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Probainognathidae
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<h2 id="description">Description</h2> <p>Members of Probainognathidae were relatively small-bodied animals, with skull lengths of around 6–7 centimetres (2.4–2.8 in). The temporal region (area behind the <a href="/facts/Eye_socket/lJTMFcqy">eye sockets</a>) was rather wide, and longer than the snout. The <a href="/facts/Secondary_palate/Sp8xupIl">secondary palate</a> was well-developed compared to earlier cynodonts, and the portion made up by the <a href="/facts/Maxilla/LbgmySaT">maxilla</a> was larger than the part made from the <a href="/facts/Palatine_bone/H8VBCeA1">palatine bone</a>. The <a href="/facts/Dentary_bone/1ATEfAQa">dentary</a>, the tooth-bearing bone of the lower jaw, was quite tall when seen from the side. The <a href="/facts/Mandibular_symphysis/Ia0g0hwn">mandibular symphysis</a> (the joint between the two halves of the dentary) was fused in <i>Probainognathus</i>, but unfused in <i>Bonacynodon</i>. In addition to the ancestral <a href="/facts/Quadrate_bone/7Jxhkp1B">quadrate</a>-<a href="/facts/Articular_bone/mtMzom1h">articular</a> jaw joint found in most non-mammalian cynodonts, probainognathids also had an incipient contact between the <a href="/facts/Squamosal/y0WLT166">squamosal</a> and <a href="/facts/Surangular/Btcv81Wv">surangular</a> bones. The <a href="/facts/Canine_teeth/p3mRABtg">canine teeth</a> were large and labio-lingually compressed, and in <i>Bonacynodon</i> they bore a <a href="/facts/Serrated/r9adzvtI">serrated</a> edge. The <a href="/facts/Postcanine/q9Cka2Mm">postcanines</a> had a typical "triconodont" shape, with four main cusps placed in a straight line. Unlike in other basal probainognathians like <i><a href="/facts/Chiniquodon/4zwz67DI">Chiniquodon</a></i>, the cusps were not recurved. The lower postcanines bore a discontinuous <a href="/facts/Cingulum_(tooth)/cMqJwxvP">cingulum</a> which was restricted to the mesiolingual and distolingual sides of the teeth. The shape of the postcanines indicates that probainognathids most likely were <a href="/facts/Insectivorous/ukA7UnLr">insectivorous</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p><p>Based on the shape of the <a href="/facts/Infraorbital_canal/FJzm2WA8">maxillary canal</a>, a 2020 paper by Benoit <i>et al.</i> suggested that <i>Probainognathus</i> was among the first cynodonts to possess a mobile <a href="/facts/Rhinarium/XC3UlKDQ">rhinarium</a> with <a href="/facts/Whiskers/cERDJxz8">whiskers</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="classification">Classification</h2> <p>Probainognathidae was erected in a 1973 paper by the American palaeontologist <a href="/facts/Alfred_Romer/MULMjp1P">Alfred Romer</a> to contain <i><a href="/facts/Probainognathus/JgxXatFB">Probainognathus</a></i>, a cynodont from the <a href="/facts/Carnian/DV9VJ0o3">Carnian</a>-aged <a href="/facts/Cha%C3%B1ares_Formation/yWJwWAup">Chañares Formation</a> of Argentina, which Romer had removed from the family <a href="/facts/Chiniquodontidae/8B7Hw0kT">Chiniquodontidae</a>. The family remained <a href="/facts/Monotypic/QvoM9aGP">monotypic</a> for a long time, until the genus <i><a href="/facts/Bonacynodon/bIYL2ndA">Bonacynodon</a></i>, from the <a href="/facts/Ladinian/X9RUy1R2">Ladinian</a>-early Carnian <a href="/facts/Dinodontosaurus_Assemblage_Zone/PfbJXUuv"><i>Dinodontosaurus</i> Assemblage Zone</a> of Brazil, was named in a 2016 paper by Martinelli <i>et al.</i><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> This paper also provided a phylogenetic definition of Probainognathidae, as "the clade including the most recent common ancestor of <i>Probainognathus jenseni</i> and <i>Bonacynodon schultzi</i>, and all its descendants".<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p><p><a href="/facts/Phylogenetic/bw4rsovt">Phylogenetic</a> analyses have generally found probainognathids to be relatively early-diverging members of <a href="/facts/Probainognathia/ST9RQz0x">Probainognathia</a>, a clade that includes all cynodonts closer to mammals than to <a href="/facts/Cynognathia/It6GXN0b">Cynognathia</a>. The exact placement of probainognathids relative to other basal probainognathians varies between analyses. Some analyses find probainognathids to be very close relatives of <a href="/facts/Prozostrodontia/D2eN8cH1">Prozostrodontia</a>, a group of advanced probainognathians that includes <a href="/facts/Mammal/phSwTzBo">mammals</a> and their close relatives.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> Some analyses alternatively find <a href="/facts/Ecteniniidae/xAyxzRkR">Ecteniniidae</a>, a group of large predatory cynodonts, to be closer to prozostrodontians than the probainognathids.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p> <p>Cladogram from Martinelli <i>et al.</i> (2016)<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> <table><tbody><tr><td><a href="/facts/Probainognathia/ST9RQz0x">Probainognathia</a></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Ecteninion/ICNp6CQW">Ecteninion</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Chiniquodon/4zwz67DI">Chiniquodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><table><tbody><tr><td>Probainognathidae</td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Bonacynodon/bIYL2ndA">Bonacynodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><i><a href="/facts/Probainognathus/JgxXatFB">Probainognathus</a></i></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Protheriodon/1Rj0GSbF">Protheriodon</a></i></p></td></tr><tr><td></td></tr><tr><td><a href="/facts/Prozostrodontia/D2eN8cH1">Prozostrodontia</a></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Prozostrodon/CSez9oeM">Prozostrodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Therioherpeton/55gyum2P">Therioherpeton</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><a href="/facts/Tritheledontidae/ebVuU7rS">Tritheledontidae</a></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><a href="/facts/Tritylodontidae/WbAwsPgd">Tritylodontidae</a></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Botucaraitherium/mRElcV3r">Botucaraitherium</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Brasilitherium/9MFRJSS2">Brasilitherium</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><i><a href="/facts/Brasilodon/l2qzzr4q">Brasilodon</a></i></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><a href="/facts/Mammaliaformes/FvX0owYy">Mammaliaformes</a></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table> <p>Cladogram from Stefanello <i>et al.</i> (2023)<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p> <table><tbody><tr><td><a href="/facts/Probainognathia/ST9RQz0x">Probainognathia</a></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Lumkuia/RFJnxGIz">Lumkuia</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Chiniquodon/4zwz67DI">Chiniquodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td>Probainognathidae</td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Bonacynodon/bIYL2ndA">Bonacynodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><i><a href="/facts/Probainognathus/JgxXatFB">Probainognathus</a></i></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><a href="/facts/Ecteniniidae/xAyxzRkR">Ecteniniidae</a></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Protheriodon/1Rj0GSbF">Protheriodon</a></i></p></td></tr><tr><td></td></tr><tr><td><a href="/facts/Prozostrodontia/D2eN8cH1">Prozostrodontia</a></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><a href="/facts/Prozostrodontidae/D2eN8cH1">Prozostrodontidae</a></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Therioherpeton/55gyum2P">Therioherpeton</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Irajatherium/ctj4269X">Irajatherium</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Riograndia/XBacHrBE">Riograndia</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Diarthrognathus/3XczrW7I">Diarthrognathus</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><i><a href="/facts/Pachygenelus/nL9TuvuQ">Pachygenelus</a></i></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><a href="/facts/Tritylodontidae/WbAwsPgd">Tritylodontidae</a></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Botucaraitherium/mRElcV3r">Botucaraitherium</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><table><tbody><tr><td></td><td rowspan="2"><p><i><a href="/facts/Brasilodon/l2qzzr4q">Brasilodon</a></i></p></td></tr><tr><td></td></tr><tr><td></td><td rowspan="2"><p><a href="/facts/Mammaliaformes/FvX0owYy">Mammaliaformes</a></p></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table></td></tr><tr><td></td></tr></tbody></table> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Martinelli, A. G.; Soares, M. B.; Schwanke, C. (2016). "Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians". PLOS ONE. 11 (10): e0162945. Bibcode:2016PLoSO..1162945M. doi:10.1371/journal.pone.0162945. ISSN 1932-6203. PMC 5051967. PMID 27706191. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Benoit, J.; Ruf, I.; Miyamae, J. A.; Fernandez, V.; Rodrigues, P. G.; Rubidge, B. S. (2020). "The Evolution of the Maxillary Canal in Probainognathia (Cynodontia, Synapsida): Reassessment of the Homology of the Infraorbital Foramen in Mammalian Ancestors". Journal of Mammalian Evolution. 27 (3): 329–348. doi:10.1007/s10914-019-09467-8. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Martinelli, A. G.; Soares, M. B.; Schwanke, C. (2016). "Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians". PLOS ONE. 11 (10): e0162945. Bibcode:2016PLoSO..1162945M. doi:10.1371/journal.pone.0162945. ISSN 1932-6203. PMC 5051967. PMID 27706191. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Schultz, C. L.; Martinelli, A. G.; Soares, M. B.; Pinheiro, F. L.; Kerber, L.; Horn, B. L. D.; Pretto, F. A.; Müller, R. T.; Melo, T. P. (2020). "Triassic faunal successions of the Paraná Basin, southern Brazil". Journal of South American Earth Sciences. 104: 102846. doi:10.1016/j.jsames.2020.102846. S2CID 225015757. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Martinelli, A. G.; Soares, M. B.; Schwanke, C. (2016). "Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians". PLOS ONE. 11 (10): e0162945. Bibcode:2016PLoSO..1162945M. doi:10.1371/journal.pone.0162945. ISSN 1932-6203. PMC 5051967. PMID 27706191. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Martinelli, A. G.; Soares, M. B.; Schwanke, C. (2016). "Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians". PLOS ONE. 11 (10): e0162945. Bibcode:2016PLoSO..1162945M. doi:10.1371/journal.pone.0162945. ISSN 1932-6203. PMC 5051967. PMID 27706191. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Stefanello, M.; Müller, R. T.; Kerber, L.; Martínez, R. N.; Dias-Da-Silva, S. (2018). "Skull anatomy and phylogenetic assessment of a large specimen of Ecteniniidae (Eucynodontia: Probainognathia) from the Upper Triassic of southern Brazil". Zootaxa. 4457 (3): 351. doi:10.11646/zootaxa.4457.3.1. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Stefanello, M.; Martinelli, A. G.; Müller, R. T.; Dias-da-Silva, S.; Kerber, L. (2023). "A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts". Journal of Mammalian Evolution. doi:10.1007/s10914-022-09648-y. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Martinelli, A. G.; Soares, M. B.; Schwanke, C. (2016). "Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians". PLOS ONE. 11 (10): e0162945. Bibcode:2016PLoSO..1162945M. doi:10.1371/journal.pone.0162945. ISSN 1932-6203. PMC 5051967. PMID 27706191. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5051967</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Stefanello, M.; Martinelli, A. G.; Müller, R. T.; Dias-da-Silva, S.; Kerber, L. (2023). "A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts". Journal of Mammalian Evolution. doi:10.1007/s10914-022-09648-y. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> </ol>