Archaeolemur

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Archaeolemur
Temporal range: Holocene
Archaeolemur majori skulls.JPG
Archaeolemur majori skulls
Extinct  (1047-1280)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Family:† Archaeolemuridae
Genus:† Archaeolemur
Filhol, 1895
Species
  • †Archaeolemur edwardsi
  • †Archaeolemur majori
Synonyms [1]
  • BradylemurGrandidier, 1899
  • GlobilemurForsyth Major, 1898
  • NesopithecusForsyth Major, 1896

Archaeolemur is an extinct genus of subfossil lemurs known from the Holocene epoch of Madagascar. [2] Archaeolemur is one of the most common and well-known of the extinct giant lemurs as 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 most frugivorous and terrestrial of the fossil Malagasy primates. [5] Colloquially known as a "monkey lemur," Archaeolemur has often been compared with anthropoids, specifically the cercopithecines, 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’s megafauna went extinct, including the giant lemurs. Radiocarbon dating indicates that Archaeolemur survived on Madagascar until at least 1040-1290 AD, outliving most other subfossil lemurs. [2] [6]

Contents

Taxonomy

The genus Archaeolemur comprises two known species: A. edwardsi and A. majori, with the former being larger and more robust than the latter. [3] The genus belongs to the family Archaeolemuridae, which, aside from Archaeolemur, also includes the extinct species Hadropithecus 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 with lemurids than with indriids in terms of growth and development. [3] Despite such challenges, the sequencing of ancient DNA recovered from A. edwardsi, A. majori, and Hadropithecus stenognathus fossil specimens in a 2008 study lended important support to the phylogenetic placement of Archaeolemuridae as a sister group to living Indriidae, refuting Lemuridae as Archaeolemur’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

Life restoration of Archaeolemur edwardsi Archaeolemur edwardsi.jpg
Life restoration of Archaeolemur edwardsi

Archaeolemur has 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 of Archaeolemur was 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 of Archaeolemur teeth is very thick and highly decussated, which might have played a role in processing hard-objects. [3] [10] Archaeolemur also has a fused mandibular symphysis, an adaptation for resisting chewing stress. [3] A biomechanical analysis of the jaw showed that Archaeolemur was well suited for breaking apart large food items [11] and dental microwear analysis of A. edwardsi and A. majori molars shows pitting that indicates Archaeolemur processed harder foods, supporting a generalist diet. [10] Furthermore, the most similar microwear pattern among modern primates is found in Cebus apella, a hard-object feeder. [12] Stable isotope analysis of A. majori indicates Archaeolemur was a consumer of C3 plants [13] and coprolites associated with Archaeolemur indicate an omnivorous diet that included fruit, seeds, and even small animals. [10] Overall, the evidence suggests Archaeolemur had a generalist diet that mainly consisted of fruit, seeds, and hard-objects. [5]

The postcranial skeletal morphology reveals important aspects of Archaeolemur’s lifestyle. As the name "monkey lemur" suggests, Archaeolemur has often been compared to the Old World monkeys due 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 of Archaeolemur shows 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] Archaeolemur has 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 of Archaeolemur are 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 that Archaeolemur’s locomotory habits most likely consisted of both terrestrial and arboreal quadrupedalism. [2] It was probably neither cursorial, nor a leaper. [2]

Geographic range

In order to reconstruct the geographic home range of Archaeolemur, 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

While it is difficult to pinpoint one specific factor that drove Archaeolemur to 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, including habitat fragmentation and 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 made Archaeolemur and 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 or folivores facing habitat fragmentation or degradation. [5] Likewise, the terrestrial habit of Archaeolemur might have made it susceptible to human hunting. [14] Given Archaeolemur’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, Archaeolemur inhabited Madagascar until at least 1040-1290 AD, surviving longer than most other subfossil lemurs. [2] [6]

Classification

Related Research Articles

<span class="mw-page-title-main">Lemuridae</span> Family of lemurs

Lemuridae is a family of strepsirrhine primates native to Madagascar and the Comoros. They are represented by the Lemuriformes in Madagascar with one of the highest concentration of the lemurs. One of five families commonly known as lemurs. These animals were once thought to be the evolutionary predecessors of monkeys and apes, but this is no longer considered correct. They are formally referred to as lemurids.

<span class="mw-page-title-main">Strepsirrhini</span> Suborder of primates

Strepsirrhini or Strepsirhini is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Collectively they are referred to as strepsirrhines. Also belonging to the suborder are the extinct adapiform primates which thrived during the Eocene in Europe, North America, and Asia, but disappeared from most of the Northern Hemisphere as the climate cooled. Adapiforms are sometimes referred to as being "lemur-like", although the diversity of both lemurs and adapiforms does not support this comparison.

<span class="mw-page-title-main">Lemur</span> Clade of primates endemic to the island of Madagascar

Lemurs are wet-nosed primates of the superfamily Lemuroidea, divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to 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.

<i>Megaladapis</i> Extinct genus of lemurs

Megaladapis, informally known as the koala lemur, was a genus belonging to the family Megaladapidae, consisting of three extinct species of lemurs that once inhabited the island of Madagascar. The largest measured between 1.3 to 1.5 m in length.

<i>Archaeoindris</i> Extinct giant lemur

Archaeoindris fontoynontii 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, 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.

<i>Palaeopropithecus</i> Extinct genus of lemurs

Palaeopropithecus is a recently extinct genus of large sloth lemurs from Madagascar related to living lemur species found there today. Three species are known, Palaeopropithecus ingens, P. maximus, and P. kelyus. Radiocarbon dates indicate that they may have survived until around 1300–1620 CE. Malagasy legends of the tretretretre or tratratratra are thought to refer to P. ingens.

<span class="mw-page-title-main">Monkey lemur</span> Extinct family of lemurs

The monkey lemurs or baboon lemurs (Archaeolemuridae) are a recently extinct family of lemurs known from skeletal remains from sites on Madagascar dated to 1000 to 3000 years ago.

<span class="mw-page-title-main">Sloth lemur</span> Extinct family of lemurs

The sloth lemurs (Palaeopropithecidae) comprise an extinct family of lemurs that includes four genera. The common name can be misleading, as members of Palaeopropithecidae were not closely related to sloths. This clade has been dubbed the ‘‘sloth lemurs’’ because of remarkable postcranial convergences with South American sloths. Despite postcranial similarities, the hands and feet show significant differences. Sloths possess long, curved claws, while sloth lemurs have short, flat nails on their distal phalanges like most primates.

<i>Pachylemur</i> Extinct genus of lemurs

Pachylemur is an extinct, giant lemur most closely related to the ruffed lemurs of genus Varecia. Two species are known, Pachylemur insignis and Pachylemur jullyi, although there is some doubt as to whether or not they may actually be the same species. Pachylemur is sometimes referred to as the giant ruffed lemur, because although it and the living ruffed lemurs had similar teeth and skeletons, Pachylemur was more robust and as much as three to four times larger. DNA studies have confirmed a sister group relationship between these two types of lemur. Like living ruffed lemurs, Pachylemur specialized in eating fruit, and was therefore an important seed disperser, possibly for tree species with seeds too large for even ruffed lemurs to swallow. In the spiny thickets of southwestern Madagascar, they were also likely to have dispersed seeds evolved to attach to fur and be carried away. Unlike ruffed lemurs, the fore- and hindlimbs of Pachylemur were nearly the same length, and therefore it was likely to be a slow, deliberate climber. However, both used hindlimb suspension to reach fruit on small branches below them.

<i>Hadropithecus</i> Extinct genus of lemurs

Hadropithecus is a medium-sized, extinct genus of lemur, or strepsirrhine primate, from Madagascar that includes a single species, Hadropithecus stenognathus. Due to its rarity and lack of sufficient skeletal remains, it is one of the least understood of the extinct lemurs. Both it and Archaeolemur are collectively known as "monkey lemurs" or "baboon lemurs" due to body plans and dentition that suggest a terrestrial lifestyle and a diet similar to that of modern baboons. Hadropithecus had extended molars and a short, powerful jaw, suggesting that it was both a grazer and a seed predator.

<i>Babakotia</i> Extinct genus of lemurs

Babakotia is an extinct genus of medium-sized lemur, or strepsirrhine primate, from Madagascar that contains a single species, Babakotia radofilai. Together with Palaeopropithecus, Archaeoindris, and Mesopropithecus, it forms the family Palaeopropithecidae, commonly known as the sloth lemurs. The name Babakotia comes from the Malagasy name for the indri, babakoto, to which it and all other sloth lemurs are closely related. Due to its mix of morphological traits that show intermediate stages between the slow-moving smaller sloth lemurs and the suspensory large sloth lemurs, it has helped determine the relationship between both groups and the closely related and extinct monkey lemurs.

<i>Mesopropithecus</i> Extinct genus of small to medium-sized lemur from Madagascar

Mesopropithecus is an extinct genus of small to medium-sized lemur, or strepsirrhine primate, from Madagascar that includes three species, M. dolichobrachion, M. globiceps, and M. pithecoides. Together with Palaeopropithecus, Archaeoindris, and Babakotia, it is part of the sloth lemur family (Palaeopropithecidae). Once thought to be an indriid because its skull is similar to that of living sifakas, a recently discovered postcranial skeleton shows Mesopropithecus had longer forelimbs than hindlimbs—a distinctive trait shared by sloth lemurs but not by indriids. However, as it had the shortest forelimbs of all sloth lemurs, it is thought that Mesopropithecus was more quadrupedal and did not use suspension as much as the other sloth lemurs.

<span class="mw-page-title-main">Evolution of lemurs</span> History of primate evolution on Madagascar

Lemurs, primates belonging to the suborder Strepsirrhini which branched off from other primates less than 63 million years ago, evolved on the island of Madagascar, for at least 40 million years. They share some traits with the most basal primates, and thus are often confused as being ancestral to modern monkeys, apes, and humans. Instead, they merely resemble ancestral primates.

<span class="mw-page-title-main">Subfossil lemur</span> Lemurs from Madagascar that are represented by recent (subfossil) remains

Subfossil lemurs are lemurs from Madagascar that are represented by recent (subfossil) remains dating from nearly 26,000 years ago to approximately 560 years ago. They include both extant and extinct species, although the term more frequently refers to the extinct giant lemurs. The diversity of subfossil lemur communities was greater than that of present-day lemur communities, ranging from as high as 20 or more species per location, compared with 10 to 12 species today. Extinct species are estimated to have ranged in size from slightly over 10 kg (22 lb) to roughly 160 kg (350 lb). Even the subfossil remains of living species are larger and more robust than the skeletal remains of modern specimens. The subfossil sites found around most of the island demonstrate that most giant lemurs had wide distributions and that ranges of living species have contracted significantly since the arrival of humans.

<span class="mw-page-title-main">Taxonomy of lemurs</span> Science of describing species and defining the evolutionary relationships between taxa of lemurs

Lemurs were first classified in 1758 by Carl Linnaeus, and the taxonomy remains controversial today, with approximately 70 to 100 species and subspecies recognized, depending on how the term "species" is defined. Having undergone their own independent evolution on Madagascar, lemurs have diversified to fill many ecological niches normally filled by other types of mammals. They include the smallest primates in the world, and once included some of the largest. Since the arrival of humans approximately 2,000 years ago, lemurs have become restricted to 10% of the island, or approximately 60,000 square kilometers (23,000 sq mi), and many face extinction. Concerns over lemur conservation have affected lemur taxonomy, since distinct species receive increased conservation attention compared to subspecies.

Charles Lamberton was a French paleontologist who lived and studied on the island of Madagascar between 1911 and 1948 and specialized in the recently extinct subfossil lemurs. He made significant contributions towards fixing misattributions of skeletal remains and poor interpretations of subfossil lemur behavior. His paleontological expeditions during the 1930s led to the discovery of a new species of Mesopropithecus, a type of sloth lemur. Three species—one mammal and two reptiles—were named after him, although one is now considered a taxonomic synonym.

<span class="mw-page-title-main">Berthe Rakotosamimanana</span> Malagasy primatologist and paleontologist

Berthe Rakotosamimanana was a primatologist and palaeontologist from Madagascar.

<span class="mw-page-title-main">Andrahomana Cave</span> Complex of sinkholes in south eastern Madagascar

The Andrahomana Cave is a complex of sinkholes in Andranobory in south eastern Madagascar.

Ampasambazimba is a mountain peak and subfossil site in Madagascar, near Analavory, (Itasy) most known for being the site of the remains of the extinct giant sloth lemur Archaeoindris.

References

  1. ↑ McKenna, MC; Bell, SK (1997). Classification of Mammals: Above the Species Level. Columbia University Press. p. 335. ISBN   978-0-231-11013-6.
  2. 1 2 3 4 5 6 7 8 9 10 11 Jungers, 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. 1 2 3 4 5 6 7 8 9 10 King, 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. doi:10.1006/jhev.2001.0509. PMID   11782109.
  4. 1 2 3 4 5 6 7 8 9 Fleagle, J.G. (2013). Primate Adaptation & Evolution (3rd ed.). Academic Press. ISBN   978-0123786326.
  5. 1 2 3 4 5 6 Crowley, 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 . PMID   20205184. S2CID   25469045.
  6. 1 2 3 4 Burney, 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. doi:10.1016/j.jhevol.2004.05.005. PMID   15288523.
  7. 1 2 3 4 5 6 Orlando, 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: 121. doi:10.1186/1471-2148-8-121. PMC   2386821 . PMID   18442367.
  8. 1 2 Kistler, 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. doi:10.1016/j.jhevol.2014.06.016. PMID   25523037.
  9. 1 2 3 4 5 6 7 8 Jungers, 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. ISBN   978-1-4613-5507-6.
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  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. PMC   3203504 . PMID   21525060.
  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. doi:10.1016/j.jhevol.2004.06.003. PMID   15337413.
  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 . PMID   20205184. S2CID   25469045.
  14. 1 2 3 Godfrey, 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. PMID   17855790. S2CID   44848516.
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