Palaeopropithecus kelyus (Lesser Sloth Lemur)

[Melanie]

ScienceDaily (May 27, 2009) — A third species of Palaeopropithecus, an extinct group of large lemurs, has just been uncovered in the northwest of Madagascar by a Franco-Madagascan team. Dubbed Palaeopropithecus kelyus, this new specimen is smaller than the two species of these 'large sloth lemurs' already known and its diet made up of harder-textured foodstuffs. This discovery supports the idea of a richer biodiversity in recent prehistory (late Pleistocene and beginning of the Holocene).

Madagascar, where natural environments show a high level of endemism, is one of the last great biodiversity sanctuaries in the world. The island is home to a special group of primates, the lemurs. There are presently 15 genera and 71 species of these small mammals on Madagascar.

The genus Palaeopropithecus is a group of subfossil giant lemurs(2). Up until now, two species had been described: P. ingens (in 1898) and P. maximus (in 1903). Palaeopropithecus have very specific adaptations, notably for locomotion, as they moved from branch to branch using all four limbs, with their head downwards, in a similar way to today's South American sloths.

Recent discoveries by the MAPPM(1) on sites in northwest Madagascar have established the existence of a third species of Palaeopropithecus, which has been dubbed P. kelyus. Scientists have suspected the existence of this species for more than 20 years. P. kelyus, whose weight is estimated around 35 kg, is smaller than the two known Palaeopropithecus species, but is very large in comparison with the largest living lemur, the Indri, which weighs only 10 kg.

The other main difference of this new species is that its teeth are smaller. Its dental characteristics could be described from the P. kelyus subfossil maxilla fragment, showing a crista obliqua, a parastyle and a highly developed mesostyle. This morphology is reminiscent of the present day Propithecus genus. While other Palaeopropithecus must have fed on leaves and fruit, the differences in the teeth of P. kelyus suggest that this animal could chew much tougher foods (notably seeds) compared with the other two known species. P. kelyus was found in an area of northwest Madagascar (Boeny region, Mahajanga province) with the particularity of being situated between large bays and rivers. This topography could have isolated P. kelyus from the other two species of Palaeopropithecus, one of which lived more in the south or centre, and the other in the north of Madagascar.

In the ‘evolution laboratory' that Madagascar represents, the discovery of this third Palaeopropithecus contributes to our understanding of the subfossil fauna species. More broadly, such work also includes the study of the island's human population.

(1) The project ‘Mission archéologique et paléontologique dans la province de Mahajanga' (MAPPM) is a Franco-Madagascan collaboration between CNRS UPR 2147 (Dynamique de l'Évolution Humaine: Individus, Populations, Espèces) and UFR Mozea Akiba of Université de Mahajanga, funded by the Sous-direction de l'archéologie et de la recherche en sciences sociales of the French Ministry of Foreign and European Affairs, CNRS and Université de Mahajanga.

(2) Subfossils are species that died out during the historic or prehistoric eras and overlapped present-day species. Unlike classic fossils, their bones are not completely mineralised.

The results, currently available online, will be published in the Comptes Rendus Palevol (Académie des Sciences), July-August 2009.

Journal reference:

1. Dominique Gommery, Beby Ramanivosoa, Sabine Tombomiadana-Raveloson, Hervé Randrianantenaina, Patrice Kerloc'h. Une nouvelle espèce de lémurien géant subfossile du Nord-Ouest de Madagascar (Palaeopropithecus kelyus, Primates). Comptes Rendus Palevol, 2009; DOI: 10.1016/j.crpv.2009.02.001

dx.doi.org/10.1016/j.crpv.2009.02.001

www.sciencedaily.com/releases/2009/05/090527073030.htm

[Melanie]

The remains of an extinct species of giant lemur were recently discovered in Madagascar, the first addition to the group in more than 100 years, according to a new report.

The species, Palaeopropithecus kelyus, confirms 20 years of speculation on its existence, said lead author Dominique Gommery, a paleontologist at the National Center for Scientific Research (CNRS) in Paris, France. Lemurs are a group of primates (which are mammals) that are found only in Madagascar. A total of 71 species of lemurs lives there.

P. kelyus is now the third member of a group of subfossil giant lemurs. Unlike classic fossils, subfossils are from bones of recently deceased species, and are only partially mineralized. The discovery may help scientists understand the evolutionary patterns in biodiversity hotspots such as Madagascar.

Giant lemurs have a tree-hopping motion that resembles that of South American sloths. They move from branch to branch using all four limbs, with their head downwards.

P. kelyus joins the two other species of giant lemur, P. ingens and P. maximus, which were discovered more than 100 years ago. P. kelyus is the smallest of the three giant lemurs, with an estimated weight of 77 pounds (35 kg). The largest living lemur, the Indri, weighs only 22 pounds (10 kg).

Small teeth and other dental features in the upper jaw distinguish P. kelyus from the other giant lemurs.

These features suggest that P. kelyus might have chewed tougher foods such as seeds. The other two giant lemurs are though to have fed mostly on leaves and fruit.

P. kelyus was discovered in northwest Madagascar, an area situated between large bays and rivers that may have isolated P. kelyus from the other giant lemurs.

The discovery project, dubbed Mission archéologique et paléontologique dans la province de Mahajanga (MAPPM), is a French and Malagasy collaboration. The findings are published online in the journal Comptes Rendus Palevol.

www.livescience.com/animals/090528-giant-lemur.html

[another specialist]

P.kelyus maxilla fragment, removed from its matrix. (Credit: Copyright D. Gommery- MAPPM & CNRS)

www.sciencedaily.com/releases/2009/05/090527073030.htm

[surroundx]

Russo, Gabrielle A. (2016). Comparative sacral morphology and the reconstructed tail lengths of five extinct primates: Proconsul heseloni, Epipliopithecus vindobonensis, Archaeolemur edwardsi, Megaladapis grandidieri, and Palaeopropithecus kelyus. Journal of Human Evolution 90: 135-162. [Abstract]

[Sebbe]

Subfossil lemur discoveries from the Beanka Protected Area in western Madagascar.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.

www.cambridge.org/core/journals/quaternary-research/article/subfossil-lemur-discoveries-from-the-beanka-protected-area-in-western-madagascar/FFF442F4FA0FDA35440158CFA3E97A8F

[Sebbe]

The macroevolutionary impact of recent and imminent mammal extinctions on Madagascar.

Many of Madagascar’s unique species are threatened with extinction. However, the severity of recent and potential extinctions in a global evolutionary context is unquantified. Here, we compile a phylogenetic dataset for the complete non-marine mammalian biota of Madagascar and estimate natural rates of extinction, colonization, and speciation. We measure how long it would take to restore Madagascar’s mammalian biodiversity under these rates, the “evolutionary return time” (ERT). At the time of human arrival there were approximately 250 species of mammals on Madagascar, resulting from 33 colonisation events (28 by bats), but at least 30 of these species have gone extinct since then. We show that the loss of currently threatened species would have a much deeper long-term impact than all the extinctions since human arrival. A return from current to pre-human diversity would take 1.6 million years (Myr) for bats, and 2.9 Myr for non-volant mammals. However, if species currently classified as threatened go extinct, the ERT rises to 2.9 Myr for bats and 23 Myr for non-volant mammals. Our results suggest that an extinction wave with deep evolutionary impact is imminent on Madagascar unless immediate conservation actions are taken.

www.nature.com/articles/s41467-022-35215-3