Theriiformes

{{Short description|Clade of mammals}}

{{Automatic taxobox

| fossil_range = {{Geological range/linked|Middle Jurassic|Recent}}

| image = Ptilodus skull.jpg

| image_caption = Skull of the multituberculate Ptilodus (Allotheria)

| image2 = Maotherium.jpg

| image2_caption = Skeleton of Maotherium (Trechnotheria)

| taxon = Theriiformes

| authority = Rowe, 1988

| subdivision_ranks = Subgroups

| subdivision = * {{extinct}}Allotheria

• {{extinct}}Tinodontidae
• Trechnotheria

}}

Theriiformes is a clade of mammals. The term was coined by Timothy B. Rowe in his doctoral dissertation, and is defined as the clade formed by the most recent common ancestor of multituberculates (which form part of the broader group Allotheria, along with Gondwanatheria and likely all/part of Haramiyida) and Theria (the group containing marsupials and placental mammals).{{Cite book |url=http://dx.doi.org/10.1515/9783110341553 |title=Mammalian Evolution, Diversity and Systematics |date=2018-10-22 |publisher=De Gruyter |isbn=978-3-11-034155-3 |editor-last=Zachos |editor-first=Frank |editor-last2=Asher |editor-first2=Robert}} Mammals more closely related to therians than to multituberculates are included in the clade Trechnotheria. As multituberculates are usually considered more closely related to therians than monotremes are (though some studies have recovered allotherians as less closely related to therians than monotremes are, placing them outside of crown group Mammalia{{Cite journal |last=Mao |first=Fangyuan |last2=Li |first2=Zhiyu |last3=Wang |first3=Zhili |last4=Zhang |first4=Chi |last5=Rich |first5=Thomas |last6=Vickers-Rich |first6=Patricia |last7=Meng |first7=Jin |date=2024-04-18 |title=Jurassic shuotheriids show earliest dental diversification of mammaliaforms |url=https://www.nature.com/articles/s41586-024-07258-7 |journal=Nature |language=en |volume=628 |issue=8008 |pages=569–575 |doi=10.1038/s41586-024-07258-7 |issn=0028-0836|url-access=subscription }}) it is considered to be a subgroup of the mammalian crown group.{{Cite journal |last=Macrini |first=Thomas E. |last2=Rougier |first2=Guillermo W. |last3=Rowe |first3=Timothy |date=July 2007 |title=Description of a Cranial Endocast from the Fossil MammalVincelestes neuquenianus (Theriiformes) and its Relevance to the Evolution of Endocranial Characters in Therians |url=https://onlinelibrary.wiley.com/doi/10.1002/ar.20551 |journal=The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology |language=en |volume=290 |issue=7 |pages=875–892 |doi=10.1002/ar.20551|url-access=subscription }}

The cladogram below follows Luo et al. (2016):

{{Clade|style=font-size:85%; line-height:85%

|label1=Mammalia

|1={{Clade

|1=Australosphenida

|label2=Theriimorpha

|2={{Clade

|1=Fruitafossor

|2={{Clade

|1=Eutriconodonta

|label2=Theriiformes

|2={{Clade

|1={{Clade

|1=Gondwanatheria

|2=Multituberculata

}}

|label2=Trechnotheria

|2={{Clade

|1=Spalacotherioidea

|label2=Cladotheria

|2={{Clade

|1=Dryolestoidea

|2=Theria

}} }} }} }} }} }} }}