| 词条 | Biseridens |
| 释义 |
| image = Biseridens qilianicus.jpg | image_caption = Life illustration of Biseridens qilianicus | fossil_range = Middle Permian, {{fossilrange|270}} | display_parents = 2 | genus = Biseridens | parent_authority = Li and Cheng, 1997 | species = qilianicus | authority = Li and Cheng, 1997 }}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] DescriptionBiseridens 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 {{convert|17|cm|in}} long, relatively small compared to other basal anomodonts. ClassificationThe 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] {{clade| style=font-size:85%;line-height:80%|label1=Therapsida |1={{clade |label1=unnamed |1={{clade |1=Biarmosuchia |2=Gorgonopsia }} |label2=unnamed |2={{clade |1=Dinocephalia |label2= Anomodontia |2={{clade |1=Biseridens |label2=unnamed |2={{clade |1=Anomocephalus |label2=unnamed |2={{clade |label1= Venyukovioidea |1={{clade |1=Otsheria |label2=unnamed |2={{clade |1=Ulemica |2=Suminia}} }} |label2= Chainosauria |2={{clade |1=Patranomodon |label2=unnamed |2={{clade |1=Galeops |2=Eodicynodon }} }} }} }} }} }} }} }} See also{{Portal|Paleontology}}
References1. ^1 {{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}} {{Anomodontia|A.}}{{Taxonbar|from=Q2154061}}{{anomodont-stub}}2. ^{{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}} 3. ^{{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}} 4. ^{{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}} 6 : Anomodont genera|Guadalupian synapsids|Permian synapsids of Asia|Fossil taxa described in 1997|Guadalupian genus first appearances|Guadalupian genus extinctions |
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