View source for Probainognathidae

{{short description|Extinct family of cynodonts}}
{{Automatic taxobox
| fossil_range = {{Fossil range/linked|Ladinian|Carnian}}
| image = Bonacynodon schultzi.jpg
| image_caption = ''[[Bonacynodon]]'' skull
| taxon = Probainognathidae
| authority = [[Alfred Romer|Romer]], 1973
| subdivision_ranks = Genera
| subdivision =
* {{Extinct}}''[[Bonacynodon]]''
* {{Extinct}}''[[Probainognathus]]''
}}

'''Probainognathidae''' is an extinct [[Family (biology)|family]] of [[insectivorous]] [[cynodont]]s which lived in what is now [[South America]] during the [[Middle Triassic|Middle]] to [[Late Triassic]]. The family was established by [[Alfred Romer]] in 1973 and includes two genera, ''[[Probainognathus]]'' from the [[Chañares Formation]] of Argentina and ''[[Bonacynodon]]'' from the [[Dinodontosaurus Assemblage Zone|''Dinodontosaurus'' Assemblage Zone]] of Brazil. Probainognathids were closely related to the clade [[Prozostrodontia]], which includes [[mammal]]s and their close relatives.

== Description ==
[[File:Bonacynodon witout visible ears.png|thumb|left|Restoration of ''Bonacynodon'']]

Members of Probainognathidae were relatively small-bodied animals, with skull lengths of around {{Convert|6|-|7|cm|in}}. The temporal region (area behind the [[eye socket]]s) was rather wide, and longer than the snout. The [[secondary palate]] was well-developed compared to earlier cynodonts, and the portion made up by the [[maxilla]] was larger than the part made from the [[palatine bone]]. The [[Dentary bone|dentary]], the tooth-bearing bone of the lower jaw, was quite tall when seen from the side. The [[mandibular symphysis]] (the joint between the two halves of the dentary) was fused in ''Probainognathus'', but unfused in ''Bonacynodon''. In addition to the ancestral [[Quadrate bone|quadrate]]-[[Articular bone|articular]] jaw joint found in most non-mammalian cynodonts, probainognathids also had an incipient contact between the [[squamosal]] and [[surangular]] bones. The [[canine teeth]] were large and labio-lingually compressed, and in ''Bonacynodon'' they bore a [[serrated]] edge. The [[postcanine]]s had a typical "triconodont" shape, with four main cusps placed in a straight line. Unlike in other basal probainognathians like ''[[Chiniquodon]]'', the cusps were not recurved. The lower postcanines bore a discontinuous [[Cingulum (tooth)|cingulum]] which was restricted to the mesiolingual and distolingual sides of the teeth. The shape of the postcanines indicates that probainognathids most likely were [[insectivorous]].<ref name="Martinelli2016" />

Based on the shape of the [[Infraorbital canal|maxillary canal]], a 2020 paper by Benoit ''et al.'' suggested that ''Probainognathus'' was among the first cynodonts to possess a mobile [[rhinarium]] with [[whiskers]].<ref name="Benoit2020" />

== Classification ==
Probainognathidae was erected in a 1973 paper by the American palaeontologist [[Alfred Romer]] to contain ''[[Probainognathus]]'', a cynodont from the [[Carnian]]-aged [[Chañares Formation]] of Argentina, which Romer had removed from the family [[Chiniquodontidae]]. The family remained [[monotypic]] for a long time, until the genus ''[[Bonacynodon]]'', from the [[Ladinian]]-early Carnian [[Dinodontosaurus Assemblage Zone|''Dinodontosaurus'' Assemblage Zone]] of Brazil, was named in a 2016 paper by Martinelli ''et al.''<ref name="Martinelli2016" /><ref name="Schultz2020" /> This paper also provided a phylogenetic definition of Probainognathidae, as "the clade including the most recent common ancestor of ''Probainognathus jenseni'' and ''Bonacynodon schultzi'', and all its descendants".<ref name="Martinelli2016" />

[[Phylogenetic]] analyses have generally found probainognathids to be relatively early-diverging members of [[Probainognathia]], a clade that includes all cynodonts closer to mammals than to [[Cynognathia]]. The exact placement of probainognathids relative to other basal probainognathians varies between analyses. Some analyses find probainognathids to be very close relatives of [[Prozostrodontia]], a group of advanced probainognathians that includes [[mammal]]s and their close relatives.<ref name="Martinelli2016" /> Some analyses alternatively find [[Ecteniniidae]], a group of large predatory cynodonts, to be closer to prozostrodontians than the probainognathids.<ref name="Stefanello2018" /><ref name="Stefanello2023" />

{{Col-float}}

'''Cladogram from Martinelli ''et al.'' (2016)'''<ref name="Martinelli2016" />
{{Clade|style=font-size:85%; line-height:85%
|label1=[[Probainognathia]]
|1={{Clade
   |1=''[[Ecteninion]]''
   |2={{Clade
      |1=''[[Chiniquodon]]''
      |2={{Clade
         |1={{Clade
            |label1='''Probainognathidae'''
            |1={{Clade
               |1=''[[Bonacynodon]]''
               |2=''[[Probainognathus]]''
            }} }}
         |2={{Clade
            |1=''[[Protheriodon]]''
            |label2=[[Prozostrodontia]]
            |2={{Clade
               |1=''[[Prozostrodon]]''
               |2={{Clade
                  |1=''[[Therioherpeton]]''
                  |2={{Clade
                     |1=[[Tritheledontidae]]
                     |2={{Clade
                        |1=[[Tritylodontidae]]
                        |2={{Clade
                           |1=''[[Botucaraitherium]]''
                           |2={{Clade
                              |1={{Clade
                                 |1=''[[Brasilitherium]]''
                                 |2=''[[Brasilodon]]''
                                 }}
                              |2=[[Mammaliaformes]]
}} }} }} }} }} }} }} }} }} }} }}

{{Col-float-break}}

'''Cladogram from Stefanello ''et al.'' (2023)'''<ref name="Stefanello2023" />
{{Clade|style=font-size:85%; line-height:85%
|label1=[[Probainognathia]]
|1={{Clade
   |1=''[[Lumkuia]]''
   |2={{Clade
      |1=''[[Chiniquodon]]''
      |2={{Clade
         |label1='''Probainognathidae'''
         |1={{Clade
            |1=''[[Bonacynodon]]''
            |2=''[[Probainognathus]]''
         }} }}
      |3={{Clade
         |1=[[Ecteniniidae]]
         |2={{Clade
            |1=''[[Protheriodon]]''
            |label2=[[Prozostrodontia]]
            |2={{Clade
               |1=[[Prozostrodontidae]]
               |2={{Clade
                  |1=''[[Therioherpeton]]''
                  |2={{Clade
                     |1=''[[Irajatherium]]''
                     |2={{Clade
                        |1=''[[Riograndia]]''
                        |2={{Clade
                           |1={{Clade
                              |1=''[[Diarthrognathus]]''
                              |2=''[[Pachygenelus]]''
                              }}
                           |2={{Clade
                              |1=[[Tritylodontidae]]
                              |2={{Clade
                                 |1=''[[Botucaraitherium]]''
                                 |2={{Clade
                                    |1=''[[Brasilodon]]''
                                    |2=[[Mammaliaformes]]
}} }} }} }} }} }} }} }} }} }} }} }} }}

{{Col-float-end}}

==References==
{{Reflist|refs=
<ref name="Benoit2020">{{cite journal |last1=Benoit |first1=J. |last2=Ruf |first2=I. |last3=Miyamae |first3=J. A. |last4=Fernandez |first4=V. |last5=Rodrigues |first5=P. G. |last6=Rubidge |first6=B. S. |title=The Evolution of the Maxillary Canal in Probainognathia (Cynodontia, Synapsida): Reassessment of the Homology of the Infraorbital Foramen in Mammalian Ancestors |journal=Journal of Mammalian Evolution |date=2020 |volume=27 |issue=3 |pages=329–348 |doi=10.1007/s10914-019-09467-8}}</ref>
<ref name="Martinelli2016">{{cite journal |last1=Martinelli |first1=A. G. |last2=Soares |first2=M. B. |last3=Schwanke |first3=C. |title=Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians |journal=PLOS ONE |date=2016 |volume=11 |issue=10 |pages=e0162945 |doi=10.1371/journal.pone.0162945 |pmid=27706191 |pmc=5051967 |bibcode=2016PLoSO..1162945M |language=en |issn=1932-6203|doi-access=free }}</ref>
<ref name="Schultz2020">{{cite journal |last1=Schultz |first1=C. L. |last2=Martinelli |first2=A. G. |last3=Soares |first3=M. B. |last4=Pinheiro |first4=F. L. |last5=Kerber |first5=L. |last6=Horn |first6=B. L. D. |last7=Pretto |first7=F. A. |last8=Müller |first8=R. T. |last9=Melo |first9=T. P. |title=Triassic faunal successions of the Paraná Basin, southern Brazil |journal=Journal of South American Earth Sciences |date=2020 |volume=104 |pages=102846 |doi=10.1016/j.jsames.2020.102846|s2cid=225015757 }}</ref>
<ref name="Stefanello2018">{{cite journal |last1=Stefanello |first1=M. |last2=Müller |first2=R. T. |last3=Kerber |first3=L. |last4=Martínez |first4=R. N. |last5=Dias-Da-Silva |first5=S. |title=Skull anatomy and phylogenetic assessment of a large specimen of Ecteniniidae (Eucynodontia: Probainognathia) from the Upper Triassic of southern Brazil |journal=Zootaxa |date=2018 |volume=4457 |issue=3 |pages=351 |doi=10.11646/zootaxa.4457.3.1}}</ref>
<ref name="Stefanello2023">{{cite journal |last1=Stefanello |first1=M. |last2=Martinelli |first2=A. G. |last3=Müller |first3=R. T. |last4=Dias-da-Silva |first4=S. |last5=Kerber |first5=L. |title=A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts |journal=Journal of Mammalian Evolution |date=2023 |doi=10.1007/s10914-022-09648-y}}</ref>
}}

{{Cynodontia|P.}}
{{Taxonbar|from=Q3068100}}

[[Category:Probainognathia]]
[[Category:Prehistoric therapsid families]]
[[Category:Ladinian first appearances]]
[[Category:Carnian extinctions]]
[[Category:Taxa named by Alfred Romer]]