Megaladapis
Megaladapis Temporal range: Pleistocene-Holocene
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Megaladapis edwardsi skeleton | |
Extinct (1280–1420 CE)
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Primates |
Suborder: | Strepsirrhini |
Superfamily: | Lemuroidea |
Family: | †Megaladapidae Forsyth Major, 1894[1] |
Genus: | †Megaladapis Forsyth Major, 1894[1] |
Species | |
Subgenus Peloriadapis
Subgenus Megaladapis
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Megaladapis, informally known as the koala lemur,[1][2] is an extinct genus of lemurs belonging to the family Megaladapidae, consisting of three species that once inhabited the island of Madagascar. The largest measured between 1.3 to 1.5 m (4 to 5 ft) in length.
Adaptations
Megaladapis was quite different from any living lemur. Its body was squat and built like that of the modern koala. Its long arms, fingers, feet, and toes were specialized for grasping trees, and its legs were splayed for vertical climbing. The hands and feet were curved and the ankles and wrists did not have the usual stability needed to travel on the ground that most other lemurids have.[3] Its pedal morphology suggests Megaladapis evolved to live in an arboreal environment. Its foot had a large hallux and lateral abductor musculature that helped it to grasp vertically on trees, features shared by other arboreal species.[4] Its head was unlike that of any other primate; most strikingly, its eyes were on the sides of its skull, instead of forward on the skull as in all other primates.
Its long
Its body weight reached 140 kg (310 lb).[8] Other estimates suggest 46.5–85.1 kg (103–188 lb) but its still much larger than any extanct lemur.[9] The shape of its skull was unique among all known primates, with a nasal region which showed similarities to those of rhinoceros, a feature that probably combined with an enlarged upper lip for grasping leaves.[citation needed] It had the largest body size of any lemur, with double the body mass of the next largest extinct lemur.[specify] An endocast of its skull showed that it had a brain capacity of about 250 cc, about 3 to 4 times the size of a domestic cat's,[10] which is small for its size when compared to other lemurs.[7] Compared to the size of the skull, the diameter of the orbits protrudes outwards and forwards in a tabular form, suggesting that Megaladapis was diurnal.[11] Based on when molar crown initiation occurred, Megaladapis's gestation period is thought to have been at least 198 days, but was likely longer.[7]
The island's topography was always changing, and like other lemurs, Megaladapis was specialized within its own niche. The general expectations of tree climbers such as Megaladapis is that with an increase in size, the body's forelimbs will also increase proportionally.[12]
Some exterior scratches and incisions were found on both its metatarsus and its mandibula. The cuts on the metatarsus are comparable to those found in caves and are thought to have been produced by humans, while those on the mandibula seem to have been produced by some instrument engineered for cutting – indications that the Megalapadis was at some point in direct contact with the anatomically-modern humans of its time.[11]
There are several well-preserved fragments of the upper and lower jaw. The upper molars of Lepilemur are very close in shape to those of Megaladapis. The main difference between the two is that the outer crown-surface of Lepilemur's molars forms a nearly straight line, almost parallel with the long axis of the skull, and the outer side is slightly concave inwards. The antero-internal cingulum is missing in the molars of Lepilemur.[10]
Details about the anterior parts of the dentition, the canines and incisors, are difficult to determine. The bulle osseve[clarification needed] are broken away. The foremost facial portion and base of the skull is also wanting. The total length of the skull of M. madagascariensis has been calculated to be about 250 mm (9.8 in), about from three to four times that of a domestic cat. Based on the wear on the teeth, the obliteration of most of the sutures of the very thick bones, and the strongly developed crests, it is believed to have been an elderly individual.[13]
Cultural references
It is often believed that
Extinction
When humans arrived on Madagascar 2,300 years ago, in addition to the species alive today, there were at least 17 species of now-extinct "giant" lemur, including Megaladapis. The landscape in which giant lemurs were found were largely forested areas with dense vegetation. Almost directly after human arrival, there was a rapid decline in the spores of Sporormiella which indicates a decrease in megafaunal biomass. Charcoal microparticles being found in surveys of various areas in Madagascar give evidence to the fact that human habitat modification only occurred after this decline in megafaunal biomass. Charcoal deposits provide evidence to the fact that humans used fire to clear large pieces of land very rapidly. The habitats that Megaladapis once lived in were very well adapted to be turned into grasslands, which provided little to no cover from outside forces for these creatures. Thus, the scientific conclusion arrived upon is one that hypothesizes that "giant" lemur populations, like the Megaladapis, were on the decline due to habitat fragmentation, and human activities (for example, clearing of land through "slash-and-burn" techniques) were the final push to extinction for these lemurs between 500 and 600 years ago.[15]
Megaladapis were slow-moving, bulky creatures that were diurnal, or active during the day. Lemurs in general also had small group sizes and were highly seasonal breeders (they breed for about one to two weeks a year).[17] These features already put them at an evolutionary disadvantage; Megaladapis (along with the other species of giant lemur) were more susceptible to predators (humans more specifically), forest fires, and habitat destruction due to these traits.[18] The low breeding rates also made recovery from devastating loss of life among the species very difficult to recover from, as evidenced by the eventual extinction of Megaladapis.[17]
Gallery
References
- ^ ISBN 978-1-881173-88-5.
- ISBN 978-0-8018-6251-9.
- PMID 17576932.
- PMID 8859959.
- PMID 25619123.)
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: CS1 maint: multiple names: authors list (link - PMID 34162703.
- ^ ISBN 978-1-4020-5844-8.
- ISBN 9780080492131.
- ^ Crowley, B.E., & Godfrey, L.R. (2019). "Strontium Isotopes Support Small Home Ranges for Extinct Lemurs". Frontiers in Ecology and Evolution, 7, 490. doi: 10.1002/ajp.20817
- ^ JSTOR 91769.
- ^ . Retrieved October 26, 2015.
- PMID 6776705.
- ^ JSTOR 91919.
- ISBN 978-0-226-30306-2.
- PMID 20226497.
- S2CID 84382916.
- ^ a b Scott, Rob. "The Lost Lemurs: Extinction in Madagascar." Rutgers University. Hickman Hall, New Brunswick, NJ. n.d. Lecture.
- PMID 17754597.