles Marsh, it contains two recognized species: Tinodon bellus and T. micron. It is known from jaw and dental remains. Its taxonomic placement within the mammalian lineage remains uncertain, having been variously placed within and outside of the crown group Mammalia. It lived from the Late Jurassic to the Early Cretaceous, found in both North America and Europe. Its known habitats are believed to have ranged from semi-arid to arid.

==History of discovery== The genus Tinodon was described by American paleontologist Othniel Charles Marsh in 1879, from remains found in the "Jurassic beds of the Rocky Mountains" (now known as the Morrison Formation). In 1887, he assigned the genus to the new family Tinodontidae. Marsh identified four species of Tinodon: T. bellus (the type species), T. ferox, T. robustus, and T. lepidus. The species T. ferox and T. robustus have since been moved to the genus Priacodon, while T. lepidus has been treated as a synonym of T. bellus. An additional species was described from teeth from England's Purbeck Group in 2000 by French paleontologist Denise Sigogneau-Russell and British geologist Paul Ensom. It was named T. micron. Another species was suggested by American paleontologists George Engelmann and George Callison in 1998, but it was left in open nomenclature. A tooth found by German paleontologist Georg Krusat in 1969 at the Lourinhã Formation in Portugal has been tentatively assigned to Tinodon, but the identity of the specimen remains uncertain.