New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution
A new specimen of Lactodens sheni, the only known spalacolestine from the Early Cretaceous Jehol Biota, is reported from the Jiufotang Formation, Liaoning, China. The description focuses on the dental and mandibular morphologies from both the new specimen and the holotype, particularly those tha...
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Institute of Paleobiology PAS
2022-03-01
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| Series: | Acta Palaeontologica Polonica |
| Subjects: | |
| Online Access: | https://www.app.pan.pl/archive/published/app67/app009182021.pdf |
| _version_ | 1818018946534604800 |
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| author | FANGYUAN MAO CUNYU LIU JIN MENG |
| author_facet | FANGYUAN MAO CUNYU LIU JIN MENG |
| author_sort | FANGYUAN MAO |
| collection | DOAJ |
| description | A new specimen of Lactodens sheni, the only known spalacolestine from the Early Cretaceous Jehol Biota, is reported
from the Jiufotang Formation, Liaoning, China. The description focuses on the dental and mandibular morphologies
from both the new specimen and the holotype, particularly those that were unknown or poorly known from the holotype
when the taxon was established. As revealed primarily by high-resolution computed tomography, morphologies and size
gradient of the lower molars and detailed features of the mandibles, such as the masseteric foramen, can be unequivocally described. The dental and mandibular morphologies of Lactodens are compared with those of Origolestes lii, also
from the Jehol Biota; these two taxa represent by far the best specimens in Spalacotheriidae and Zhangheotheriidae,
respectively, and could be used as the representatives of their own groups in future higher-level phylogenetic analysis of
mammals. The two taxa display considerable differences in dental and mandibular features, probably indicating a deeper
split of spalacotheriids and zhangheotheriids than previously thought. Absence of the Meckelian groove in Lactodens,
contrasting to the distinct one that holds a sizable Meckel’s cartilage in adult Origolestes, suggests an independent evolution of the definitive mammalian middle ear within “symmetrodontans”. The morphological gradient in the tooth row
and association of the upper and lower dentitions from the same individual animal are also instructive for interpreting
molar variations and evolution in “symmetrodontans” and mammals. |
| first_indexed | 2024-04-14T07:46:23Z |
| format | Article |
| id | doaj.art-b3ab2eea1b34414fa39076285da85671 |
| institution | Directory Open Access Journal |
| issn | 0567-7920 1732-2421 |
| language | English |
| last_indexed | 2024-04-14T07:46:23Z |
| publishDate | 2022-03-01 |
| publisher | Institute of Paleobiology PAS |
| record_format | Article |
| series | Acta Palaeontologica Polonica |
| spelling | doaj.art-b3ab2eea1b34414fa39076285da856712022-12-22T02:05:20ZengInstitute of Paleobiology PASActa Palaeontologica Polonica0567-79201732-24212022-03-0167113515310.4202/app.00918.2021New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolutionFANGYUAN MAO0CUNYU LIU1JIN MENG2Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Division of Paleontology, American Museum of Natural History, New York, New York 10024, USABeipiao Pterosaur Museum of China, Beipiao County, Liaoning Province, 122100, China.Division of Paleontology, American Museum of Natural History, New York, New York 10024, USA; Earth and Environmental Sciences, Graduate Center, City University of New York, New York, 10016, USAA new specimen of Lactodens sheni, the only known spalacolestine from the Early Cretaceous Jehol Biota, is reported from the Jiufotang Formation, Liaoning, China. The description focuses on the dental and mandibular morphologies from both the new specimen and the holotype, particularly those that were unknown or poorly known from the holotype when the taxon was established. As revealed primarily by high-resolution computed tomography, morphologies and size gradient of the lower molars and detailed features of the mandibles, such as the masseteric foramen, can be unequivocally described. The dental and mandibular morphologies of Lactodens are compared with those of Origolestes lii, also from the Jehol Biota; these two taxa represent by far the best specimens in Spalacotheriidae and Zhangheotheriidae, respectively, and could be used as the representatives of their own groups in future higher-level phylogenetic analysis of mammals. The two taxa display considerable differences in dental and mandibular features, probably indicating a deeper split of spalacotheriids and zhangheotheriids than previously thought. Absence of the Meckelian groove in Lactodens, contrasting to the distinct one that holds a sizable Meckel’s cartilage in adult Origolestes, suggests an independent evolution of the definitive mammalian middle ear within “symmetrodontans”. The morphological gradient in the tooth row and association of the upper and lower dentitions from the same individual animal are also instructive for interpreting molar variations and evolution in “symmetrodontans” and mammals. https://www.app.pan.pl/archive/published/app67/app009182021.pdfmammaliasymmetrodontaspalacotheriidaezhangheotheriidaedental morphologymandiblemiddle earcretaceousyixian formationchina |
| spellingShingle | FANGYUAN MAO CUNYU LIU JIN MENG New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution Acta Palaeontologica Polonica mammalia symmetrodonta spalacotheriidae zhangheotheriidae dental morphology mandible middle ear cretaceous yixian formation china |
| title | New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution |
| title_full | New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution |
| title_fullStr | New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution |
| title_full_unstemmed | New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution |
| title_short | New material of the trechnotherian mammal Lactodens from the Early Cretaceous Jehol Biota: Comparison with Origolestes and implications for mammal evolution |
| title_sort | new material of the trechnotherian mammal lactodens from the early cretaceous jehol biota comparison with origolestes and implications for mammal evolution |
| topic | mammalia symmetrodonta spalacotheriidae zhangheotheriidae dental morphology mandible middle ear cretaceous yixian formation china |
| url | https://www.app.pan.pl/archive/published/app67/app009182021.pdf |
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