论文标题：Fossil lemurs from Egypt and Kenya suggest an African origin for Madagascar’s aye-aye
By Erik R. Seiffert et al
Digital identification code: 10.1038/s41467-018-05648-w
A study recently published in Nature Communications, Fossil lemurs from Egypt and Kenya suggest an African origin for Madagascar's aye-aye-aye, once widely considered a fossil species of fruit bat, is actually a lemur of the monkey type, a close relative of the Malagasy finger monkey. On the basis of this reassessment, phylogenetic analysis showed that two lemur clades migrated independently from Africa to Madagascar, a result that challenges the currently accepted view that lemurs enter Madagascar only once.
Figure 1: Malagasy finger monkey. David Haring
In 1967, three mandibular faults found in sedimentary strata of the early Miocene (about 23-16 million years ago) in Kenya were classified as a new primate called Propotto leakeyi. However, this explanation was quickly refuted, with some pointing out that Propotto leakeyi was not a primate, but a fruit bat — a view that has not been questioned for more than half a century.
Figure 2: Madagascar refers to monkeys. David Haring
Erik Seiffert and colleagues at the University of Southern California in the United States found that Propotto leakeyi's teeth and fossils of the primate Plesiopithecus teras (a type of near-ape) found in Egypt about 34 million years ago: Propotto leakeyi is not only a primate, but also a close relative of Plesiopithecus teras and finger monkeys. The results of the study showed that the common ancestors of the order Lemur and the suborder Phalanx had African ancestry, and that the two lemur clades had crossed the Mozambique Strait along different paths and eventually reached Madagascar.
Figure 3: Comparison of mandibular molar morphology of Propotto, Plesiopithecus, and finger monkeys, and enlarged anterior teeth of Plesiopithecus and Propotto. Gunnell et al.
The authors note that their analysis is largely based on tooth morphology, so these hypotheses can only be further tested after newer, more complete fossil discoveries have been made.
摘要：In 1967 G.G. Simpson described three partial mandibles from early Miocene deposits in Kenya that he interpreted as belonging to a new strepsirrhine primate, Propotto. This interpretation was quickly challenged, with the assertion that Propotto was not a primate, but rather a pteropodid fruit bat. The latter interpretation has not been questioned for almost half a century. Here we re-evaluate the affinities of Propotto, drawing upon diverse lines of evidence to establish that this strange mammal is a strepsirrhine primate as originally suggested by Simpson. Moreover, our phylogenetic analyses support the recognition of Propotto, together with late Eocene Plesiopithecus from Egypt, as African stem chiromyiform lemurs that are exclusively related to the extant aye-aye (Daubentonia) from Madagascar. Our results challenge the long-held view that all lemurs are descended from a single ancient colonization of Madagascar, and present an intriguing alternative scenario in which two lemur lineages dispersed from Africa to Madagascar independently, possibly during the later Cenozoic.