''Ambondro mahabo'' is a
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
from the
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
(
Bathonian
In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age.
Strat ...
)
Isalo III Formation
The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.Weishampel et al., 2004, pp.542-543 The use of the term "Isalo III" is somewhat controversial as the two prior u ...
(about 167 million years ago) of
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. The only described species of the genus ''Ambondro'', it is known from a fragmentary
lower jaw
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
with three teeth, interpreted as the last
premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
and the first two
molars
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
. The premolar consists of a central
cusp
A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth.
Cusp or CUSP may also refer to:
Mathematics
* Cusp (singularity), a singular point of a curve
* Cusp catastrophe, a branch of bifurca ...
with one or two smaller cusps and a
cingulum (shelf) on the inner, or lingual, side of the tooth. The molars also have such a lingual cingulum. They consist of two groups of cusps: a
trigonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...
of three cusps at the front and a
talonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
with a main cusp, a smaller cusp, and a crest at the back. Features of the talonid suggest that ''Ambondro'' had
tribosphenic molar
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
s, the basic arrangement of molar features also present in
marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...
and
placental
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsup ...
mammals. It is the oldest known mammal with putatively tribosphenic teeth; at the time of its discovery it antedated the second oldest example by about 25 million years.
Upon its description in 1999, ''Ambondro'' was interpreted as a primitive relative of
Tribosphenida
Tribosphenida is a group (infralegion) of mammals that includes the ancestor of ''Hypomylos'', Aegialodontia and Theria (the last common ancestor of marsupials and placentals plus all of its descendants). Its current definition is more or less sy ...
(marsupials, placentals, and their extinct tribosphenic-toothed relatives). In 2001, however, an alternative suggestion was published that united it with the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
Australian ''
Ausktribosphenos
''Ausktribosphenos'' is an extinct genus of mammals from Early Cretaceous of Australia. The only recorded species, ''Ausktribosphenos nyktos'', was found on Flat Rocks, Victoria
Victoria most commonly refers to:
* Victoria (Australia), a st ...
'' and the
monotreme
Monotremes () are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals (Eutheria), and marsupials (Metatheria). Monotremes are typified by structural differences in their brain ...
s (the
echidna
Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...
s, the
platypus
The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal Endemic (ecology), endemic to Eastern states of Australia, eastern Australia, including Tasmania. The platypu ...
, and their extinct relatives) into the clade
Australosphenida
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. They are thought to have acquired their tribosphenic molars independently from those of Tribosphenida ...
, which would have acquired tribosphenic molars independently from marsupials and placentals. The Jurassic Argentinean ''
Asfaltomylos
''Asfaltomylos'' is an extinct genus of the primitive mammal subclass Australosphenida from the Jurassic of Argentina. The type and only species is ''Asfaltomylos patagonicus'', recovered from and named after the Cañadón Asfalto Formation, Ca ...
'' and ''
Henosferus
''Henosferus'' is an extinct genus of australosphenidan mammal from Lower Jurassic of Argentina. The only recorded species, ''Henosferus molus'', was found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Chubut Province
Ch ...
'' and the Cretaceous Australian ''
Bishops
A bishop is an ordained clergy member who is entrusted with a position of authority and oversight in a religious institution.
In Christianity, bishops are normally responsible for the governance of dioceses. The role or office of bishop is ca ...
'' were later added to Australosphenida, and new work on wear in australosphenidan teeth has called into question whether these animals, including ''Ambondro'', did have tribosphenic teeth. Other paleontologists have challenged this concept of Australosphenida, and instead proposed that ''Ambondro'' is not closely related to ''Ausktribosphenos'' plus monotremes, or that monotremes are not australosphenidans and that the remaining australosphenidans are related to placentals.
Discovery and context
''Ambondro mahabo'' was described by a team led by John Flynn in a 1999 paper in ''
Nature
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
''. The scientific name derives from the village of
Ambondromahabo
Ambondromahabo is a village near Ambondromamy, Boeny, Madagascar.
An extinct mammal from the Jurassic period, ''Ambondro mahabo'', is named after the village, which is close to the locality within the Isalo III geological formation
A geologic ...
, close to which the fossil was found. It is known from the
Bathonian
In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age.
Strat ...
(
middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
, about 167 million years ago) of the
Mahajanga Basin
Mahajanga (French: Majunga) is a city and an administrative district on the northwest coast of Madagascar. The city of Mahajanga (Mahajanga I) is the capital of the Boeny Region. The district (identical to the city) had a population of 220,629 ...
in northwestern Madagascar, in the
Isalo III
The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.Weishampel et al., 2004, pp.542-543 The use of the term "Isalo III" is somewhat controversial as the two prior ...
unit, the youngest of the three rock layers that make up the Isalo "
Group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic ide ...
". This unit has also yielded
crocodyliform
Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...
and
plesiosaur
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
teeth and remains of the sauropod ''
Lapparentosaurus
''Lapparentosaurus'' is a genus of sauropod dinosaur from the Middle Jurassic. Its fossils were found in Madagascar (Isalo III Formation). The type species is ''L. madagascariensis''.
Discovery and naming
In 1895 Richard Lydekker named a new s ...
''.
Description
![Australosphenidan molar labeled](https://upload.wikimedia.org/wikipedia/commons/c/cc/Australosphenidan_molar_labeled.png)
''Ambondro'' was described on the basis of a fragmentary right
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
(lower jaw) with three teeth in it (Figure 1), interpreted as the last
premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
(p-last) and the first two
molars
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
(m1 and m2). It is in the collection of the
University of Antananarivo
University of Antananarivo (french: Université d'Antananarivo) is the primary public university of Madagascar, located in the capital Antananarivo.
History
The university traces its founding to 16 December 1955 and the formation of the Instit ...
as specimen UA 10602. Relative to other primitive mammals, it is small. Each of the teeth has a prominent
cingulum (shelf) on the inner (lingual) side.
[Flynn et al., 1999, p. 58] The p-last has a strong central
cusp
A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth.
Cusp or CUSP may also refer to:
Mathematics
* Cusp (singularity), a singular point of a curve
* Cusp catastrophe, a branch of bifurca ...
. There is a cuspule (small cusp) on the back of the tooth and probably another on the inner front corner. This tooth resembles the molars of
symmetrodonts, a group of primitive mammals, but the back cusp is smaller than the
metaconid
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn ...
of symmetrodonts.
[Flynn et al., 1999, fig. 3]
The front half of the m1 and m2 consists of the
trigonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...
, a group of three cusps forming a triangle: the
paraconid at the front on the inner side,
protoconid
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...
in the middle on the outer (labial) side, and metaconid at the back on the inner side (see Figure 2). The three cusps form a right angle with each other at the protoconid, so that the trigonid is described as "open".
[ The paraconid is higher than the metaconid.][Rauhut et al., 2002, p. 167] At the front margin, a cingulum is present that is divided into two small cusps.[ Unlike in various early tribosphenic mammals and close relatives, there is no additional cuspule behind the metaconid.][Flynn et al., 1999, fig. 2] At the back of the trigonid, the crest known as the distal metacristid
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
is located relatively close to the outer side of the tooth and is continuous with another crest, the cristid obliqua, which is in turn connected to the back of the tooth.[
The ]talonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
, another group of cusps, makes up the back of the tooth. It is wider than long[ and contains a well-developed cusp, the ]hypoconid
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn ...
, on the outer side and a depression, the talonid basin, in the middle. The cristid obliqua connects to the hypoconid. The smaller hypoconulid cusp is present towards the inner side of the tooth, and the hypoconid and hypoconulid are connected by a cutting edge which is suggestive of the presence of a metacone
A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth.
The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two ...
cusp on the upper molars. Further towards the inner side, a crest, the entocristid, rims the talonid basin; on m1, it is swollen and on m2, it contains two small cuspules, but a distinct entoconid
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...
cusp is absent.[ This entocristid is continuous with the lingual cingulum.][
Wear facets are areas of a tooth that show evidence of contact with a tooth in the opposing jaw when the teeth are brought together (known as ]occlusion
Occlusion may refer to:
Health and fitness
* Occlusion (dentistry), the manner in which the upper and lower teeth come together when the mouth is closed
* Occlusion miliaria, a skin condition
* Occlusive dressing, an air- and water-tight trauma ...
). Flynn and colleagues identified two wear facets at the front and back margins of the talonid basin; they argue that these wear facets suggest the presence of a protocone
A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth.
The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two ...
(another cusp on the outer side of the tooth) on the upper molars.[Flynn et al., 1999, p. 59] In a 2005 paper on ''Asfaltomylos
''Asfaltomylos'' is an extinct genus of the primitive mammal subclass Australosphenida from the Jurassic of Argentina. The type and only species is ''Asfaltomylos patagonicus'', recovered from and named after the Cañadón Asfalto Formation, Ca ...
'', a related primitive mammal from Argentina, Thomas Martin and Oliver Rauhut disputed the presence of these wear facets within the talonid basin in ''Ambondro'' and instead identified wear facets on the cusps and crests surrounding the basin. They proposed that wear in the australosphenidan talonid occurs mainly on the rims, not in the talonid basin itself, and that australosphenidans may not have had a functional protocone.[Martin and Rauhut, 2005, pp. 422–423]
Interpretations
In their paper, Flynn and colleagues described ''Ambondro'' as the oldest mammal with tribosphenic molar
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
s—the basic molar type of metatheria
Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well ...
n (marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...
s and their extinct relatives) and eutheria
Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials.
Eutherians are distinguished from noneutherians by various phenotypic tra ...
n (placental
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsup ...
s and their extinct relatives) mammals, characterized by the protocone cusp on the upper molars contacting the talonid basin on the lower molars in chewing. The discovery of ''Ambondro'' was thought to extend the known temporal range of tribosphenic mammals 25 million years further into the past. Consequently, Flynn and colleagues argued against the prevailing view that tribosphenic mammals originated on the northern continents (Laurasia
Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
), and instead proposed that their origin lies in the south (Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
).[Flynn et al., 1999, p. 60] They cited the retention of a distal metacristid and an "open" trigonid as characters separating ''Ambondro'' from more modern tribosphenidans.[
In 2001, Zhe-Xi Luo and colleagues alternatively proposed that a tribosphenic molar pattern had arisen twice (compare Figure 3, top)—once giving rise to the marsupials and placentals (]Boreosphenida
Tribosphenida is a group (infralegion) of mammals that includes the ancestor of ''Hypomylos'', Aegialodontia and Theria (the last common ancestor of marsupials and placentals plus all of its descendants). Its current definition is more or less sy ...
), and once producing ''Ambondro'', the Cretaceous Australian ''Ausktribosphenos
''Ausktribosphenos'' is an extinct genus of mammals from Early Cretaceous of Australia. The only recorded species, ''Ausktribosphenos nyktos'', was found on Flat Rocks, Victoria
Victoria most commonly refers to:
* Victoria (Australia), a st ...
'', and the living monotreme
Monotremes () are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals (Eutheria), and marsupials (Metatheria). Monotremes are typified by structural differences in their brain ...
s, which first appeared in the Cretaceous (united as Australosphenida
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. They are thought to have acquired their tribosphenic molars independently from those of Tribosphenida ...
). They characterized Australosphenida by the shared presence of a cingulum on the outer front corner of the lower molars, a short and broad talonid, a relatively low trigonid, and a triangulated last lower premolar.
Also in 2001, Denise Sigogneau-Russell and colleagues in their description of the earliest Laurasian tribosphenic mammal, '' Tribactonodon'', agreed with the relationship between ''Ausktribosphenos'' and monotremes, but argued that ''Ambondro'' was closer to Laurasian tribosphenidans than to ''Ausktribosphenos'' and monotremes. As evidence against the integrity of Australosphenida, they cited the presence of lingual cingula in various non-australosphenidan mammals; the presence of two cusps in the anterior cingulum in ''Ambondro'' as well as some boreosphenidans; the different appearance of the premolar in ''Ambondro'' (flat) and ''Ausktribosphenos'' (squared); and the contrast between the talonids of ''Ambondro'' (with a well-developed hypoconid on the labial side) and ''Ausktribosphenos'' (squared).[Sigogneau-Russell et al., 2001, p. 146]
The next year, Luo and colleagues published a more thorough analysis confirming their previous conclusion and adding the Cretaceous Australian ''Bishops
A bishop is an ordained clergy member who is entrusted with a position of authority and oversight in a religious institution.
In Christianity, bishops are normally responsible for the governance of dioceses. The role or office of bishop is ca ...
'' to Australosphenida. They mentioned the condition of the hypoconulid, which is inclined forward, rather than backward as in boreosphenidans, as an additional australosphenidan character and noted that ''Ausktribosphenos'' and monotremes were united, to the exclusion of ''Ambondro'', by the presence of a V-shaped notch in the distal metacristid. In the same year, ''Asfaltomylos'' was described from the Jurassic of Argentina as another australosphenidan. In contrast to ''Ambondro'', this animal lacked a distal metacristid and did not have as well-developed a lingual cingulum.
However, in 2003 Michael Woodburne and colleagues revised the phylogenetic analysis
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
published by Luo and colleagues, making several changes to the data, particularly in the monotremes. Their results (Figure 3, bottom) challenged the division between Australosphenida and Boreosphenida, as proposed by Luo et al. Instead, they excluded monotremes from Australosphenida and placed the remaining australosphenidans close to Eutheria, with ''Ambondro'' most closely related to ''Asfaltomylos''. In 2007, Guillermo Rougier and colleagues described another australosphenidan, ''Henosferus
''Henosferus'' is an extinct genus of australosphenidan mammal from Lower Jurassic of Argentina. The only recorded species, ''Henosferus molus'', was found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Chubut Province
Ch ...
'', from the Jurassic of Argentina; they argued against a relationship between Eutheria and Australosphenida (Figure 3, top), but were ambivalent about the placement of monotremes within Australosphenida. Based in part on Martin and Rauhut's earlier work on wear facets in australosphenidans, they questioned the presence of a true functional protocone on the upper molars of non-monotreme australosphenidans—none of which are known from upper teeth—and consequently suggested that australosphenidans may not, after all, have had truly tribosphenic teeth.[Rougier et al., 2007, pp. 24–25]
Notes
References
Bibliography
* Flynn, J.J., Parrish, J.M., Rakotosamimanana, B., Simpson, W.F. and Wyss, A.R. 1999
A Middle Jurassic mammal from Madagascar
(subscription required). ''Nature'' 401:57–60.
* Luo, Z.-X., Cifelli, R.L. and Kielan-Jaworowska, Z. 2001
(subscription required). ''Nature'' 409:53–57.
* Luo, Z.-X., Kielan-Jaworowska, Z. and Cifelli, R.L. 2002
''Acta Palaeontologica Polonica'' 47(1):1–78.
* Martin, T. and Rauhut, O.W.M. 2005
Mandible and dentition of ''Asfaltomylos patagonicus'' (Australosphenida, Mammalia) and the evolution of tribosphenic teeth
(subscription required). ''Journal of Vertebrate Paleontology'' 25(2):414–425.
* Rauhut, O.W.M., Martin, T., Ortiz-Jaureguizar, E. and Puerta, P. 2002
(subscription required). ''Nature'' 416:165–168.
* Rougier, G.W., Martinelli, A.G., Forasiepi, A.M. and Novacek, M.J. 2007
New Jurassic mammals from Patagonia, Argentina: A reappraisal of australosphenidan morphology and interrelationships
''American Museum Novitates'' 3566:1–54.
* Sigogneau-Russell, D., Hooker, J.J. and Ensom, P.C. 2001
The oldest tribosphenic mammal from Laurasia (Purbeck Limestone Group, Berriasian, Cretaceous, UK) and its bearing on the 'dual origin' of Tribosphenida
(subscription required). ''Comptes Rendus de l'Académie des Sciences'', Series IIA (Earth and Planetary Science) 333(2):141–147.
* Woodburne, M.O. 2003
Monotremes as pretribosphenic mammals
(subscription required). ''Journal of Mammalian Evolution'' 10(3):195–248.
* Woodburne, M.O., Rich, T.H. and Springer, M.S. 2003
The evolution of tribospheny and the antiquity of mammalian clades
(subscription required). ''Molecular Phylogeny and Evolution'' 28(2):360–385.
{{DEFAULTSORT:Ambondro (Genus)
Australosphenida
Jurassic mammals of Africa
Jurassic Madagascar
Fossils of Madagascar
Fossil taxa described in 1999