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93-478: This is an exceptionally wet area of Madagascar. The driest part of the year is from September to December. As the park is accessible only by a three-hour boat journey, the cyclone season (January to March) is best avoided. There are ten lemur species, including the red ruffed lemur , which is native to the peninsula. The island reserve of Nosy Mangabe is one of the best sites in Madagascar to try to glimpse

186-493: A prehensile tail , a trait found only in New World monkeys , particularly atelids , among primates. Lemurs also rely heavily on their sense of smell, a trait shared with most other mammals and early primates, but not with the visually oriented higher primates. This sense of smell is important in terms of marking territory as well as provide an indication of whether or not another lemur is a viable breeding partner. Lemurs are

279-493: A rhinarium (or "wet nose"); a fully functional vomeronasal organ , which detects pheromones ; a postorbital bar and the lack of postorbital closure (a wall of thin bone behind the eye); orbits (bony sockets that enclose the eye) that are not fully facing forward; left and right mandible (lower jaw) bones that are not fully fused; and a small brain-to-body mass ratio . Additional traits shared with other prosimian primates (strepsirrhine primates and tarsiers ) include

372-454: A tibia and two fibulae (lower leg bones) from a species of koala lemur ( Megaladapis grandidieri ) as belonging to Archaeoindris . Because of these misattributions and Lamberton's use of the immature bones, his reconstruction was inaccurate. In 1936, Alice Carleton corrected Lamberton by identifying the tibia and fibulae as belonging to a koala lemur. Carleton's corrections were later confirmed and other misattributions were corrected in

465-410: A bicornuate (two-horned) uterus and epitheliochorial placentation . Because their thumbs are only pseudo-opposable, making their movement less independent of the other fingers, their hands are less than perfect at grasping and manipulating objects. On their feet, they have a widely abducted hallux (first toe) which facilitates the grasping of tree limbs. A common misconception is that lemurs have

558-417: A damaged humerus (upper arm bone) and an almost complete femur (thigh bone). The other four come from an immature individual and include a damaged humerus, a damaged ulna (lower arm bone), and two femurs, both lacking the epiphyses (rounded end of the bone) on both ends. Archaeoindris is one of the least common of the subfossil lemurs, and the few known specimens were all found at Ampasambazimba in

651-452: A different ocean gyre , producing currents that ran counter to what they are today. The ocean currents were shown to be even stronger than today, which would have pushed a raft along faster, shortening the trip to 30 days or less—short enough for a small mammal to survive easily. As the continental plates drifted northward, the currents gradually changed, and by 20 mya the window for oceanic dispersal had closed, effectively isolating

744-479: A diverse group of primates in terms of morphology and physiology. Some lemurs, such as the sportive lemurs and indriids , have longer hind limbs than forelimbs , making them excellent leapers . Indriids also have a specialized digestive system for folivory , exhibiting enlarged salivary glands , a spacious stomach , and an elongated caecum (lower gut) that facilitates fermentation . The hairy-eared dwarf lemur ( Allocebus trichotis ) reportedly has

837-483: A few monotypic lemur taxa . Archaeoindris fontoynontii was first described by Herbert F. Standing in 1909 from two fragments of a maxilla (upper jaw) and a complete mandible (lower jaw). These type specimens —AM-6239 (maxillae) and AM-6237 (mandible)—are stored in the collection at the University of Antananarivo . The mandible contains a complete set of upper teeth, the left maxillary fragment contains

930-439: A four-tooth toothcomb due to the loss of either a pair of canines or incisors. Because the lower canine is either included in the toothcomb or lost, the lower dentition can be difficult to read, especially since the first premolar (P2) is often shaped like a canine (caniniform) to fill the canine's role. In folivorous (leaf-eating) lemurs, except for indriids, the upper incisors are greatly reduced or absent. Used together with

1023-474: A functional strepsirrhine toothcomb. In the case of the aye-aye, the morphology of the deciduous incisors, which are lost shortly after birth, indicates that its ancestors had a toothcomb. These milk teeth are lost shortly after birth and are replaced by open-rooted, continually growing ( hypselodont ) incisors. The toothcomb in lemurs normally consists of six teeth (four incisors and two canines), although indriids, monkey lemurs, and some sloth lemurs only have

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1116-416: A great size difference. Lamberton was also persuaded by the size difference, partly because he failed to recognize the smaller tibia and fibulae as belonging to the smaller Megaladapis grandidieri . Furthermore, Lamberton did not realize that the smaller femurs he assigned to Archaeoindris belonged to a juvenile. Although some later authors considered Lemuridotherium a synonym of Archaeoindris , it

1209-487: A highly mobile, filiform (filament-shaped) middle finger for extracting food from tiny holes; large, bat -like ears for detecting hollow spaces within trees; and use of self-generated acoustical cues to forage. Lemurs are unusual since they have great variability in their social structure, yet generally lack sexual dimorphism in size and canine tooth morphology. However, some species tend towards having larger females, and two species of true lemur (genus Eulemur ),

1302-428: A juvenile and a massive adult leg bone were erroneously assumed to belong to two separate species. These errors were gradually corrected between the 1930s and 1980s. The skeleton of Archaeoindris was massive and robust, and shared many traits with that of Palaeopropithecus . The arms were longer than the legs, but no hand or foot bones have been found for comparison with the other sloth lemurs. Size estimates based on

1395-434: A low, broad sagittal crest (a ridge of bone on the top of the skull to which jaw muscles attach) and robust but smaller nuchal crests (ridges of bone on the back of the skull to which neck muscles attach). The rims of the orbits (eye sockets) were not as thick as those of Palaeopropithecus . The area of the orbit was 946 mm (1.466 sq in), comparable to that of gorillas. The ratio of its orbit area to

1488-427: A mass of 230.5 kg (508 lb), while the femoral head diameter predicted a mass of 244.1 kg (538 lb). In 1995, Laurie Godfrey estimated a mass of 197.5 kg (435 lb) using the midshaft circumferences of the humerus and femur. Using multiple regressions of the cortical area of the femur in 2008, Jungers and colleagues generated the current best estimate of 161.2 kg (355 lb) with

1581-435: A more thorough analysis. Lemurs vary greatly in size. They include the smallest primates in the world and, until recently, also included some of the largest. They currently range in size from about 30 g (1.1 oz) for Madame Berthe's mouse lemur ( Microcebus berthae ) up to 7–9 kg (15–20 lb) for the indri ( Indri indri ) and diademed sifaka ( Propithecus diadema ). One recently extinct species rivaled

1674-410: A possible range of 150–187.8 kg (331–414 lb). These estimates were considered to be more accurate since the harder cortical bone in the midshaft of the femur supported an animal's weight, and its thickness better correlated with the animal's mass than the midshaft diameter (which includes both hard cortex and spongy bone ). The only fossil primate that was probably larger than Archaeoindris

1767-407: A slow-moving tree-dweller like Megaladapis , primarily due to the misattributed bones. Lamberton also speculated that it would have resembled a ground sloth—a view later supported by Jungers in 1980 after several misattributions had been corrected and having considered its gorilla-like size. Jungers went on to propose that it would have spent most of its time on the ground ( terrestrial ). However,

1860-415: A very long tongue , allowing it to feed on nectar . Likewise, the red-bellied lemur ( Eulemur rubriventer ) has a feathery brush-shaped tongue, also uniquely adapted to feed on nectar and pollen. The aye-aye has evolved some traits that are unique among primates, making it stand out among the lemurs. Such traits include continuously growing, rodent-like front teeth for gnawing through wood and hard seeds;

1953-435: A wide variety of fruits and leaves, while some are specialists. Two species of lemurs may coexist in the same forest due to different diets. Lemur research during the 18th and 19th centuries focused on taxonomy and specimen collection. Modern studies of lemur ecology and behavior did not begin in earnest until the 1950s and 1960s. Initially hindered by political issues on Madagascar during the mid-1970s, field studies resumed in

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2046-408: Is an extinct giant lemur and the largest primate known to have evolved on Madagascar , comparable in size to a male gorilla . It belonged to a family of extinct lemurs known as " sloth lemurs " (Palaeopropithecidae) and, because of its extremely large size, it has been compared to the ground sloths that once roamed North and South America. It was most closely related to Palaeopropithecus ,

2139-659: Is basal to all Lemuriformes, and in 2008, Russell Mittermeier, Colin Groves, and others ignored addressing higher-level taxonomy by defining lemurs as monophyletic and containing five living families, including Daubentoniidae. Relationships among lemur families have also proven to be problematic and have yet to be definitively resolved. To further complicate the issue, several Paleogene fossil primates from outside Madagascar, such as Bugtilemur , have been classified as lemurs. However, scientific consensus does not accept these assignments based on genetic evidence, and therefore it

2232-742: Is endemic to the park. Three marine parks are included in the Masoala National Park: Tampolo in the West, Ambodilaitry in the South, and Ifaho in the East. These are among the most diverse marine environments in Madagascar and are superb destinations for kayaking and snorkeling . Each year from July to early September, hundreds of humpback whales visit the Antongil Bay during their long migration. The warm protected waters of

2325-600: Is generally accepted that the Malagasy primates are monophyletic. Another area of contention is the relationship between the sportive lemurs and the extinct koala lemurs (Megaladapidae). Formerly grouped in the same family due to similarities in dentition, they are no longer considered to be closely related due to genetic studies. More taxonomic changes have occurred at the genus level, although these revisions have proven more conclusive, often supported by genetic and molecular analysis. The most noticeable revisions included

2418-670: Is highest in the rainforests of the east coast. Despite their adaptations for weathering extreme adversity, habitat destruction and hunting have resulted in lemur populations declining sharply, and their diversity has diminished, with the recent extinction of at least 17 species in eight genera, known collectively as the subfossil lemurs . Most of the approximately 100 species and subspecies of lemur are either threatened or endangered. Unless trends change, extinctions are likely to continue. Until recently, giant lemurs existed on Madagascar. Now represented only by recent or subfossil remains, they were modern forms that were once part of

2511-516: Is now used in the colloquial sense in reference to all Malagasy primates. Lemur taxonomy is controversial, and not all experts agree, particularly with the recent increase in the number of recognized species. According to Russell Mittermeier , the president of Conservation International (CI), taxonomist Colin Groves , and others, there are nearly 100 recognized species or subspecies of extant (or living) lemur, divided into five families and 15 genera. Because genetic data indicates that

2604-506: Is smaller than that of anthropoid primates. As with all strepsirrhine primates, they have a "wet nose" ( rhinarium ). Lemurs are generally the most social of the strepsirrhine primates, living in groups known as troops. They communicate more with scents and vocalizations than with visual signals. Lemurs have a relatively low basal metabolic rate , and as a result may exhibit dormancy such as hibernation or torpor . They also have seasonal breeding and female social dominance . Most eat

2697-577: Is supported by data from morphological , developmental , and molecular research. Another member of this clade (related group) is the family of monkey lemurs (Archaeolemuridae). Dental features, such as the morphology of their molar teeth and the modified number of teeth in their toothcomb (a specialized grooming structure found in lemuriforms), have long suggested a relationship. However, other anatomical and developmental traits suggested that monkey lemurs might be more closely related to family Lemuridae , which include five genera of lemur, including

2790-488: Is unknown whether it was like Palaeopropithecus in performing hang-feeding since hand and foot bones are missing. Given its bulky size, this would be unexpected. Archaeoindris is known from only one subfossil site, Ampasambazimba, in central Madagascar, and all remains date to the Late Quaternary . The area today is dominated by grasslands, particularly of the grass genus Aristida . Prior to human arrival,

2883-547: The Central Highlands . Excavations run by a multi-disciplinary Malagasy-American team at this fossil site between 1983 and 1984 yielded no new subfossil remains , and no other potential sites are known for this species. Historically, some remains from other subfossil lemurs have been mistakenly attributed to Archaeoindris , resulting in incorrect interpretations of its anatomy and behavior. In 1934, Lamberton missed earlier attribution errors and incorrectly labeled

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2976-508: The Eocene (56 to 34  mya ) or Paleocene (66 to 56 mya). Adapiforms, however, lack a specialized arrangement of teeth, known as a toothcomb , which nearly all living strepsirrhines possess. A more recent hypothesis is that lemurs descended from lorisoids (loris-like) primates. This is supported by comparative studies of the cytochrome b gene and the presence of the strepsirrhine toothcomb in both groups. Instead of being

3069-666: The International Union for Conservation of Nature (IUCN) considers lemurs to be the world's most endangered mammals, noting that as of 2013 up to 90% of all lemur species confront the threat of extinction in the wild within the next 20 to 25 years. Ring-tailed lemurs are an iconic flagship species . Collectively, lemurs exemplify the biodiverse fauna of Madagascar and have facilitated the emergence of eco-tourism . In addition, conservation organizations increasingly seek to implement community-based approaches to save lemur species and promote sustainability. Carl Linnaeus ,

3162-591: The Mozambique Channel , a deep channel between Africa and Madagascar with a minimum width of about 560 km (350 mi). In 1915, paleontologist William Diller Matthew noted that the mammalian biodiversity on Madagascar (including lemurs) can only be accounted for by random rafting events , where very small populations rafted from nearby Africa on tangled mats of vegetation, which get flushed out to sea from major rivers. This form of biological dispersal can occur randomly over millions of years. In

3255-471: The gorilla in size, at 160–200 kg (350–440 lb) for Archaeoindris fontoynonti . Like all primates, lemurs have five divergent digits with nails (in most cases) on their hands and feet. Most lemurs possess a laterally compressed, elongated nail, called a toilet-claw , on the second toe and use it for scratching and grooming. In addition to the toilet-claw, lemurs share a variety of other traits with other strepsirrhine primates, which include

3348-416: The gray-headed lemur ( E. albocollaris ) and the red lemur ( E. rufus ), exhibit size differences in canine teeth. True lemurs show sexual dichromatism (sexual differences in fur coloration), but the difference between the genders varies from strikingly obvious, as in the blue-eyed black lemur ( E. macaco ), to nearly imperceptible in the case of the common brown lemur ( E. fulvus ). Crypsis , or

3441-453: The postcranium (skeleton below the skull) indicate that Babakotia was the next most closely related sloth lemur to Archaeoindris and Palaeopropithecus , followed by Mesopropithecus , the smallest of the sloth lemurs. All four genera of sloth lemurs are known to be a sister taxon (close relatives) of family Indriidae , which includes the indri ( Indri ), sifakas ( Propithecus ), and woolly lemurs ( Avahi ). This relationship

3534-428: The ring-tailed lemur ( Lemur catta ). Molecular analysis has shown strong support for the former, placing the monkey lemurs in a clade with the sloth lemurs and indriids. The family Palaeopropithecidae contained a large number of species compared to most other subfossil lemur families. It included four known genera and seven species, all of which are now extinct. Among these was the genus Archaeoindris , one of only

3627-449: The toothcomb of most lemurs, the bottom incisors and canine teeth are procumbent (face forward rather than up) and finely spaced, thus providing a tool for either grooming or feeding. For instance, indri use their toothcomb not only for grooming, but also to pry out the large seeds from the tough epicarp of Beilschmiedia fruits, while fork-marked lemurs use their relatively long toothcomb to cut through tree bark to induce

3720-525: The 1940s, American paleontologist George Gaylord Simpson coined the term "sweepstakes hypothesis" for such random events. Rafting has since been the most accepted explanation for the lemur colonization of Madagascar, but until recently, this trip was thought to be very unlikely because strong ocean currents flow away from the island. In January 2010 , a report demonstrated that around 60 mya both Madagascar and Africa were 1,650 km (1,030 mi) south of their present-day positions, placing them in

3813-419: The 1960s and 1970s by Alan Walker and William L. Jungers . In 1910, twenty-four years before Lamberton's monograph on Archaeoindris , Standing identified a massive right femur from Ampasambazimba as a new species, Lemuridotherium madagascariense . Although Standing recognized the strong similarities between Lemuridotherium and Archaeoindris , he placed them in separate genera due to what he perceived as

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3906-709: The 1980s. Lemurs are important for research because their mix of ancestral characteristics and traits shared with anthropoid primates can yield insights on primate and human evolution . Most species have been discovered or promoted to full species status since the 1990s; however, lemur taxonomic classification is controversial and depends on which species concept is used. Many lemur species remain endangered due to habitat loss and hunting. Although local traditions, such as fady , generally help protect lemurs and their forests, illegal logging , economic privation and political instability conspire to thwart conservation efforts. Because of these threats and their declining numbers,

3999-482: The 30-gram (1.1 oz) mouse lemur to the 9-kilogram (20 lb) indri . Since the arrival of humans on the island around 2,000 years ago, over a dozen species of " giant lemurs " larger than living lemur species have become extinct, including the gorilla-sized Archaeoindris . Lemurs share many common basal primate traits, such as divergent digits on their hands and feet, and nails instead of claws (in most species). However, their brain-to-body size ratio

4092-417: The adjacent image. Lemur taxonomy has changed significantly since the first taxonomic classification of lemurs by Carl Linnaeus in 1758. One of the greatest challenges has been the classification of the aye-aye, which has been a topic of debate up until very recently. Until Richard Owen published a definitive anatomical study in 1866, early naturalists were uncertain whether the aye-aye (genus Daubentonia )

4185-443: The area around Ampasambazimba was not completely forested, but more of an open habitat, consisting of a mix of woodlands, bushlands, and savanna. Animal remains at this subfossil site have yielded about 20 species of lemur living in sympatry (sharing the same geographic area). In comparison, the nearby Ambohitantely Special Reserve today contains only four species, roughly 20% of the area's original lemur diversity. Despite being

4278-468: The arrival of humans roughly 1500 to 2000 years ago, lemurs were found all across the island. However, early settlers quickly converted the forests to rice paddies and grassland through slash-and-burn agriculture (known locally as tavy ), restricting lemurs to approximately 10% of the island's area, ~60,000 km (23,000 sq mi). Today, the diversity and complexity of lemur communities increases with floral diversity and precipitation and

4371-526: The aye-aye, and the extinct sloth lemurs , monkey lemurs , and koala lemurs have reduced dentitions, having lost incisors, canines, or premolars. The ancestral deciduous dentition is 2.1.3 2.1.3 , but young indriids, aye-ayes, koala lemurs, sloth lemurs, and probably monkey lemurs have fewer deciduous teeth. There are also noticeable differences in dental morphology and tooth topography between lemurs. Indri , for instance, have teeth that are perfectly adapted for shearing leaves and crushing seeds. In

4464-529: The basis of subfossil fragmentary jaws, although Charles Lamberton later discovered a complete skull. Only six bones from the lower skeleton have been found and excavations in the 1980s offered no leads for new finds. Its remains have been found at only one location: Ampasambazimba , a subfossil site in central Madagascar. Following its initial discovery, some subfossil remains of Megaladapis grandidieri (a type of extinct koala lemur ) were mistakenly associated with Archaeoindris , while smaller leg bones from

4557-492: The bay provide an ideal breeding and calving ground for these marine mammals. In June 2007, Masoala was designated as a World Heritage Site as part of a cluster of parks, known collectively as Rainforests of the Atsinanana , that represent the biodiversity of the country's eastern rainforests. The other national parks included are Marojejy , Zahamena , Ranomafana , Andringitra , and Andohahela . During 2009 and 2010,

4650-455: The case of mouse lemurs, the gray mouse lemur ( M. murinus ), golden-brown mouse lemur ( M. ravelobensis ), and Goodman's mouse lemur ( M. lehilahytsara ) were considered the same species until recently, when genetic tests identified them as cryptic species. The lemur dentition is heterodont (having multiple tooth morphologies) and derives from an ancestral primate permanent dentition of 2.1.3.3 2.1.3.3 . Indriids, sportive lemurs,

4743-508: The direct ancestors of lemurs, the adapiforms may have given rise to both the lemurs and lorisoids, a split that would be supported by molecular phylogenetic studies. The later split between lemurs and lorises is thought to have occurred approximately 62 to 65 mya according to molecular studies, although other genetic tests and the fossil record in Africa suggest more conservative estimates of 50 to 55 mya for this divergence. However,

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4836-572: The elusive nocturnal aye-aye . Masoala harbors many other species, such as the Madagascar day gecko , leaf-tailed gecko , chameleons of all sizes, spectacular birds such as the helmet vanga , and rare species such as the red owl and tomato frog . Masoala is also home to the day-flying sunset moth, Chrysiridia rhipheus . The Madagascar serpent-eagle was recently rediscovered here, and exists in healthy populations only in this part of northeast Madagascar. The tree Ephippiandra masoalensis

4929-564: The environment. Lemurs have adapted to fill many open ecological niches since making their way to Madagascar. Their diversity in both behavior and morphology (outward appearance) rivals that of the monkeys and apes found elsewhere in the world. Ranging in size from the 30 g (1.1 oz) Madame Berthe's mouse lemur , the world's smallest primate, to the recently extinct 160–200 kg (350–440 lb) Archaeoindris fontoynonti , lemurs evolved diverse forms of locomotion, varying levels of social complexity, and unique adaptations to

5022-471: The extinct giant ground sloths of North and South America. † Archaeolemur † Hadropithecus † Mesopropithecus † Babakotia † Palaeopropithecus † Archaeoindris Indri ( indri ) Propithecus ( sifakas ) Avahi ( woolly lemurs ) Archaeoindris was most closely related to Palaeopropithecus , a genus containing the second largest of the sloth lemurs and specialized for suspensory behavior in its arboreal habitat. Traits of

5115-424: The femur was large and lacked a fovea capitis femoris (a small depression in the head of the femur). The femur was short and extremely robust, had a very high collodiaphyseal angle (the angle of the neck and shaft of the bone), and the greater trochanter was small. In the adult, the humerus was significantly longer than the femur, while in the immature specimen, both the humerus and ulna were much longer than

5208-557: The femur, making the arms considerably longer than the legs, as also seen in Palaeopropithecus . Yet, the relative length of arms to legs was shorter in Archaeoindris , so although its intermembral index was over 100, it was lower than that of Palaeopropithecus . Archaeoindris is thought to have been a leaf-eater ( folivorous ), a view supported by wear patterns on its teeth. Its fused mandibular symphyses and

5301-416: The flow of tree sap . The toothcomb is kept clean by the sublingua or "under-tongue", a specialized structure that acts like a toothbrush to remove hair and other debris. The sublingua extends below the tip of the tongue and is tipped with keratinized , serrated points that rake between the front teeth. Only the aye-aye, the extinct giant aye-aye , and the largest of the extinct giant sloth lemurs lack

5394-472: The founder of modern binomial nomenclature , gave lemurs their name as early as 1758. With his declaration of the genus Lemur in the 10th edition of Systema Naturae , he included three species: Lemur tardigradus (the red slender loris , now known as Loris tardigradus ), Lemur catta (the ring-tailed lemur ), and Lemur volans (the Philippine colugo , now known as Cynocephalus volans ). Although

5487-421: The full range of lemur sizes. Daubentoniidae Lemuridae Indriidae Lepilemuridae Cheirogaleidae Daubentoniidae Lepilemuridae Cheirogaleidae Lemuridae † Megaladapidae Indriidae † Palaeopropithecidae † Archaeolemuridae From a taxonomic standpoint, the term "lemur" originally referred to the genus Lemur , which currently contains only the ring-tailed lemur . The term

5580-435: The functional morphology of its hip joint indicates a degree of mobility typically seen in more arboreal animals. Other traits shared with Palaeopropithecus , particularly seen in the femur, suggest that Archaeoindris spent considerable time in the trees for feeding and possibly nesting, although it also would have visited the ground to feed and travel. It is described as a deliberate, scansorial (climbing) browser , and it

5673-550: The gradual split of a broadly defined genus Lemur into separate genera for the ring-tailed lemur , ruffed lemurs , and brown lemurs due to a host of morphological differences. Due to several taxonomic revisions by Russell Mittermeier, Colin Groves, and others, the number of recognized lemur species has grown from 33 species and subspecies in 1994 to approximately 100 in 2008. With continuing cytogenetic and molecular genetic research, as well as ongoing field studies , particularly with cryptic species such as mouse lemurs,

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5766-425: The inability of humans to visually distinguish between two or more distinct species, has recently been discovered among lemurs, particularly within the sportive lemurs ( Lepilemur ) and mouse lemurs ( Microcebus ). With sportive lemurs, subspecies were traditionally defined based on slight morphological differences, but new genetic evidence has supported giving full species status to these regional populations. In

5859-456: The island of Madagascar . Most existing lemurs are small, have a pointed snout, large eyes, and a long tail. They chiefly live in trees and are active at night . Lemurs share resemblance with other primates , but evolved independently from monkeys and apes . Due to Madagascar's highly seasonal climate, lemur evolution has produced a level of species diversity rivaling that of any other primate group. Living lemurs range in weight from

5952-584: The last premolar (P4) and all three molars (M1–M3), and the right maxillary fragment bears both premolars (P2 and P4) and the first molar (M1). At the time, Standing noted similarities with the dentition of Palaeopropithecus . Sixteen years after Standing's discovery, Charles Lamberton discovered the first and only complete cranium (skull) and associated mandible for Archaeoindris , both of which were well preserved. He published this find in 1934. Only six postcranial specimens of Archaeoindris have been found. Two of these belonged to an adult and include

6045-460: The lemurs and the rest of the terrestrial Malagasy fauna from mainland Africa. Isolated on Madagascar with only a limited number of mammalian competitors, the lemurs did not have to compete with other evolving arboreal mammalian groups, such as squirrels . They were also spared from having to compete with monkeys , which evolved later. The intelligence, aggression, and deceptiveness of monkeys gave them an advantage over other primates in exploiting

6138-419: The likelihood of accelerated dental development suggest that it began processing fibrous foods in the mouth with thorough chewing. Its diet may also have included some fruits and seeds. Like most of the other giant lemurs, Archaeoindris is thought to have been diurnal because of its relatively small orbits, which are comparable to those of gorillas. Both Standing and Lamberton assumed Archaeoindris to be

6231-409: The limited remains have varied widely, ranging as high as 244 kilograms (538 pounds), but the most thorough statistical investigation using regression analyses predicts a mass of 160 kg (350 lb). Misattributions and limited remains have resulted in varying opinions about the way Archaeoindris moved in its environment, ranging from tree-dwelling to ground-dwelling. Its skeleton suggests it

6324-769: The local climate. Lemurs lack any shared traits that make them stand out from all other primates. Different types of lemurs have evolved unique combinations of unusual traits to cope with Madagascar's harsh, seasonal climate. These traits can include seasonal fat storage, hypometabolism (including torpor and hibernation ), small group sizes, low encephalization (relative brain size), cathemerality (activity both day and night), and strict breeding seasons . Extreme resource limitations and seasonal breeding are also thought to have given rise to three other relatively common lemur traits: female social dominance , sexual monomorphism, and male–male competition for mates involving low levels of agonism , such as sperm competition . Before

6417-425: The most species-rich family among the giant lemurs, all four genera of sloth lemur, including Archaeoindris , have gone extinct. Radiocarbon dating of the stratigraphic level of some of the Archaeoindris remains were dated to 8000  BP , while two other specimens were dated to 2362–2149 BP (412–199  BCE ) and 2711–2338 BP (761–388 BCE). From these dates, it is likely that Archaeoindris

6510-496: The national park was invaded by thousands of illegal loggers searching for rosewood. Lemur Lemurs ( / ˈ l iː m ər / LEE -mər ; from Latin lemures lit.   ' ghosts ' or ' spirits ' ) are wet-nosed primates of the superfamily Lemuroidea ( / l ɛ m j ʊ ˈ r ɔɪ d i ə / lem-yuurr- OY -dee-ə ), divided into 8 families and consisting of 15 genera and around 100 existing species . They are endemic to

6603-445: The number of recognized lemur species is likely to keep growing. However, the rapid increase in the number of recognized species has had its critics among taxonomists and lemur researchers. Since classifications ultimately depend on the species concept used, conservationists often favor definitions that result in the splitting of genetically distinct populations into separate species to gain added environmental protection. Others favor

6696-492: The oldest lemur fossils on Madagascar are actually subfossils dating to the Late Pleistocene . Once part of the supercontinent Gondwana , the island of Madagascar has been isolated since it broke away from eastern Africa (~160 mya), Antarctica (~80–130 mya), and India (~80–90 mya). Since ancestral lemurs are thought to have originated in Africa around 62 to 65 mya, they must have crossed

6789-503: The president of the Académie Malgache ( Malagasy Academy ) at the time. Fontoynont was reported to have been supervising the excavation when it was discovered. Archaeoindris was a type of sloth lemur (family Palaeopropithecidae), a recently extinct family of giant lemurs (known as subfossil lemurs ) native to Madagascar . Its ancestors were likely arboreal (tree-dwelling), and this giant sloth lemur has been compared to

6882-417: The recently extinct subfossil lemurs were closely related to living lemurs, an additional three families, eight genera, and 17 species can be included in the total. In contrast, other experts have labeled this as taxonomic inflation , instead preferring a total closer to 50 species. The classification of lemurs within the suborder Strepsirrhini is equally controversial, although most experts agree on

6975-679: The rest of the lemurs were placed in Lemuriformes and the lorisoids in Lorisiformes. Although it is generally agreed that the aye-aye is the most basal member of the lemur clade, the relationship between the other four families is less clear since they diverged during a narrow 10 to 12 million-year window between the Late Eocene (42 mya) and into the Oligocene (30 mya). The two main competing hypotheses are shown in

7068-640: The rich lemur diversity that has evolved in isolation. Some of their adaptations were unlike those seen in their living relatives. All 17 extinct lemurs were larger than the extant (living) forms, some weighing as much as 200 kg (440 lb), and are thought to have been active during the day. Not only were they unlike the living lemurs in both size and appearance, they also filled ecological niches that either no longer exist or are now left unoccupied. Large parts of Madagascar, which are now devoid of forests and lemurs, once hosted diverse primate communities that included more than 20 lemur species covering

7161-451: The same phylogenetic tree . In one taxonomy, the infraorder Lemuriformes contains all living strepsirrhines in two superfamilies, Lemuroidea for all lemurs and Lorisoidea for the lorisoids ( lorisids and galagos). Alternatively, the lorisoids are sometimes placed in their own infraorder, Lorisiformes, separate from the lemurs. In another taxonomy published by Colin Groves, the aye-aye was placed in its own infraorder, Chiromyiformes, while

7254-438: The second largest type of sloth lemur. Along with the other sloth lemurs, Archaeoindris was related to the living indri , sifakas , and woolly lemurs , as well as the recently extinct monkey lemurs (Archaeolemuridae). The genus , Archaeoindris , translates to "ancient indri-like lemur", even though it probably became extinct recently, around 350 BCE . Archaeoindris was first described by Herbert F. Standing in 1909 on

7347-403: The size of its optic canal indicates that Archaeoindris had low retinal summation , meaning its eyes were as sensitive to light as those of living diurnal lemurs. Yet the ratio was not as low as in comparably sized apes, suggesting Archaeoindris had lower visual acuity than apes do and lacked trichromatic color vision . The jaw exhibited a long, robust mandibular symphysis (joining of

7440-608: The term lemur was first intended for slender lorises , it was soon limited to the endemic Malagasy primates, which have been known as collectively "lemurs" ever since. The name lemur is derived from the Latin term lemures , which refers to specters or ghosts that were exorcised during the Lemuria festival of ancient Rome. Linnaeus was familiar with the works of Virgil and Ovid , both of whom mentioned lemures. Seeing an analogy that fit with his naming scheme, he adapted

7533-906: The term lemur was selected because of the nocturnal activity and slow movements of the red slender loris: Lemures dixi hos, quod noctu imprimis obambulant, hominibus quodanmodo similes, & lento passu vagantur. I call them lemurs, because they go around mainly by night, in a certain way similar to humans, and roam with a slow pace. Lemurs are primates belonging to the suborder Strepsirrhini . Like other strepsirrhine primates , such as lorises , pottos , and galagos , they share ancestral (or plesiomorphic ) traits with early primates. In this regard, lemurs are popularly confused with ancestral primates; however, lemurs did not give rise to monkeys and apes ( simians ). Instead, they evolved independently in isolation on Madagascar . All modern strepsirrhines including lemurs are traditionally thought to have evolved from early primates known as adapiforms during

7626-515: The term "lemur" for these nocturnal primates. It was noted in 2012 that many sources had commonly and falsely assumed that Linnaeus was referring to the ghost-like appearance, reflective eyes , and ghostly cries of Madagascar's lemurs when he selected the name. Up until then, it had also been speculated that Linnaeus may also have known that some Malagasy people believed that lemurs were the souls of their ancestors . However, both claims were discredited since according to Linnaeus' own explanation,

7719-668: The toothcomb on the mandible (lower jaw), this complex is reminiscent of an ungulate browsing pad . Lemurs are unusual among primates for their rapid dental development, particularly among the largest species. For example, indriids have relatively slow body growth but extremely fast tooth formation and eruption . By contrast, anthropoid primates exhibit slower dental development with increased size and slower morphological development. Lemurs are also dentally precocious at birth, and have their full permanent dentition at weaning . Archaeoindris Lemuridotherium madagascariense Standing, 1910 Archaeoindris fontoynontii

7812-409: The toothcomb were modified, being shorter and more robust, possibly for feeding purposes. The canines were short and stout, but sharp. Also, there was a diastema (gap) between the lower premolars (p2 and p4). Other dental similarities with Palaeopropithecus included small third upper and lower molars (M3 and m3), the first and second molars were narrow and long, and the enamel of its cheek teeth

7905-425: The two halves of the lower jaw), which fused early during development. Its palate (bones on the roof of the mouth) was rectangular. Like other sloth lemurs, it likely experienced accelerated dental development, and had an adult dental formula of 2.1.2.3 2.0.2.3 . Its teeth were also similar to those of Palaeopropithecus , both in morphology and proportions. The four lower incisors that would have made up

7998-405: Was Gigantopithecus blacki , a close relative of orangutans . Like all three species of Palaeopropithecus , Archaeoindris exhibited derived traits not seen in the two other less specialized genera of sloth lemur. These traits included deflated auditory bullae and paired protrusions of bone around the nasal opening consisting of part of the premaxilla and the nasal bones . Its skull

8091-416: Was a primate , rodent , or marsupial . However, the placement of the aye-aye within the order Primates remained problematic until very recently. Based on its anatomy, researchers have found support for classifying the genus Daubentonia as a specialized indriid , a sister group to all strepsirrhines, and as an indeterminate taxon within the order Primates. Molecular tests have now shown Daubentoniidae

8184-403: Was a deliberate climber that visited the ground to travel. The diet of Archaeoindris was mostly leaves, and its habitat—prior to human arrival—was a mix of woodlands , bushlands, and savanna , rich in lemur diversity. Today, the region is dominated by grasslands and lemur diversity is very low in the nearest protected area , Ambohitantely Special Reserve . Although it was a rare lemur, it

8277-459: Was crenulated (low and rounded), though not as wrinkled and slightly higher- crowned . Most bones of the postcranial skeleton, including the bones of the hands, feet, vertebral column, ribs, radius (lower arm bone), tibia, and fibula, have not been found for Archaeoindris . As with many cranial features, the postcranial bones that have been discovered are similar to that of Palaeopropithecus , but significantly larger and more robust. The head of

8370-451: Was not until 1988 that Martine Vuillaume-Randriamanantena provided a definitive proof. Vuillaume-Randriamanantena also established associations between the postcrania and crania of Archaeoindris , summarized what is known about the postcranial skeleton, and documented the strong similarity with the genus Palaeopropithecus . Though similar to Palaeopropithecus , Archaeoindris was significantly larger and more robust. Archaeoindris

8463-424: Was one of the largest primates to ever evolve, and was the largest-known strepsirrhine primate, weighing an estimated 160 kg (350 lb). It was roughly the size of an adult male gorilla, which was first noted by Lamberton. Since its discovery, size estimates have varied from "larger than a human" to "possibly the largest primate ever". In a study by Jungers from 1990, the area of its molar teeth predicted

8556-501: Was still extant when humans first arrived on Madagascar , and it would have been vulnerable to hunting and habitat loss . The generic name Archaeoindris , meaning "ancient indri-like lemur", is derived from the Greek word ἀρχαῖος (archaios, or "ancient") and indris , a common variation of the generic name Indri . The species name, fontoynontii (sometimes spelled fontoynonti ), was selected in honor of Antoine Maurice Fontoynont,

8649-405: Was wider than that of Megaladapis , but shorter, measuring 269 millimeters (10.6 inches). Its face was shorter than that of Palaeopropithecus , with its eyes directed further forward. The neurocranium (braincase) was small and elevated relative to the face, unlike Palaeopropithecus . Postorbital constriction (narrowing of the skull behind the eye sockets) is pronounced. The skull also bore

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