The Earliest Fossil of the African Clawed Frog (Genus Xenopus) from Sub-Saharan Africa
The Earliest Fossil of the African Clawed Frog (Genus Xenopus) from Sub-Saharan Africa
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DOI：
10.1670/18-139
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发表时间：
2019-05-01
影响因子：
0.8
通讯作者：
Stevens, Nancy J.
中科院分区：
文献类型：
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作者：
Blackburn, David C.;Paluh, Daniel J.;Stevens, Nancy J.
尽管类蛙的化石记录比其他无尾类分支更广泛，但在整个新生代，冠群属的记录却很少。我们报告了坦桑尼亚西南部 Nsungwe 地层（距今约 2500 万年前；渐新世）中分离出的神经颅骨，为撒哈拉以南非洲存在爪蟾属提供了最早的证据。该标本保存完好，使我们能够使用三维几何形态测量学，根据微计算机断层扫描，将这种神经颅骨的形状与所有现存非洲爪蟾物种的形状进行比较。分析显示，这块小化石类似于现存的小型爪蟾物种，例如长足爪蟾。神经颅骨化石保留了骨化良好的鼻顶盖和鼻中隔，后者分隔了大的卵圆形嗅孔，导致原始孔周围的区域比在现有类似大小的物种中观察到的更加骨化。 Nsungwe 地层的 pipoid 化石为非洲爪蟾属的早期生物地理学和体型多样化提供了新信息。
Although the fossil record of pipoid frogs is more extensive than for other anuran clades, crown-group genera are poorly documented throughout the Cenozoic. We report an isolated neurocranium from the Nsungwe Formation (similar to 25 million years ago; Oligocene) in southwestern Tanzania, providing the earliest evidence for the genus Xenopus in sub-Saharan Africa. The specimen is well preserved, allowing us to use three-dimensional geometric morphometrics to compare the shape of this neurocranium to those of all extant species of Xenopus based on microcomputed tomography scans. Analyses revealed that this small fossil resembles diminutive extant species of Xenopus such as X. longipes. The fossil neurocranium preserves well-ossified tectum nasi and septum nasi, the latter separating large ovoid olfactory foramina, contributing to a more-ossified region surrounding the prootic foramen than observed in extant species of similar size. The Nsungwe Formation pipoid fossil contributes new information to the early biogeography and body-size diversification within the genus Xenopus.