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1. Description of the subfossil crocodylians from a new Late Pleistocene subfossil site (Tsaramody, Sambaina Basin) in central Madagascar

   Rakotozandry, R.; Ranivoharimanana, L.; Ranaivosoa, V.; Rasolofomanana, N.; Hekkala, E.; Samonds, K.E. (December 2021, Malagasy nature)

   Madagascar is famous today not only for its unique biodiversity, but also for the high levels of endemism of plants and animals. Less appreciated is the fact that, in the recent past, the island had even greater biodiversity with many other endemic animals such as giant lemurs, elephant birds, pygmy hippopotami, tortoises, and crocodiles that have gone extinct within the past 2000 years. The extinction of many of these groups is thought to be the result of both human activities and environmental change. Most research has focused on the lemurs, hippopotami, and elephant birds. Other recently extinct animals, including the Malagasy horned crocodile (Voay robustus), are relatively poorly known. Madagascar’s subfossil crocodylians include two taxa: the extinct V. robustus (the Malagasy horned crocodile) and the extant Crocodylus niloticus. The latter arrived on Madagascar relatively recently and we know little about the habitat preferences, distributions and ecological interactions (if any) of either species during the Holocene. In order to better understand the recent history of crocodylian extinction in Madagascar, we must first identify which species were present and where they were found. We present here a description of subfossil crocodylian material collected from the newly discovered subfossil site of Tsaramody (Sambaina Basin), a high-elevation wetlandenvironment. At 1655 m, it represents the highest elevation subfossil site on the island. Here we describe both cranial (e.g., premaxillary, jugal, and squamosal “horns”) and postcranial elements (e.g., osteoderms). Our research indicates that crocodile material from Tsaramody appears morphologically to belong to V. robustus, the extinct species. However, oval tuberosities on the frontal bone and a triangular extension of the squamosal bone suggest previously unrecognized variation. 

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2. Subfossil birds from a submerged cave in southwestern Madagascar

   Rasolonjatovo, H.A M.; Muldoon, K.M.; Ranivoharimanana, L.; Rakotoarijaona, M.; Goodman, S. M. (December 2021, Malagasy nature)

   The Mahafaly karst of southwestern Madagascar is rich with subfossil deposits. Vintany Cave (also known as Aven Cave), a submerged cave at Tsimanampesotse National Park, is the most subfossil-dense submerged cave known in the world. In particular, the cave has yielded abundant remains of birds, including some that are extinct. Among 1077 bird specimens recovered under water from the cave floor and from excavated sediments at this site, 35 different taxa were identified. Taxonomic attributions were made through comparative morphological analysis, using comparative osteological museum collections. The majority of these species still occur inside the park. Five extinct taxa were recovered from the cave, including one species of elephant bird (Aepyornithidae, Mullerornis modestus), two species of giant endemic ground couas (Cuculidae, Coua cf. berthae and C. cf. primaeva), a shelduck (Alopochen sirabensis, Anatidae), and a lapwing (Charadriidae, Vanellus madagascariensis). Two extant taxa, Haliaeetus vociferoides (Accipitridae) and Threskiornis bernieri (Threskiornithidae) are locally extirpated, but exist at other localities in Madagascar. Remains of Greater Vasa Parrots (Psittaculidae, Coracopsis vasa) are predominant. Some of the identified extinct and locally extirpated taxa from Vintany Cave have an aquatic dependence, most specifically freshwater, that suggests that there has been environmental modification such as reduction of the important water sources in the region of Tsimanampesotse, and wetter conditions in the area in the past. 

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3. Evolutionary and phylogenetic insights from a nuclear genome sequence of the extinct, giant, “subfossil” koala lemur Megaladapis edwardsi

   https://doi.org/10.1073/pnas.2022117118  

   Marciniak, Stephanie; Mughal, Mehreen R.; Godfrey, Laurie R.; Bankoff, Richard J.; Randrianatoandro, Heritiana; Crowley, Brooke E.; Bergey, Christina M.; Muldoon, Kathleen M.; Randrianasy, Jeannot; Raharivololona, Brigitte M.; et al (June 2021, Proceedings of the National Academy of Sciences)

   No endemic Madagascar animal with body mass >10 kg survived a relatively recent wave of extinction on the island. From morphological and isotopic analyses of skeletal “subfossil” remains we can reconstruct some of the biology and behavioral ecology of giant lemurs (primates; up to ∼160 kg) and other extraordinary Malagasy megafauna that survived into the past millennium. Yet, much about the evolutionary biology of these now-extinct species remains unknown, along with persistent phylogenetic uncertainty in some cases. Thankfully, despite the challenges of DNA preservation in tropical and subtropical environments, technical advances have enabled the recovery of ancient DNA from some Malagasy subfossil specimens. Here, we present a nuclear genome sequence (∼2× coverage) for one of the largest extinct lemurs, the koala lemur Megaladapis edwardsi (∼85 kg). To support the testing of key phylogenetic and evolutionary hypotheses, we also generated high-coverage nuclear genomes for two extant lemurs, Eulemur rufifrons and Lepilemur mustelinus , and we aligned these sequences with previously published genomes for three other extant lemurs and 47 nonlemur vertebrates. Our phylogenetic results confirm that Megaladapis is most closely related to the extant Lemuridae (typified in our analysis by E. rufifrons ) to the exclusion of L. mustelinus , which contradicts morphology-based phylogenies. Our evolutionary analyses identified significant convergent evolution between M. edwardsi and an extant folivore (a colobine monkey) and an herbivore (horse) in genes encoding proteins that function in plant toxin biodegradation and nutrient absorption. These results suggest that koala lemurs were highly adapted to a leaf-based diet, which may also explain their convergent craniodental morphology with the small-bodied folivore Lepilemur . 

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4. THE JUVENILE CRANIUM AND UPPER DECIDUOUS DENTITION OF MEGALADAPIS MADAGASCARIENSIS (LEMUROIDEA, STRESIRRHINE, PRIMATES)

   Collins, Regan; Borths, Matthew R; Borrelli, Chiara (October 2023, Society of Vertebrate Paleontology)

   The living diversity of lemurs includes over 100 species spread across the diverse ecoregions of Madagascar. The late Pleistocene and Holocene subfossil record from Madagascar expands this diversity to include 17 extinct species, all larger than any extant lemur species. Numerous studies have explored this diversity by focusing on variation in life-history strategies in lemurs and other strepsirrhines, comparing them to haplorhine primates. In general, strepsirrhines gestate, wean, and reach sexual maturity more rapidly than haplorhines, but differences in relative brain size, body size, and ecology complicate these comparisons. Megaladapis madagascariensis is an extinct, large bodied (~46 kg) folivorous lemur that can provide an important point of reference in these studies, but early phases of M. madagascariensis ontogeny are necessary to develop these comparisons. Here, we describe a complete juvenile cranium of M. madagascariensis from Anjohibe cave in northern Madagascar. The specimen preserves the complete deciduous premolar row. MicroCT scans reveal the developing paracones of the canine, P2, and P3 are present in the crypts between the roots of the deciduous dentition. The crypt of M1 is preserved, though the crown is absent and the M1 alveoli are not fully developed. Using growth rate data collected from M. edwardsi dentition, the state of dental development in this specimen of M. madagascariensis suggests that it was less than one year-old at time of death. The entire cranium is about 55% the total length of an adult cranium from Anjohibe cave. As expected in such an immature individual, the rostrum is relatively short, post-orbital constriction is limited, and the nuchal crest is relatively small compared to the adult. This specimen also preserves an intact braincase, facilitating comparisons between the juvenile and adult endocasts from Megaladapis and extant lemurs at comparable developmental stages. Overall, the juvenile cranium supports previous observations that – adjusted for its large body mass – Megaladapis life history was consistent with the relatively accelerated life-history of other strepsirrhines. These observations provide important context and model parameters for exploring the impact of the very recent extinction of Megaladapis and other large bodied lemurs in Madagascar. 

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5. The growth and development of Pachylemur, a large-bodied lemurid,

   Rahantaharivao, N.J.; Godfrey, L.R.; Schwartz, G.T.; King, S.; Ranivoharimanana, L. (December 2021, Malagasy nature)

   As the largest-bodied member of the family Lemuridae and the presumed primary disperser of large seeds, Pachylemur, now extinct, was a critical member of Madagascar’s primate communities. Material of this genus has been found at almost all subfossil sites across Madagascar, but extensive samples of this taxon are known from very few. It has been one of the more historically neglected of the “giant” extinct lemurs, as it is not very different in morphology from its nearest extant relative, Varecia, except in body size. The flooded cave called Vintany at the Tsimanampesotse National Park in southwestern Madagascar has yielded numerous specimens of P. insignis, including whole skulls and mandibles, many isolated postcranial elements, and, importantly, partial associated skeletons of immature individuals. This material allows us to address previously unanswered questions regarding its paleobiology, including questions concerning its growth and development. This article focuses specifically on its life history profile (especially developmental sequences and life history-related traits such as Retzius line periodicity of the teeth and endocranial volume in adults). We ask to what extent, despite its larger size, did Pachylemur “grow” like its smaller-bodied relatives? Did its dental eruption sequence and index of Relative Retardation of the Replacement teeth resemble those of its closest relatives? Did it, like other lemurs, have a Retzius line periodicity that is lower than “expected” for a primate of its body size, and if so, what is the likely significance of this? Was its brain smaller than expected for a primate of its body size? For these and other questions, we evaluate how large-bodied lemurs differ from anthropoids of comparable body size. 

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