Biseridens: Difference between revisions
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| image = Biseridens qilianicus.jpg |
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| image_caption = Life illustration of ''Biseridens qilianicus'' |
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| fossil_range = [[Middle Permian]], {{fossilrange|270}} |
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'''''Biseridens''''' is an extinct genus of [[therapsid]] |
'''''Biseridens''''' ("two rows of teeth") is an [[extinct]] [[genus]] of [[anomodont]] [[therapsid]], and one of the most [[basal (phylogenetics)|basal]] anomodont genera known. Originally known from a partial skull misidentified as an '[[Eotitanosuchidae|eotitanosuchian]]' in 1997, another well-preserved skull was found in the [[Xidagou Formation]], an outcropping in the [[Qilian Mountains]] of [[Gansu]], [[China]], in 2009 that clarified it's relationships to anomodonts, such as the [[dicynodonts]].<ref name=LRL09>{{cite journal |last=Liu |first=J. |author2=Rubidge, B. |author3= Li, J. |year=2009 |title=A new specimen of ''Biseridens qilianicus'' indicates its phylogenetic position as the most basal anomodont |journal=Proceedings of the Royal Society B |pmid=19640887 |volume=277 |issue=1679 |pmc=2842672 |pages=285–292 |doi=10.1098/rspb.2009.0883}}</ref> |
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A well-preserved skull found from the [[Xidagou Formation]], outcropping in the Qilian Mountains of Gansu, China |
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==Description== |
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''Biseridens'' is known mostly from [[skull]] and [[mandible|jaw material]], as well as a series of 14 [[vertebrae]] associated with one skull. Like other anomodonts, the region of the skull in front of the eyes is relatively short compared to other therapsids. The [[orbits]] are large and rounded, and the [[temporal fenestra]] are large and wide and broad [[zygomatic arches]], similar to but not as developed as those of later dicynodonts. The skull is estimated to be at least {{convert|17|cm|in}} long, relatively small compared to other basal anomodonts. |
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==Classification== |
==Classification== |
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The holotype and paratype of ''Biseridens'' were initially referred to Eotitanosuchia, a former [[suborder]] of therapsids that included various groups of early therapsids (although the range inclusion varied between authors). The genus was named from the [[Latin]] ''biseri''- for "double rows" and -''dens'' ("teeth") to refer to the paired double rows of cheek teeth in each jaw, while the species was named after the Qilian mountains where the fossils were discovered. They also assigned ''Biseridens'' to a distinct new family of eotitanosuchians, the '''Biseridensidae''', although they did not provide a diagnosis for this family outside of the genus itself.<ref name=LiCheng>{{Cite journal |last=Li |first=Jinling |last2=Cheng |first2=Zhengwu |date=1997 |title=First discovery of eotitanosuchian (Therapsida, Synapsida) of China |url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200812/W020090813369738831280.pdf |journal=Vertebrata Palasiatica|volume=35|issue=4|pages=268–282}}</ref> |
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Synapomorphies distinguish ''Biseridens'' as an anomodont and not an eotitanosuchian as previously described: short snout; dorsally elevated zygomatic arch and septomaxilla lacking elongated posterodorsal process between nasal and maxilla. The presence of a differentiated tooth row; denticles on vomer, palatine and pterygoid; contact between tabular and opisthotic; lateral process of transverse flange of pterygoid free of posterior ramus and absence of mandibular foramen exclude it from other anomodonts. Cladistic analysis indicates ''Biseridens'' to be the most basal anomodont, highlights separate Laurasian and Gondwanan basal anomodont clades and suggests that dicynodonts had their origins in the Gondwanan clade.<ref name=LRL09/> |
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Although relatively primitive, a number of shared traits ([[synapomorphies]]) ally ''Biseridens'' with anomodonts including the shortened snout, raised zygomatic arch and exclusion of the septomaxilla between the maxilla and nasals. However, it retains a number of primitive traits that exclude it from the more derived anomodonts, including the differentiated tooth row, palatal teeth, contact between tabular and opisthotic; lateral process of transverse flange of pterygoid free of posterior ramus and absence of mandibular foramen. Several cladistic analyses indicate that ''Biseridens'' is the most [[Basal_(phylogenetics)|basal]] anomodont known, including that of Liu and colleagues (2009) shown below,<ref name=LRL09/> as well as those of Cisneros and colleagues (2011)<ref name="Cisneros2011">{{Cite journal|author1=Cisneros, J.C. |author2=Abdala, F. |author3=Rubidge, B.S. |author4=Dentzien-Dias, D. |author5=Bueno, A.O. |year=2011|title=Dental Occlusion in a 260-Million-Year-Old Therapsid with Saber Canines from the Permian of Brazil|journal=Science|volume=331|pages=1603–1605|doi=10.1126/science.1200305|pmid=21436452}}</ref> and Kammerer and colleagues (2013):<ref name=EubrachiosaurusRev>{{Cite journal | last1 = Kammerer | first1 = C. F. | last2 = Fröbisch | first2 = J. R. | last3 = Angielczyk | first3 = K. D. | editor1-last = Farke | editor1-first = Andrew A | title = On the Validity and Phylogenetic Position of Eubrachiosaurus browni, a Kannemeyeriiform Dicynodont (Anomodontia) from Triassic North America | doi = 10.1371/journal.pone.0064203 | journal = PLoS ONE | volume = 8 | issue = 5 | pages = e64203 | year = 2013 | pmid = 23741307| pmc = 3669350}}</ref> |
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{{clade| style=font-size:85%;line-height:80% |
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|label1=[[Therapsida]] |
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|1={{clade |
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|label1=<span style="color:white;">unnamed</span> |
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|1={{clade |
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|1=[[Biarmosuchia]] [[File:Biarmosuchus.jpg|50px]] |
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|2=[[Gorgonopsia]] [[File:Gorgonops_whaitsii1.jpg|50px]]}} |
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|label2=<span style="color:white;">unnamed</span> |
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|2={{clade |
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|1=[[Dinocephalia]] [[File:Moschops_BW.jpg|50px]] |
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|label2= [[Anomodontia]] |
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|2={{clade |
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|1='''''Biseridens''''' |
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|label2=<span style="color:white;">unnamed</span> |
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|2={{clade |
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|1=''[[Anomocephalus]]'' |
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|label2=<span style="color:white;">unnamed</span> |
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|2={{clade |
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|label1= [[Venyukovioidea]] |
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|1={{clade |
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|1=''[[Otsheria]]'' |
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|label2=<span style="color:white;">unnamed</span> |
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|2={{clade |
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|1=''[[Ulemica]]'' |
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|2=''[[Suminia]]''}} }} |
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|label2= [[Chainosauria]] |
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|2={{clade |
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|1=''[[Patranomodon]]'' |
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|label2=<span style="color:white;">unnamed</span> |
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|2={{clade |
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|1=''[[Galeops]]'' |
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|2=''[[Eodicynodon]]'' [[File:Eodicynodon_BW.jpg|50px]]}} }} }} }} }} |
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}} }} }} |
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==See also== |
==See also== |
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Revision as of 01:39, 3 December 2018
| Biseridens Temporal range: Middle Permian,
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|---|---|
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| Life illustration of Biseridens qilianicus | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Suborder: | †Anomodontia |
| Genus: | †Biseridens Li and Cheng, 1997 |
| Species: | †B. qilianicus
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| Binomial name | |
| †Biseridens qilianicus Li and Cheng, 1997
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Biseridens ("two rows of teeth") is an extinct genus of anomodont therapsid, and one of the most basal anomodont genera known. Originally known from a partial skull misidentified as an 'eotitanosuchian' in 1997, another well-preserved skull was found in the Xidagou Formation, an outcropping in the Qilian Mountains of Gansu, China, in 2009 that clarified it's relationships to anomodonts, such as the dicynodonts.[1]
Description
Biseridens is known mostly from skull and jaw material, as well as a series of 14 vertebrae associated with one skull. Like other anomodonts, the region of the skull in front of the eyes is relatively short compared to other therapsids. The orbits are large and rounded, and the temporal fenestra are large and wide and broad zygomatic arches, similar to but not as developed as those of later dicynodonts. The skull is estimated to be at least 17 centimetres (6.7 in) long, relatively small compared to other basal anomodonts.
Classification
The holotype and paratype of Biseridens were initially referred to Eotitanosuchia, a former suborder of therapsids that included various groups of early therapsids (although the range inclusion varied between authors). The genus was named from the Latin biseri- for "double rows" and -dens ("teeth") to refer to the paired double rows of cheek teeth in each jaw, while the species was named after the Qilian mountains where the fossils were discovered. They also assigned Biseridens to a distinct new family of eotitanosuchians, the Biseridensidae, although they did not provide a diagnosis for this family outside of the genus itself.[2]
Although relatively primitive, a number of shared traits (synapomorphies) ally Biseridens with anomodonts including the shortened snout, raised zygomatic arch and exclusion of the septomaxilla between the maxilla and nasals. However, it retains a number of primitive traits that exclude it from the more derived anomodonts, including the differentiated tooth row, palatal teeth, contact between tabular and opisthotic; lateral process of transverse flange of pterygoid free of posterior ramus and absence of mandibular foramen. Several cladistic analyses indicate that Biseridens is the most basal anomodont known, including that of Liu and colleagues (2009) shown below,[1] as well as those of Cisneros and colleagues (2011)[3] and Kammerer and colleagues (2013):[4]
| Therapsida |
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See also
References
- ^ a b Liu, J.; Rubidge, B.; Li, J. (2009). "A new specimen of Biseridens qilianicus indicates its phylogenetic position as the most basal anomodont". Proceedings of the Royal Society B. 277 (1679): 285–292. doi:10.1098/rspb.2009.0883. PMC 2842672. PMID 19640887.
- ^ Li, Jinling; Cheng, Zhengwu (1997). "First discovery of eotitanosuchian (Therapsida, Synapsida) of China" (PDF). Vertebrata Palasiatica. 35 (4): 268–282.
- ^ Cisneros, J.C.; Abdala, F.; Rubidge, B.S.; Dentzien-Dias, D.; Bueno, A.O. (2011). "Dental Occlusion in a 260-Million-Year-Old Therapsid with Saber Canines from the Permian of Brazil". Science. 331: 1603–1605. doi:10.1126/science.1200305. PMID 21436452.
- ^ Kammerer, C. F.; Fröbisch, J. R.; Angielczyk, K. D. (2013). Farke, Andrew A (ed.). "On the Validity and Phylogenetic Position of Eubrachiosaurus browni, a Kannemeyeriiform Dicynodont (Anomodontia) from Triassic North America". PLoS ONE. 8 (5): e64203. doi:10.1371/journal.pone.0064203. PMC 3669350. PMID 23741307.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
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