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{{Short description|Subclass of mammals}} |
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{{automatic taxobox |
{{automatic taxobox |
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| fossil_range = {{fossilrange|Middle Jurassic|Cenomanian|latest=Holocene}}It survives through [[monotremes]], if the group is polyphyletic then it also survives through [[Boreosphenida]] |
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| fossil_range = [[Late Triassic]] - [[Holocene]], {{fossilrange|210|0}} |
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| image = |
| image = |
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| image_caption = |
| image_caption = |
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| image2 = Ambondro lingual.jpg |
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| image2_caption = Jaw fragment of ''[[Ambondro mahabo]]'' |
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| taxon = Australosphenida |
| taxon = Australosphenida |
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| authority = Luo, Cifelli, & Kielan-Jaworowska, 2001 |
| authority = Luo, Cifelli, & Kielan-Jaworowska, 2001 |
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| subdivision_ranks = Taxa |
| subdivision_ranks = Taxa |
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| subdivision = |
| subdivision = * †[[Ausktribosphenidae]] |
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* †[[ |
* †[[Bishopidae]] |
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* †[[Henosferidae]] |
* †[[Henosferidae]] |
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* |
* [[Monotremaformes]]? |
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* [[ |
** †[[Steropodontidae]] |
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** [[Monotremata]]? |
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*†''[[Tendagurutherium]]'' (?) |
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And see text |
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*†''[[Vincelestes]]'' (?) |
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}} |
}} |
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The '''Australosphenida''' are a |
The '''Australosphenida''' are a [[clade]] of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of [[Gondwana]]. Although they have often been suggested to have acquired tribosphenic molars independently from those of [[Tribosphenida]], this has been disputed. Fossils of australosphenidans have been found from the [[Jurassic]] of [[Madagascar]] and [[Argentina]], and [[Cretaceous]] of Australia and Argentina. [[Monotremes]] have also been considered a partofthis group in many studies, but this is also disputed. |
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== Taxonomy == |
== Taxonomy == |
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This grouping includes the following taxa: |
This grouping includes the following taxa: |
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*[[Monotremata]], divided into the families [[Ornithorhynchidae]] (platypus), [[Steropodontidae]] and [[Tachyglossidae]] (echidnas) and the genus ''[[Kryoryctes]]'' |
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*†[[Henosferidae]], including the [[genus|genera]] ''[[Ambondro (genus)|Ambondro]]'', ''[[Asfaltomylos]]'', and ''[[Henosferus]]'' from the [[Jurassic]] of Argentina and Madagascar. |
*†[[Henosferidae]], including the [[genus|genera]] ''[[Ambondro (genus)|Ambondro]]'', ''[[Asfaltomylos]]'', and ''[[Henosferus]]'' from the [[Jurassic]] of Argentina and Madagascar. |
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*†[[Ausktribosphenidae]], including the |
*†[[Ausktribosphenidae]], including the genus ''[[Ausktribosphenos]]'' from the Lower [[Cretaceous]] of Australia |
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*†[[Bishopidae]] including ''[[Bishops (mammal)|Bishops]]'' from the Lower [[Cretaceous]] of Australia and an unnamed genus from the Mid-Cretaceous of Argentina (the latter of which was originally attributed to Ausktribosphenidae).<ref>{{Cite journal |last=Martin |first=Thomas |last2=Goin |first2=Francisco J. |last3=Schultz |first3=Julia A. |last4=Gelfo |first4=Javier N. |date=May 2022 |title=Early Late Cretaceous mammals from southern Patagonia (Santa Cruz province, Argentina) |url=https://linkinghub.elsevier.com/retrieve/pii/S019566712100375X |journal=Cretaceous Research |language=en |volume=133 |pages=105127 |doi=10.1016/j.cretres.2021.105127}}</ref><ref name=":0" /> |
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*†[[Kollikodontidae]], formerly included in true monotremes but now thought to form an outgroup.<ref>Rebecca Pian; Michael Archer; Suzanne J. Hand; Robin M.D. Beck; Andrew Cody (2016). "The upper dentition and relationships of the enigmatic Australian Cretaceous mammal Kollikodon ritchiei". Memoirs of Museum Victoria. 74: 97–105.</ref> |
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*†''[[Vincelestes]]'', sometimes recovered as an australosphenidan (when not inversely considered a [[cladotheria]]n).<ref>Nicholas Chimento, Frederico Agnolin, Agustin Martinelli, Mesozoic Mammals from South America: Implications for understanding early mammalian faunas from Gondwana, May 2016</ref><ref>José Bonaparte, On the phylogenetic relationships of Vincelestes neuquenianus, Published online: 17 Sep 2008</ref> |
*†?''[[Vincelestes]]'', sometimes recovered as an australosphenidan (when not inversely considered a [[cladotheria]]n).<ref name="Chimento, Agnolin and Martinelli 2016">Nicholas Chimento, Frederico Agnolin, Agustin Martinelli, Mesozoic Mammals from South America: Implications for understanding early mammalian faunas from Gondwana, May 2016</ref><ref>José Bonaparte, On the phylogenetic relationships of Vincelestes neuquenianus, Published online: 17 Sep 2008</ref> |
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*†''[[Tendagurutherium]]'', |
*†?''[[Tendagurutherium]]'', recovered as an australosphenidan in one study.<ref name="Chimento, Agnolin and Martinelli 2016" /> |
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The clade Australosphenida was proposed by Luo ''et al.'' (2001, 2002) and was initially left unranked, as the authors do not apply the [[Linnaean taxonomy|Linnaean hierarchy]]. In Benton (2005), it is ranked as a '[[Linnaean taxonomy#Taxonomic ranks|superdivision]]', i.e. one or two levels below the [[infraclass]]. |
The clade Australosphenida was proposed by Luo ''et al.'' (2001, 2002) and was initially left unranked, as the authors do not apply the [[Linnaean taxonomy|Linnaean hierarchy]]. In Benton (2005), it is ranked as a '[[Linnaean taxonomy#Taxonomic ranks|superdivision]]', i.e. one or two levels below the [[infraclass]]. |
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== |
== Evolution == |
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The grouping embodies a hypothesis about the evolution of [[molar (tooth)|molar]] teeth in mammals. Living monotremes are toothless as adults, but the juvenile platypus, fossil monotremes and Ausktribosphenida all share a pattern of three molar [[cusp (dentistry)|cusps]] arranged in a triangle or V shape, which is known as the [[Tribosphenic molar|tribosphenic]] type of molar. Tribosphenic molars have long been held to characterize the subclass [[Theria]] ([[marsupial]]s, [[placental]]s and their extinct relatives), while monotremes were thought to be related to fossil groups with a linear alignment of cusps: [[morganucodon]]tids, [[docodont]]s, [[triconodont]]s and [[multituberculate]]s, all of which were united with the monotremes into the 'subclass [[Prototheria]]'. Defined in this way, the 'Prototheria' is no longer recognised as a valid clade, since the linear cusp pattern is a primitive condition within Mammalia and cannot supply the shared derived character, which is required to establish a subgroup. Instead, the available evidence suggests that the monotremes descend from a [[Mesozoic]] radiation of tribosphenic mammals in the southern continents (hence the name Australosphenida, meaning 'southern wedges'), but this interpretation is highly controversial. |
The grouping embodies a hypothesis about the evolution of [[molar (tooth)|molar]] teeth in mammals. Living monotremes are toothless as adults, but the juvenile platypus, fossil monotremes and Ausktribosphenida all share a pattern of three molar [[cusp (dentistry)|cusps]] arranged in a triangle or V shape, which is known as the [[Tribosphenic molar|tribosphenic]] type of molar. Tribosphenic molars have long been held to characterize the subclass [[Theria]] ([[marsupial]]s, [[placental]]s and their extinct relatives), while monotremes were thought to be related to fossil groups with a linear alignment of cusps: [[morganucodon]]tids, [[docodont]]s, [[triconodont]]s and [[multituberculate]]s, all of which were united with the monotremes into the 'subclass [[Prototheria]]'. Defined in this way, the 'Prototheria' is no longer recognised as a valid clade, since the linear cusp pattern is a primitive condition within Mammalia and cannot supply the shared derived character, which is required to establish a subgroup. Instead, the available evidence suggests that the monotremes descend from a [[Mesozoic]] radiation of tribosphenic mammals in the southern continents (hence the name Australosphenida, meaning 'southern wedges'), but this interpretation is highly controversial. |
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According to Luo ''et al.'', tribosphenic molars were evolved by the Australosphenida independently of the true [[Tribosphenida]], or [[Boreosphenida]] (that is, the therians and their relatives) in the northern continents. Others contend that the |
According to Luo ''et al.'', tribosphenic molars were evolved by the Australosphenida independently of the true [[Tribosphenida]], or [[Boreosphenida]] (that is, the therians and their relatives) in the northern continents. Others contend that the ausktribosphenids (two families of the Australian Cretaceous tribosphenids) in fact belong to the placentals and were therefore true tribosphenids, but unrelated to the ancestry of the monotremes.<ref>Benton 2005: 300, 306-308.</ref> |
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Most recent [[phylogenetics|phylogenetic]] studies |
Most recent [[phylogenetics|phylogenetic]] studies lump henosferids and aukstribosphenids alongside monotremes.<ref>Richard Stephen Thompson, Rachel O'Meara, Were There Miocene Meridiolestidans? Assessing the Phylogenetic Placement of Necrolestes patagonensis and the Presence of a 40 Million Year Meridiolestidan Ghost Lineage, Article in Journal of Mammalian Evolution · September 2014 DOI: 10.1007/s10914-013-9252-3</ref><ref name="Kollikodon ritchiei 2016">Rebecca Pian; Michael Archer; Suzanne J. Hand; Robin M.D. Beck; Andrew Cody (2016). "The upper dentition and relationships of the enigmatic Australian Cretaceous mammal Kollikodon ritchiei". Memoirs of Museum Victoria. 74: 97–105.</ref> However, in a 2022 review of montreme evolution noted that most primitive monotreme ''[[Teinolophos]]'' differed substantially from other non-monotreme Australosphenidans'','' having five molars as opposed to three in all other non-monotreme australosphenidans, and having non-tribosphenic molars, meaning that monotremes and non-monotreme australosphenidans were likely unrelated.<ref>{{Cite journal |last1=Flannery |first1=Timothy F. |last2=Rich |first2=Thomas H. |last3=Vickers-Rich |first3=Patricia |last4=Ziegler |first4=Tim |last5=Veatch |first5=E. Grace |last6=Helgen |first6=Kristofer M. |date=2022-01-02 |title=A review of monotreme (Monotremata) evolution |journal=Alcheringa: An Australasian Journal of Palaeontology |language=en |volume=46 |issue=1 |pages=3–20 |doi=10.1080/03115518.2022.2025900 |issn=0311-5518|doi-access=free }}</ref> Later, Flannery and coauthors suggested that the core grouping of australosphenidans (excluding monotremes and others australosphenidans with ''[[Steropodon]]'') were actually stem-[[theria]]ns as members of [[Tribosphenida]], with the group representing a paraphyletic grade, with Bishopidae more closely related to Theria than to other australosphenidans.<ref name=":0">{{Cite journal |last1=Flannery |first1=Timothy F. |last2=Rich |first2=Thomas H. |last3=Vickers-Rich |first3=Patricia |last4=Veatch |first4=E. Grace |last5=Helgen |first5=Kristofer M. |date=2022-11-01 |title=The Gondwanan Origin of Tribosphenida (Mammalia) |url=https://www.tandfonline.com/doi/full/10.1080/03115518.2022.2132288 |journal=Alcheringa: An Australasian Journal of Palaeontology |volume=46 |issue=3–4 |language=en |pages=277–290 |doi=10.1080/03115518.2022.2132288 |s2cid=253323862 |issn=0311-5518|doi-access=free }}</ref> |
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==Notes== |
==Notes== |
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| Line 41: | Line 43: | ||
==References== |
==References== |
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* {{Cite book |
* {{Cite book |
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| last = Benton | first = Michael J. | |
| last = Benton | first = Michael J. | author-link = Michael J. Benton |
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| title = Vertebrate Palaeontology | edition = 3rd |
| title = Vertebrate Palaeontology | edition = 3rd |
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| publisher = Blackwell Publishing | location = Oxford | year = 2005 |
| publisher = Blackwell Publishing | location = Oxford | year = 2005 |
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| Line 51: | Line 53: | ||
| last3 = Kielan-Jaworowska | first3 = Zofia |
| last3 = Kielan-Jaworowska | first3 = Zofia |
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| title = Dual origin of tribosphenic mammals |
| title = Dual origin of tribosphenic mammals |
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| journal = Nature | year = 2001 | volume = 409 | |
| journal = Nature | year = 2001 | volume = 409 | issue = 6816 |
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| pages = 53–57 |
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| doi = 10.1038/35051023 | pmid=11343108 |
| doi = 10.1038/35051023 | pmid=11343108 |
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| s2cid = 4342585 |
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}} |
}} |
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* {{Cite journal |
* {{Cite journal |
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| last1 = Luo | first1 = Zhe-Xi |
| last1 = Luo | first1 = Zhe-Xi |
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| Australosphenida
It survives through monotremes, if the group is polyphyletic then it also survives through Boreosphenida | |
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| Jaw fragment of Ambondro mahabo | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Clade: | Australosphenida Luo, Cifelli, & Kielan-Jaworowska, 2001 |
| Taxa | |
|
And see text | |
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. Although they have often been suggested to have acquired tribosphenic molars independently from those of Tribosphenida, this has been disputed. Fossils of australosphenidans have been found from the JurassicofMadagascar and Argentina, and Cretaceous of Australia and Argentina. Monotremes have also been considered a part of this group in many studies, but this is also disputed.
This grouping includes the following taxa:
The clade Australosphenida was proposed by Luo et al. (2001, 2002) and was initially left unranked, as the authors do not apply the Linnaean hierarchy. In Benton (2005), it is ranked as a 'superdivision', i.e. one or two levels below the infraclass.
The grouping embodies a hypothesis about the evolution of molar teeth in mammals. Living monotremes are toothless as adults, but the juvenile platypus, fossil monotremes and Ausktribosphenida all share a pattern of three molar cusps arranged in a triangle or V shape, which is known as the tribosphenic type of molar. Tribosphenic molars have long been held to characterize the subclass Theria (marsupials, placentals and their extinct relatives), while monotremes were thought to be related to fossil groups with a linear alignment of cusps: morganucodontids, docodonts, triconodonts and multituberculates, all of which were united with the monotremes into the 'subclass Prototheria'. Defined in this way, the 'Prototheria' is no longer recognised as a valid clade, since the linear cusp pattern is a primitive condition within Mammalia and cannot supply the shared derived character, which is required to establish a subgroup. Instead, the available evidence suggests that the monotremes descend from a Mesozoic radiation of tribosphenic mammals in the southern continents (hence the name Australosphenida, meaning 'southern wedges'), but this interpretation is highly controversial.
According to Luo et al., tribosphenic molars were evolved by the Australosphenida independently of the true Tribosphenida, or Boreosphenida (that is, the therians and their relatives) in the northern continents. Others contend that the ausktribosphenids (two families of the Australian Cretaceous tribosphenids) in fact belong to the placentals and were therefore true tribosphenids, but unrelated to the ancestry of the monotremes.[5]
Most recent phylogenetic studies lump henosferids and aukstribosphenids alongside monotremes.[6][7] However, in a 2022 review of montreme evolution noted that most primitive monotreme Teinolophos differed substantially from other non-monotreme Australosphenidans, having five molars as opposed to three in all other non-monotreme australosphenidans, and having non-tribosphenic molars, meaning that monotremes and non-monotreme australosphenidans were likely unrelated.[8] Later, Flannery and coauthors suggested that the core grouping of australosphenidans (excluding monotremes and others australosphenidans with Steropodon) were actually stem-therians as members of Tribosphenida, with the group representing a paraphyletic grade, with Bishopidae more closely related to Theria than to other australosphenidans.[2]
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Extant mammal orders
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| Yinotheria |
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| Theria |
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| Australosphenida |
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