Lemur of mouse lemurs, the gray mouse lemur ("M. murinus"), golden-brown mouse lemur ("M. ravelobensis"), and Goodman's mouse lemur ("M. lehilahytsara") were considered the same species until recently, when genetic tests identified them as cryptic species. The lemur dentition is heterodont (having multiple tooth morphologies) and derives from an ancestral primate permanent dentition of . Indriids, sportive lemurs, the aye-aye, and the extinct sloth lemurs, monkey lemurs, and koala lemurs have reduced dentitions, having lost incisors, canines, or premolars. The ancestral deciduous dentition is , but young indriids, aye-ayes, koala lemurs, sloth lemurs, and probably monkey lemurs have fewer deciduous teeth.
I Should Have Known Better film, and it appears on the soundtrack. Capitol Records released "Something New" a month later with songs from the UK version of "A Hard Day's Night" that were not used in the film. The songs were also later released by Capitol on the "Hey Jude" compilation album in 1970. "I Should Have Known Better" was released as a single in a number of continental European countries, including Norway, where it reached number 1, and West Germany, where it reached number 6. In Sweden, the song topped the Kvällstoppen Chart for four weeks. The song is performed in the train compartment