Jump to content

Archaeolemur

From Wikipedia, the free encyclopedia

Archaeolemur
Temporal range:Holocene
Archaeolemur majoriskulls
Extinct(1047-1280)
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Family: †Archaeolemuridae
Genus: †Archaeolemur
Filhol,1895
Species
  • †Archaeolemur edwardsi(Filhol,1895)
  • †Archaeolemur majori
Filhol,1895
Synonyms[1]

Archaeolemuris an extinct genus ofsubfossil lemursknown from theHoloceneepoch ofMadagascar.[2]Archaeolemuris one of the most common and well-known of the extinctgiant lemursas hundreds of its bones have been discovered in fossil deposits across the island.[3][4]It was larger than any extant lemur, with a body mass of approximately 18.2–26.5 kg (40–58 lb), and is commonly reconstructed as the mostfrugivorousand terrestrial of the fossilMalagasyprimates.[5]Colloquially known as a "monkey lemur,"Archaeolemurhas often been compared with anthropoids, specifically thecercopithecines,due to various morphological convergences.[3][4]In fact, it was even misidentified as a monkey when remains were first discovered.[3]Following human arrival to Madagascar just over 2000 years ago, many of the island’smegafaunawent extinct, including the giant lemurs.Radiocarbon datingindicates thatArchaeolemursurvived on Madagascar until at least 1040-1290 AD, outliving most other subfossil lemurs.[2][6]

Taxonomy

[edit]

The genusArchaeolemurcomprises two known species:A. edwardsiandA. majori,with the former being larger and more robust than the latter.[3]The genus belongs to the family Archaeolemuridae, which, aside fromArchaeolemur,also includes the extinct speciesHadropithecus stenognathus.[4]Archaeolemuridae has historically been considered the sister group of the extinct family of subfossil lemurs,Paleopropithecidae(also known as the "sloth lemurs" ), and the extant family, Indriidae, mainly due to similarities in the teeth and skull.[7][8]This relationship has been contested by morphological analyses that instead grouped Archaeolemuridae more closely with Lemuridae.[3][7]One such analysis looked at ontogenetic data for Archaeolemur in order to extrapolate phylogenetic affinities and found the genus had more similarities withlemuridsthan withindriidsin terms of growth and development.[3]Despite such challenges, the sequencing of ancient DNA recovered fromA. edwardsi,A. majori,andHadropithecus stenognathusfossil specimens in a 2008 study lended important support to the phylogenetic placement of Archaeolemuridae as a sister group to living Indriidae, refuting Lemuridae asArchaeolemur’s closest relative.[7]The authors of that genetic study placed Archaeolemuridae, Paleopropithecidae, and Indriidae into the superfamily Indrioidea within the infraorder Lemuriformes, although the exact phylogenetic relationships between the three were still unclear.[7]A further genetic study in 2015 refined the phylogeny of Indrioidea, supporting a sister taxa relationship between Archaeolemuridae and the clade containing Paleopropithecidae and Indriidae.[8]

Functional morphology

[edit]
Life restoration ofArchaeolemur edwardsi

Archaeolemurhas a lower dental formula of 1-1-3-3. Therefore, the tooth comb, a key feature of strepsirrhines, consists of four teeth rather than the characteristic six teeth of most taxa.[4][7]This dental reduction is also observed in indriids and palaeopropithecids, suggesting this is a potential synapomorphy among these groups.[4][7]Microwear analysis of the lower incisors shows no evidence that the tooth comb ofArchaeolemurwas used for grooming.[3][9]Rather, the lower incisors are thought to have served a dietary function, such as the procurement and processing of food.[3][9]The upper incisors are large and spatulate, the premolars form a cutting edge, with the anterior lower premolar adopting a caniniform shape, and the molars are bilophodont and low-crowned.[4][9][10]This bilophodont molar morphology converges on that of cercopithecine molars.[4]These features have frequently been attributed to a frugivorous diet.[9]

The enamel ofArchaeolemurteeth is very thick and highlydecussated,which might have played a role in processing hard-objects.[3][10]Archaeolemuralso has a fusedmandibular symphysis,an adaptation for resisting chewing stress.[3]A biomechanical analysis of the jaw showed thatArchaeolemurwas well suited for breaking apart large food items[11]and dental microwear analysis ofA. edwardsiandA. majorimolars shows pitting that indicatesArchaeolemurprocessed harder foods, supporting a generalist diet.[10]Furthermore, the most similar microwear pattern among modern primates is found inCebus apella,a hard-object feeder.[12]Stable isotope analysis ofA. majoriindicatesArchaeolemurwas a consumer of C3 plants[13]and coprolites associated withArchaeolemurindicate an omnivorous diet that included fruit, seeds, and even small animals.[10]Overall, the evidence suggestsArchaeolemurhad a generalist diet that mainly consisted of fruit, seeds, and hard-objects.[5]

The postcranial skeletal morphology reveals important aspects ofArchaeolemur’s lifestyle. As the name "monkey lemur" suggests,Archaeolemurhas often been compared to theOld World monkeysdue to convergences in morphological and locomotory features, such as limb proportions.[4]While there are certainly similarities between the two, the convergences are sometimes overstated.[2][9]A comprehensive analysis of the hands and feet ofArchaeolemurshows that its limbs are relatively short for its body size, as are the hands and feet.[2]The pollex and hallux are reduced, along with the other digits, and were likely not prehensile; nevertheless, the ability to grasp when climbing was probably retained.[2][9]Archaeolemurhas broad apical tufts on the distal phalanges of both the hands and feet, which some have suggested might be related to grooming in the absence of a functioning tooth comb.[2][9]Unlike the Paleopropithecidae, or "sloth lemurs," who had highly curved proximal phalanges for suspensory behavior, the proximal phalanges ofArchaeolemurare straighter than those of all extinct Malagasy primates, although still more curved than those of baboons.[2][4][9]This morphological data, along with a previous study of the pelvis and scapula, support the conclusion thatArchaeolemur’s locomotory habits most likely consisted of both terrestrial and arboreal quadrupedalism.[2]It was probably neither cursorial, nor a leaper.[2]

Geographic range

[edit]

In order to reconstruct the geographic home range ofArchaeolemur,a study was conducted analyzing strontium isotope ratios from bone and tooth enamel of extinct and extant lemurs.[5]The authors found no significant difference in the median isotope variance when comparing values between extinct and living taxa. This suggests that despite larger body size, which typically predicts more mobility and more variable strontium isotope ratios, subfossil lemurs were likely not very active and did not have larger home ranges than living species.[5]Despite this relatively small home range for body size, Archaeolemur as a genus is believed to have been distributed across Madagascar and to have had a broad habitat tolerance.[2]

Extinction

[edit]

While it is difficult to pinpoint one specific factor that droveArchaeolemurto extinction, many authors agree that human activity upon arriving to Madagascar directly and indirectly impacted the island’s unique flora and fauna.[6][14]Human hunting likely played a primary role in the megafaunal extinctions, and would have had cascading effects on the structure of animal and plant communities. The modification of landscapes, includinghabitat fragmentationand habitat loss, would have added additional pressure on taxa like the giant lemurs, further driving them toward extinction.[6][14]Like modern species with low mobility and small home ranges, these characteristics might have madeArchaeolemurand its other fossil relatives vulnerable to extinction.[5]Large body size and frugivory are additional factors that might make organisms increasingly vulnerable when compared to smaller animals orfolivoresfacing habitat fragmentation or degradation.[5]Likewise, the terrestrial habit ofArchaeolemurmight have made it susceptible to human hunting.[14]GivenArchaeolemur’s larger body size compared to modern lemurs, its interpreted small home range, and its likely frugivorous diet, this genus may have been especially vulnerable to extinction when facing habitat change and human intervention on Madagascar. Nevertheless,Archaeolemurinhabited Madagascar until at least 1040-1290 AD, surviving longer than most other subfossil lemurs.[2][6]

Classification

[edit]

References

[edit]
  1. ^McKenna, MC; Bell, SK (1997).Classification of Mammals: Above the Species Level.Columbia University Press. p. 335.ISBN978-0-231-11013-6.
  2. ^abcdefghijkJungers, W.L., Lemelin, P., Godfrey, L.R., et al. (2005). The hands and feet of Archaeolemur: metrical affinities and their functional significance. Journal of Human Evolution, 49, 36-55. doi: 10.1016/j.jhevol.2005.03.001
  3. ^abcdefghijKing, S.J.; Godfrey, L.R.; Simons, E.L. (2001). "Adaptive and phylogenetic significance of ontogenetic sequences in Archaeolemur, subfossil lemur from Madagascar".Journal of Human Evolution.41(6): 545–576.Bibcode:2001JHumE..41..545K.doi:10.1006/jhev.2001.0509.PMID11782109.
  4. ^abcdefghiFleagle, J.G. (2013).Primate Adaptation & Evolution(3rd ed.). Academic Press.ISBN978-0123786326.
  5. ^abcdefCrowley, B.E.; Godfrey, L.R (2019)."Strontium Isotopes Support Small Home Ranges for Extinct Lemurs".Frontiers in Ecology and Evolution.7(1): 25–37.doi:10.1002/ajp.20817.PMID20205184.S2CID25469045.
  6. ^abcdBurney, D. A.; Burney, L. P.; Godfrey, L. R.; Jungers, W. L.; Goodman, S. M.; Wright, H. T.; Jull, A.J.T. (2004). "A chronology for late prehistoric Madagascar".Journal of Human Evolution.47(1–2): 25–63.Bibcode:2004JHumE..47...25B.doi:10.1016/j.jhevol.2004.05.005.PMID15288523.
  7. ^abcdefOrlando, L.; Calvignac, S.; Schnebelen, C.; Douady, C.J.; Godfrey, L.R.; Hanni, C. (2008)."DNA from extinct giant lemurs links archaeolemurids to extant indriids".BMC Evolutionary Biology.8(1): 121.Bibcode:2008BMCEE...8..121O.doi:10.1186/1471-2148-8-121.PMC2386821.PMID18442367.
  8. ^abKistler, L.; Ratan, A.; Godfrey, L.R.; et al. (2015). "Comparative and population mitogenomic analyses of Madagascar's extinct, giant 'subfossil' lemurs".Journal of Human Evolution.79:45–54.Bibcode:2015JHumE..79...45K.doi:10.1016/j.jhevol.2014.06.016.PMID25523037.
  9. ^abcdefghJungers, W.L.; Godfrey, L.R.; Simons, E.L.; Wunderlich, R.E.; Richmond, B.G.; Chatrath, P.S. (2002). "Ecomorphology and Behavior of Giant Extinct Lemurs from Madagascar". In Plavcan, J.M.; Kay, R.F.; Jungers, W.L.; van Schaik, C.P (eds.).Reconstructing Behavior in the Primate Fossil Record. Advances in Primatology.Boston, MA: Springer. pp. 371–411.doi:10.1007/978-1-4615-1343-8_10.ISBN978-1-4613-5507-6.
  10. ^abcdScott, J.R.; Godfrey, L.R.; Jungers, W.L.; Scott, R.S.; Simons, E.L.; Teaford, M.F.; Ungar, P.S.; Walker, A. (2009). "Dental microwear texture analysis of two families of subfossil lemurs from Madagascar".Journal of Human Evolution.56(4): 405–416.Bibcode:2009JHumE..56..405S.doi:10.1016/j.jhevol.2008.11.003.PMID19285707.
  11. ^Dumont, E.R.; Ryan, T.M.; Godfrey, L.R. (2011)."The Hadropithecus conundrum reconsidered, with implications for interpreting diet in fossil hominins".Proceedings of the Royal Society B.278(1725): 3654–3661.doi:10.1098/rspb.2011.0528.PMC3203504.PMID21525060.
  12. ^Godfrey, L. R.; Semprebon, G. M.; Jungers, W. L.; Sutherland, M. R.; Simons, E. L.; Solounias, N. (2004). "Dental use wear in extinct lemurs: evidence of diet and niche differentiation".Journal of Human Evolution.47(3): 145–169.Bibcode:2004JHumE..47..145G.doi:10.1016/j.jhevol.2004.06.003.PMID15337413.
  13. ^Crowley, B.E.; Godfrey, L.R.; Irwin, M.T. (2011)."A glance to the past: subfossils, stable isotopes, seed dispersal, and lemur species loss in Southern Madagascar".American Journal of Primatology.73(1): 25–37.doi:10.1002/ajp.20817.PMID20205184.S2CID25469045.
  14. ^abcGodfrey, L.R.; Irwin, M.T. (2007). "The Evolution of Extinction Risk: Past and Present Anthropogenic Impacts on the Primate Communities of Madagascar".Folia Primatologica.78(5–6): 405–419.doi:10.1159/000105152.PMID17855790.S2CID44848516.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Archaeolemur&oldid=1228415119"