@article {1142391, title = {Evolution of the mammalian fauces region and the origin of suckling}, journal = {Journal of Mammalian Evolution}, year = {Submitted}, note = {See Science Magazine{\textquoteright}s take on our research: http://science.sciencemag.org/content/361/6399/213}, abstract = {Suckling in therian mammals requires synchronous activity in the tensor veli palatini, palatoglossus,mylohyoideusand intrinsic tongue muscles that close the fauces. These muscles draw the dorsal surface of the tongue against a tensed soft palate to form a seal between the oral cavity and oropharynx. Depressing the tongue in front of the seal induces negative pressure and draws milk into the oral cavity.To trace the origin offauces region in mammals,we studied serial sections of a pouch young marsupialandCT scans of non-mammalian cynodonts, ictidosaurs, mammaliaforms, and extant mammals.In Late Triassic ictidosaurs (Brasilitherium) and mammaliaforms, the origin of a medial slip of the reptilian posterior pterygoideus migrated to the lateral surface of the pterygopalatine boss that supported the lateral edge of a non-muscular soft palate.Suckling arose in early mammals after fibers of this slip migrated into the soft palate to form the tensor veli palatini, and the palatoglossus separated from the pharyngeal constrictors. The added stress on the pterygopalatine boss led to the addition of a hamulus.Once the transverse process of the pterygoid was lost, the lateral posterior pterygoideus differentiated to form the medial pterygoid.Monotreme ancestorsmodified the fauces regionto break down invertebrates between keratinized padsontheposteriortongue andundertheventral surface of a long palatine.Theylost the tensor veli palatini and palatoglossus andlack the ability to suckle.}, author = {Crompton, Alfred W. and Musinsky, Catherine and Bonaparte, Jos{\'e} F. and Bhullar, Bhart-Anjan and Owerkowicz, Tomasz} }