Babakotia
Encyclopedia
Babakotia is a medium-sized, extinct genus
of 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 trait
s that show intermediate stages between the living indriid
s and the large sloth lemurs, it has helped determine the relationship between both groups and the closely related and extinct monkey lemur
s.
Babakotia radofilai and all other sloth lemurs share many traits with living sloth
s, demonstrating convergent evolution
. It had long forearms, curved digits, and highly mobile hip and ankle joints. Its skull was more heavily built than that of indriids, but not as much as in the larger sloth lemurs. Its dentition
is similar to that of all other indriids and sloth lemurs. It lived in the northern part of Madagascar and shared its range with at least two other sloth lemur species, Palaeopropithecus ingens and Mesopropithecus dolichobrachion. Babakotia radofilai was primarily a leaf-eater (folivore
), though it also ate fruit and hard seeds. It is known only from subfossil
remains and may have died out shortly after the arrival of humans on the island, but not enough radiocarbon dating
has been done with this species to know for certain.
common name for the Indri
, babakoto, a close relative of Babakotia. The species name
, radofilai, was chosen in honor of French mathematician and expatriate
Jean Radofilao, an avid spelunker
who mapped the caves where remains of Babakotia radofilai were first found.
Babakotia and belongs to the family
Palaeopropithecidae, which includes three other genera of sloth lemurs: Palaeopropithecus, Archaeoindris
, and Mesopropithecus
. This family in turn belongs to the infraorder
Lemuriformes, which includes all the Malagasy lemurs.
The first subfossil remains of Babakotia radofilai were discovered as part of a series of expeditions launched in the early 1980s by biological anthropologist
Elwyn Simons. They were unearthed in 1988 at a cave known as Antsiroandoha in the Ankarana Massif
, northern Madagascar. A nearly complete skeleton and skull were found, in addition to the remains of roughly a dozen other individuals. Identified immediately as a sloth lemur (palaeopropithecid) upon its discovery, Babakotia along with Mesopropithecus helped to settle a debate about the relationship between the sloth lemurs, the monkey lemur
s (family Archaeolemuridae) and the living indriid
s. The monkey lemurs had skulls that more closely resembled the indriids, but their teeth were very specialized and unlike those of the indriids. The larger sloth lemurs, on the other hand, retained a dentition
similar to living indriids, yet differed by having more robust and specialized skulls. Babakotia and Mesopropithecus not only shared the indriid dentition, but also the indriid-like skulls, providing evidence that sloth lemurs were most closely related to living indriids, with monkey lemurs as a sister group
to both. Furthermore, the discovery of Babakotia helped to demonstrate that the ancestral indriids were not "ricochetal leapers" (bouncing rapidly from tree to tree) like living indriids, but vertical climbers and hanging feeders, and possibly occasional leapers.
between the large sloth lemurs and the small sloth lemurs. This includes its highly mobile hip and ankle joints, as well as other specializations in the vertebral column, pelvis, and limbs. Its forelimb
s were 20% longer than its hind limb
s, giving it a higher intermembral index (~119) than Mesopropithecus (~97 to 113), suggesting that it was convergently
similar to arboreal
sloth
s. It had a reduced tarsus
and curved, elongated digits, adapted for grasping and suggesting suspensory behavior. Its hind feet were reduced, making it well-adapted for climbing and hanging (like in other palaeopropithecids), but not leaping (like in indriids). Wrist bones found in 1999 further demonstrated that this species was a vertical climber. Additionally, analysis of its semicircular canals, lumbar vertebrae
and its spinous processes indicate slow movement and climbing (antipronograde) adaptations, but not necessarily sloth-like hanging, vertical clinging, or leaping. Therefore, it was likely a slow climber like a loris
and also exhibited some suspensory behavior like a sloth.
All sloth lemurs have relatively robust skulls compared to the indriids, yet despite shared cranial features with the larger sloth lemurs, its skull still resembles that of an Indri. The cranial traits shared with the other sloth lemurs include relatively small orbit
s, robust zygomatic arch
es, and a mostly rectangular hard palate
. The small orbits taken into consideration with the relative size of the optic canal suggests that Babakotia had low visual acuity
, which is typical for lemurs. The skull length averages 144 mm (5.7 in).
The dental formula
of Babakotia radofilai was the same as the other sloth lemurs and indriids: either or . It is unclear whether one of the teeth in the permanent dentition
is an incisor
or canine
, resulting in these two conflicting dental formulae. Regardless, the lack of either a lower canine or incisor results in a four-tooth toothcomb
instead of the more typical six-tooth strepsirrhine toothcomb. Babakotia radofilai differed slightly from indriids in having somewhat elongated premolar
s. Its cheek teeth had broad shearing crests and crenulated enamel
.
, or some other unknown factor. It was sympatric (occurred together) with Palaeopropithecus maximus and Mesopropithecus dolichobrachion.
Based on its size, the morphology of its molars, and microwear analysis on its teeth, Babakotia radofilai was likely a folivore
, while supplementing its diet with fruit and hard seeds
. In all sloth lemurs, including Babakotia radofilai, the permanent teeth erupted early, a trait seen in indriids that improves survivability of juveniles during the first dry season following weaning
.
epoch
and is thought to have disappeared shortly after the arrival of humans to the island, possibly within the last 1000 years. However, the only radiocarbon date
that has been reported for it dates back to about 3100–2800 BCE.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of lemur
Lemur
Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...
, or strepsirrhine primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
, from Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
that contains a single species, Babakotia radofilai. Together with Palaeopropithecus, Archaeoindris
Archaeoindris
Archaeoindris fontoynonti is an extinct species of Malagasy lemur that was the largest primate to evolve on Madagascar. It weighed about and measured around 1.5m in height, more than a silverback gorilla. Archaeoindris is one of eight known members of the Palaeopropithecinae subfamily...
, and Mesopropithecus
Mesopropithecus
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...
, it forms the family Palaeopropithecidae, commonly known as the sloth lemurs. The name Babakotia comes from the Malagasy
Malagasy language
Malagasy is the national language of Madagascar, a member of the Austronesian family of languages. Most people in Madagascar speak it as a first language as do some people of Malagasy descent elsewhere.-History:...
name for the Indri
Indri
The indri , also called the babakoto, is one of the largest living lemurs. It is a diurnal tree-dweller related to the sifakas and, like all lemuroids, it is native to Madagascar.- Etymology :...
, babakoto, to which it and all other sloth lemurs are closely related. Due to its mix of morphological trait
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
s that show intermediate stages between the living indriid
Indriidae
The Indriidae are a family of strepsirrhine primates. They are medium to large sized lemurs with only four teeth in the toothcomb instead of the usual six...
s and the large sloth lemurs, it has helped determine the relationship between both groups and the closely related and extinct monkey lemur
Monkey lemur
The Monkey lemurs or Baboon lemurs are an extinct type of lemurs that includes one family, Archaeolemuridae, two genera and three species. Despite their common names, members of Archaeolemuridae were not as closely related to monkeys as they were to other lemurs....
s.
Babakotia radofilai and all other sloth lemurs share many traits with living sloth
Sloth
Sloths are the six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae , part of the order Pilosa and therefore related to armadillos and anteaters, which sport a similar set of specialized claws.They are arboreal residents of the jungles of Central and South...
s, demonstrating convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
. It had long forearms, curved digits, and highly mobile hip and ankle joints. Its skull was more heavily built than that of indriids, but not as much as in the larger sloth lemurs. Its dentition
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
is similar to that of all other indriids and sloth lemurs. It lived in the northern part of Madagascar and shared its range with at least two other sloth lemur species, Palaeopropithecus ingens and Mesopropithecus dolichobrachion. Babakotia radofilai was primarily a leaf-eater (folivore
Folivore
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds. For this reason folivorous animals tend to have long digestive tracts and slow metabolisms....
), though it also ate fruit and hard seeds. It is known only from subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
remains and may have died out shortly after the arrival of humans on the island, but not enough radiocarbon dating
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...
has been done with this species to know for certain.
Etymology
The name of the genus Babakotia derives from the MalagasyMalagasy language
Malagasy is the national language of Madagascar, a member of the Austronesian family of languages. Most people in Madagascar speak it as a first language as do some people of Malagasy descent elsewhere.-History:...
common name for the Indri
Indri
The indri , also called the babakoto, is one of the largest living lemurs. It is a diurnal tree-dweller related to the sifakas and, like all lemuroids, it is native to Madagascar.- Etymology :...
, babakoto, a close relative of Babakotia. The species name
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, radofilai, was chosen in honor of French mathematician and expatriate
Expatriate
An expatriate is a person temporarily or permanently residing in a country and culture other than that of the person's upbringing...
Jean Radofilao, an avid spelunker
Caving
Caving—also occasionally known as spelunking in the United States and potholing in the United Kingdom—is the recreational pastime of exploring wild cave systems...
who mapped the caves where remains of Babakotia radofilai were first found.
Classification and phylogeny
Babakotia radofilai is the sole member of the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Babakotia and belongs to the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Palaeopropithecidae, which includes three other genera of sloth lemurs: Palaeopropithecus, Archaeoindris
Archaeoindris
Archaeoindris fontoynonti is an extinct species of Malagasy lemur that was the largest primate to evolve on Madagascar. It weighed about and measured around 1.5m in height, more than a silverback gorilla. Archaeoindris is one of eight known members of the Palaeopropithecinae subfamily...
, and Mesopropithecus
Mesopropithecus
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...
. This family in turn belongs to the infraorder
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Lemuriformes, which includes all the Malagasy lemurs.
The first subfossil remains of Babakotia radofilai were discovered as part of a series of expeditions launched in the early 1980s by biological anthropologist
Biological anthropology
Biological anthropology is that branch of anthropology that studies the physical development of the human species. It plays an important part in paleoanthropology and in forensic anthropology...
Elwyn Simons. They were unearthed in 1988 at a cave known as Antsiroandoha in the Ankarana Massif
Ankarana Reserve
Ankarana Reserve is a small, partially vegetated plateau in northern Madagascar composed of 150-million-year-old middle Jurassic limestone. With an average annual rainfall of about , the underlying rocks are susceptible to erosion, thereby producing caves and underground rivers—a karst topography...
, northern Madagascar. A nearly complete skeleton and skull were found, in addition to the remains of roughly a dozen other individuals. Identified immediately as a sloth lemur (palaeopropithecid) upon its discovery, Babakotia along with Mesopropithecus helped to settle a debate about the relationship between the sloth lemurs, the monkey lemur
Monkey lemur
The Monkey lemurs or Baboon lemurs are an extinct type of lemurs that includes one family, Archaeolemuridae, two genera and three species. Despite their common names, members of Archaeolemuridae were not as closely related to monkeys as they were to other lemurs....
s (family Archaeolemuridae) and the living indriid
Indriidae
The Indriidae are a family of strepsirrhine primates. They are medium to large sized lemurs with only four teeth in the toothcomb instead of the usual six...
s. The monkey lemurs had skulls that more closely resembled the indriids, but their teeth were very specialized and unlike those of the indriids. The larger sloth lemurs, on the other hand, retained a dentition
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
similar to living indriids, yet differed by having more robust and specialized skulls. Babakotia and Mesopropithecus not only shared the indriid dentition, but also the indriid-like skulls, providing evidence that sloth lemurs were most closely related to living indriids, with monkey lemurs as a sister group
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
to both. Furthermore, the discovery of Babakotia helped to demonstrate that the ancestral indriids were not "ricochetal leapers" (bouncing rapidly from tree to tree) like living indriids, but vertical climbers and hanging feeders, and possibly occasional leapers.
Anatomy and physiology
Weighing between 16 and 20 kg (35.3 and 44.1 lb), Babakotia radofilai was a medium-sized lemur and noticeably smaller than the large sloth lemurs (Archaeoindris and Palaeopropithecus), but larger than the small sloth lemurs (Mesopropithecus). In many ways, it had an intermediate level of adaptations for suspensory behaviorSuspensory behavior
Suspensory Behavior, exhibited by primates, is a form of arboreal locomotion or a feeding behavior which involves hanging or suspension of the body below or among the branches, rather than moving or sitting on top of the branches...
between the large sloth lemurs and the small sloth lemurs. This includes its highly mobile hip and ankle joints, as well as other specializations in the vertebral column, pelvis, and limbs. Its forelimb
Forelimb
A forelimb is an anterior limb on an animal's body. When referring to quadrupeds , the term foreleg is often instead used....
s were 20% longer than its hind limb
Hind limb
A hind limb is a posterior limb on an animal. When referring to quadrupeds, the term hind leg is often instead used....
s, giving it a higher intermembral index (~119) than Mesopropithecus (~97 to 113), suggesting that it was convergently
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
similar to arboreal
Arboreal locomotion
Arboreal locomotion is the locomotion of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals...
sloth
Sloth
Sloths are the six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae , part of the order Pilosa and therefore related to armadillos and anteaters, which sport a similar set of specialized claws.They are arboreal residents of the jungles of Central and South...
s. It had a reduced tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
and curved, elongated digits, adapted for grasping and suggesting suspensory behavior. Its hind feet were reduced, making it well-adapted for climbing and hanging (like in other palaeopropithecids), but not leaping (like in indriids). Wrist bones found in 1999 further demonstrated that this species was a vertical climber. Additionally, analysis of its semicircular canals, lumbar vertebrae
Lumbar vertebrae
The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...
and its spinous processes indicate slow movement and climbing (antipronograde) adaptations, but not necessarily sloth-like hanging, vertical clinging, or leaping. Therefore, it was likely a slow climber like a loris
Loris
Loris is the common name for the strepsirrhine primates of the subfamily Lorisinae in family Lorisidae. Loris is one genus in this subfamily and includes the slender lorises, while Nycticebus is the genus for the slow lorises....
and also exhibited some suspensory behavior like a sloth.
All sloth lemurs have relatively robust skulls compared to the indriids, yet despite shared cranial features with the larger sloth lemurs, its skull still resembles that of an Indri. The cranial traits shared with the other sloth lemurs include relatively small orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
s, robust zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es, and a mostly rectangular hard palate
Hard palate
The hard palate is a thin horizontal bony plate of the skull, located in the roof of the mouth. It spans the arch formed by the upper teeth.It is formed by the palatine process of the maxilla and horizontal plate of palatine bone....
. The small orbits taken into consideration with the relative size of the optic canal suggests that Babakotia had low visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
, which is typical for lemurs. The skull length averages 144 mm (5.7 in).
The dental formula
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
of Babakotia radofilai was the same as the other sloth lemurs and indriids: either or . It is unclear whether one of the teeth in the permanent dentition
Permanent teeth
Permanent teeth are the second set of teeth formed in humans. There are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.The first...
is an incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
or canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
, resulting in these two conflicting dental formulae. Regardless, the lack of either a lower canine or incisor results in a four-tooth toothcomb
Toothcomb
A toothcomb is an anatomical structure found in strepsirrhine primates, which includes lemurs, lorises and galagos. A toothcomb consists of long, flat forward-angled teeth, and includes the lower incisors and the canine teeth...
instead of the more typical six-tooth strepsirrhine toothcomb. Babakotia radofilai differed slightly from indriids in having somewhat elongated premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
s. Its cheek teeth had broad shearing crests and crenulated enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
.
Distribution and ecology
Like all other lemurs, Babakotia radofilai was endemic to Madagascar. Its remains have only been found in limestone caves at the Ankarana Massif and Anjohibe, indicating a range across the extreme north and northwest of the island. The restricted range of this arboreal primate, particularly during a time when much of the island was blanketed in forest, might have been due to habitat specificity, competitive exclusionCompetitive exclusion principle
In ecology, the competitive exclusion principle, sometimes referred to as Gause's law of competitive exclusion or just Gause's law, is a proposition which states that two species competing for the same resources cannot coexist if other ecological factors are constant...
, or some other unknown factor. It was sympatric (occurred together) with Palaeopropithecus maximus and Mesopropithecus dolichobrachion.
Based on its size, the morphology of its molars, and microwear analysis on its teeth, Babakotia radofilai was likely a folivore
Folivore
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds. For this reason folivorous animals tend to have long digestive tracts and slow metabolisms....
, while supplementing its diet with fruit and hard seeds
Seed predation
Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores feed on the seeds of plants as a main or exclusive food source, in many cases leaving the seeds damaged and not viable...
. In all sloth lemurs, including Babakotia radofilai, the permanent teeth erupted early, a trait seen in indriids that improves survivability of juveniles during the first dry season following weaning
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...
.
Extinction
Because it died out relatively recently and is only known from subfossil remains, it is considered to be a modern form of Malagasy lemur. Babakotia radofilai lived during the HoloceneHolocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
and is thought to have disappeared shortly after the arrival of humans to the island, possibly within the last 1000 years. However, the only radiocarbon date
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...
that has been reported for it dates back to about 3100–2800 BCE.