科研之友
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摘要
A new arctocyonid 'condylarth', Sigynorum magnadivisus gen. et sp. nov., is described from a recently discovered earliest Paleocene (early Puercan) fauna from the China Butte Member of the Fort Union Formation in the Great Divide Basin, southern Wyoming. Based on a sample of 18 specimens (including 14 partial dentaries) whose combined dentitions represent the p2, p4 and m1-3, the new taxon appears most similar in size and molar morphology to the early Puercan arctocyonid Oxyprimus erikseni, but differs in its p4 morphology. To examine the relationship between S. magnadivisus and other Puercan 'condylarths' from the Western Interior of North America, a phylogenetic analysis was performed, utilizing 23 taxa (including 21 'condylarth' species and the outgroup taxa Cimolestes and Gypsonictops) and 73 dental characters. The resulting strict consensus tree of 248 steps confirms the close relationship between S. magnadivisus and O. erikseni. Interestingly, our phylogenetic analysis also suggests that Puercan Periptychidae is paraphyletic; the early Puercan periptychids Mimatuta morgoth, Mimatuta minuial, Maiorana noctiluca and Auraria urbana appear more closely allied with arctocyonid and hyopsodontid taxa, while other Puercan periptychids Conacodon spp., Ampliconus browni, Alticonus gazini, Oxyacodon spp. and Mithrandir gillianus fall into a separate monophyletic clade. This analysis is among the first to focus on a large set of Puercan 'condylarth' taxa across geographically widespread localities, and, with the addition of the new species from the Great Divide Basin, suggests that diversity among early Puercan 'condylarths' is higher than previously recognized.
- 出版日期2016
