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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.

Many discoveries in the life sciences have been made using material from living stock collections. These collections provide a uniform and stable supply of living organisms and related materials that enhance the reproducibility of research and minimize the need for repetitive calibration. While collections differ in many ways, they all require expertise in maintaining living organisms and good logistical systems for keeping track of stocks and fulfilling requests for specimens. Here, we review some of the contributions made by living stock collections to research across all branches of the tree of life, and outline the challenges they face.

The divergence of apes and Old World monkeys The primate fossil record is uneven, and substantial gaps remain. One gap is the divergence of cercopithecoids (Old World monkeys) and hominoids (apes and humans) within Old World higher primates (Catarrhini). This event was previously thought to have occurred sometime during the early Oligocene-early Miocene interval in Afro-Arabia, but the discovery of a new stem catarrhine in western Saudi Arabia narrows that gap. The Saudi specimen, dated to the mid-Oligocene around 29 million to 28 million years ago, shows no crown catarrhine specializations other than the presence of a tubular ectotympanic, suggesting that the divergence of Old World monkeys and apes happened after that date. The size of the cranium indicates a medium-sized primate, between 15 and 20 kilograms in body mass. The fossil record of primates is sparse, and many gaps remain in our knowledge. One gap relates to the divergence within the catarrhines -- the ancestors of hominoids (apes and humans) and Old World monkeys. The discovery of a previously unknown catarrhine in Saudi Arabia, dated to 29-28 million years ago, helps to fill in some details. This specimen shows very few catarrhine specializations, suggesting that the divergence between Old World monkeys and hominoids must have occurred after this date. It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys) have a common ancestry as Catarrhini deeply rooted in Afro-Arabia.sup.1,2,3,4. The oldest stem Catarrhini in the fossil record are Propliopithecoidea, known from the late Eocene to early Oligocene epochs (roughly 35-30 Myr ago) of Egypt, Oman and possibly Angola.sup.5,6,7,8,9,10. Genome-based estimates for divergence of hominoids and cercopithecoids range into the early Oligocene.sup.11; however, the mid-to-late Oligocene interval from 30 to 23 Myr ago has yielded little fossil evidence documenting the morphology of the last common ancestor of hominoids and cercopithecoids, the timing of their divergence, or the relationship of early stem and crown catarrhines. Here we describe the partial cranium of a new medium-sized (about 15-20 kg) fossil catarrhine, Saadanius hijazensis, dated to 29-28 Myr ago. Comparative anatomy and cladistic analysis shows that Saadanius is an advanced stem catarrhine close to the base of the hominoid-cercopithecoid clade. Saadanius is important for assessing competing hypotheses about the ancestral morphotype for crown catarrhines.sup.1,12,13,14, early catarrhine phylogeny.sup.12,15 and the age of hominoid-cercopithecoid divergence.sup.11. Saadanius has a tubular ectotympanic but lacks synapomorphies of either group of crown Catarrhini, and we infer that the hominoid-cercopithecoid split happened later, between 29-28 and 24 Myr ago., Author(s): Iyad S. Zalmout [sup.1] [sup.2] , William J. Sanders [sup.1] [sup.3] , Laura M. MacLatchy [sup.1] [sup.3] , Gregg F. Gunnell [sup.1] , Yahya A. Al-Mufarreh [sup.4] , Mohammad [...]

Bats (Chiroptera) represent one of the largest and most diverse radiations of mammals, accounting for one-fifth of extant species (1). Although recent studies unambiguously support bat monophyly (2-4) and consensus [...]