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Eutriconodonta is an order of early mammals. Eutriconodonts existed in
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,
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,
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,
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north ...
and
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
during the
Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
and 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 ...
periods. The order was named by Kermack ''et al.'' in 1973 as a replacement name for the paraphyletic Triconodonta. Traditionally seen as the classical
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
small mammalian insectivores, discoveries over the years have shown them to be among the best examples of the diversity of mammals in this time period, including a vast variety of bodyplans, ecological niches and locomotion methods.


Classification

"Triconodonta" had long been used as the name for an order of early mammals which were close relatives of the ancestors of all present-day mammals, characterized by molar teeth with three main cusps on a crown that were arranged in a row. The group originally included only the family
Triconodontidae Triconodontidae is an extinct family of small, carnivorous mammals belonging to the order Eutriconodonta, endemic to what would become Asia, Europe, North America and probably also Africa and South America during the Jurassic through Cretaceous p ...
and taxa that were later assigned to the separate family Amphilestidae, but was later expanded to include other taxa such as '' Morganucodon'' or ''
Sinoconodon ''Sinoconodon'' is an extinct genus of mammaliamorphs that appears in the fossil record of the Lufeng Formation of China in the Sinemurian stage of the Early Jurassic period, about 193 million years ago. While sharing many plesiomorphic tra ...
''. The phylogenetic analyses found that all these taxa did not form a natural group, and that some traditional "triconodonts" were more closely related to
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
n mammals than others. Some traditional "triconodonts" do seem to form a natural group (or "clade"), and this was given the name Eutriconodonta, or "true triconodonts). Most analyses use only dental and
mandibular 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 ...
characters. Gao ''et al.'' (2010) conducted a second analysis as well, using a modified version of the matrix from the analysis of Luo ''et al.'' (2007); this analysis involved a broader range of Mesozoic mammaliaforms and more characters, including postcranial ones. Both Luo ''et al.'' (2007) and the second analysis of Gao ''et al.'' (2010) recovered a more inclusive monophyletic Eutriconodonta that also contained gobiconodontids and ''Amphilestes''; in the second analysis of Gao ''et al.'' it also contained '' Juchilestes'' (recovered as amphidontid in their first analysis, the only amphidontid included in their second analysis). However, Gao ''et al.'' (2010) stressed that jeholodentids and gobiconodontids are the only eutriconodonts with known postcranial skeletons; according to the authors, it remains uncertain whether the results of their second analysis represent true phylogeny or are merely "a by-product of
long branch attraction In phylogenetics, long branch attraction (LBA) is a form of systematic error whereby distantly related lineages are incorrectly inferred to be closely related. LBA arises when the amount of molecular or morphological change accumulated within a lin ...
of jeholodentids and gobiconodontids". Phylogenetic studies conducted by Zheng ''et al.'' (2013), Zhou ''et al.'' (2013) and Yuan ''et al.'' (2013) recovered monophyletic Eutriconodonta containing triconodontids, gobiconodontids, ''Amphilestes'', ''Jeholodens'' and ''Yanoconodon''. The exact phylogenetic placement of eutriconodonts within Mammaliaformes is also uncertain. Zhe-Xi Luo, Zofia Kielan-Jaworowska and Richard Cifelli (2002) conducted an analysis that recovered eutriconodonts within the crown group of Mammalia, i.e. the least inclusive clade containing monotremes and
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
n mammals. The analysis found eutriconodonts to be more closely related to therian mammals than monotremes were, but more distantly than (paraphyletic) amphitheriids, dryolestids, spalacotheriid " symmetrodonts" and
multituberculates Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, a ...
were. This result was mostly confirmed by Luo ''et al.'' (2007), the second analysis of Gao ''et al.'' (2010), Zheng ''et al.'' (2013), Zhou ''et al.'' (2013) and Yuan ''et al.'' (2013), although in the phylogenies of Luo ''et al.'' (2007) and Yuan ''et al.'' (2013) eutriconodonts were in unresolved
polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...
with multituberculates and trechnotherians. If confirmed this would make eutriconodonts one of the groups that can be classified as mammals by any definition. Several other extinct groups of
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
animals that are traditionally considered to be mammals (such as Morganucodonta and Docodonta) are now placed just outside Mammalia by those who advocate a 'crown-group' definition of the word "mammal". However, Luo, Kielan-Jaworowska and Cifelli (2002) tested alternative possible phylogenies as well, and found that recovering eutriconodonts outside the crown group of Mammalia required only five additional steps compared to the most parsimonious solution. The authors stated that such placement of eutriconodonts is less likely than their placement within the mammalian crown group, but it cannot be rejected on a statistical basis. The most recent cladogram is by
Thomas Martin Thomas or Tom Martin may refer to: Born 16th century *Thomas Martin (politician, died 1583) (1530–1583), MP for Dorchester * Thomas Martin (lawyer) (1521–1593), MP for Ludgershall, Saltash and Hindon Born 17th century *Thomas Martin of Pa ...
et al. 2015, in their description of ''
Spinolestes ''Spinolestes'' is an extinct mammal genus from the Early Cretaceous of Spain. A gobiconodontid eutriconodont, it is notable for the remarkable degree of preservation, offering profound insights to the biology of non-therian mammals.Thomas Marti ...
''. Eutriconodonts are recovered as a largely monophyletic group within Theriimorpha. A study finds them paraphyletic in regards to crown group
Mammalia 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 o ...
.


Range

When eutriconodonts first appeared is unclear. The earliest remains come from the late Early Jurassic (
Toarcian The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian. The Toarcian ...
), but they already represent a variety of groups: the volaticotherian '' Argentoconodon'', the alticonodontine '' Victoriaconodon'' and the gobiconodontid '' Huasteconodon'', as well as the putative eutriconodont ''" Dyskritodon" indicus''. They achieve their peak diversity across the Early Cretaceous, before largely disappearing from the fossil record in the early
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
outside of North America. The
Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...
genus '' Alticonodon'' is the youngest representative of the group; the
Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...
/
Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...
'' Austrotriconodon'' was originally referred to as a late surviving member of the clade, but has since been moved to Dryolestoidea. Most eutriconodont remains occur in laurasian landmasses. The exceptions are '' Argentoconodon'' and slightly younger '' Condorodon'' from the
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
of
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, the putative '' Dyskritodon indicus'' from the
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
of
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
(
Kota Formation The Kota Formation is a geological formation in India. The precise age of Kota Formation are uncertain, but it dates from the Early to Middle Jurassic, and is split into a Lower Member and Upper Member.Prasad GVR, and Manhas BK. 2007A new docodont ...
), the
Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...
'' Tendagurodon'' from
Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...
(
Tendaguru Formation The Tendaguru Formation, or Tendaguru Beds are a highly fossiliferous formation and Lagerstätte located in the Lindi Region of southeastern Tanzania. The formation represents the oldest sedimentary unit of the Mandawa Basin, overlying Neoproter ...
) and several Early Cretaceous
north Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...
n taxa like '' Ichthyoconodon'', '' Dyskritodon amazighi'' and ''
Gobiconodon ''Gobiconodon'' is an extinct genus of carnivorous mammal from the Middle Jurassic to Early Cretaceous. It weighed , had a skull of in length, and had in presacral body length. It was one of the largest mammals known from the Mesozoic. Like o ...
palaios''. Due to the rarity of the Jurassic gondwanan fossil record the presence of eutriconodonts in southern landmasses may be of interest, due to their comparatively early age. Eutriconodonts are among the few Mesozoic mammals present at Arctic locations;
docodonts Docodonta is an order of extinct mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early mammaliaforms by their relatively complex molar teeth, from which the order ge ...
and haramiyidans (generally considered non-mammalian cynodonts) are also present, but not
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
ns,
dryolestoid Dryolestida is an extinct order of mammals, primarily and possibly exclusively known from the Jurassic and Cretaceous. They are considered members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they ...
s and other groups considered true mammals.


Biology


Anatomy

Like many other non-
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
n mammals, eutriconodonts retained classical mammalian synapomorphies like
epipubic Epipubic bones are a pair of bones projecting forward from the pelvic bones of modern marsupials, monotremes and fossil mammals like multituberculates, and even basal eutherians (the ancestors of placental mammals, who lack them). They first o ...
bones (and likely the associated reproductive constrictions), venomous spurs and sprawling limbs. However, the forelimb and shoulder anatomy of at least some species like '' Jeholodens'' are similar to those of therian mammals, though the hindlimbs remain more conservative. Eutriconodonts had a modern ear anatomy, the main difference from
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
ns being that the ear ossicles were still somewhat connected to the jaw via the
Meckel's cartilage In humans, the cartilaginous bar of the mandibular arch is formed by what are known as Meckel's cartilages (right and left) also known as Meckelian cartilages; above this the incus and malleus are developed. Meckel's cartilage arises from the fir ...
. Uniquely among crown-group mammals, gobiconodontids replaced their molariform teeth by successors of similar complexity, while in other mammals less complex replacements are the norm.


Soft tissues

Some eutriconodonts like ''
Spinolestes ''Spinolestes'' is an extinct mammal genus from the Early Cretaceous of Spain. A gobiconodontid eutriconodont, it is notable for the remarkable degree of preservation, offering profound insights to the biology of non-therian mammals.Thomas Marti ...
'' and '' Volaticotherium'' were very well preserved, showing evidence of fur, internal organs and, in the latter, of patagia. ''Spinolestes'' shows hair similar to that of modern mammals, with compound hair follicles with primary and secondary hair, even preserving traces of a pore infection. It also possesses a clear
thoracic diaphragm The thoracic diaphragm, or simply the diaphragm ( grc, διάφραγμα, diáphragma, partition), is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the m ...
like modern mammals, as well as spines, dermal
scutes A scute or scutum (Latin: ''scutum''; plural: ''scuta'' " shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterio ...
and an ossified
Meckel's cartilage In humans, the cartilaginous bar of the mandibular arch is formed by what are known as Meckel's cartilages (right and left) also known as Meckelian cartilages; above this the incus and malleus are developed. Meckel's cartilage arises from the fir ...
. Furthermore, ''Spinolestes'' may also display signs of dermatophytosis, suggesting that gobiconodontids, like modern mammals, were vulnerable to this type of fungal infection. '' Triconodon'' itself has been the subject to cranial
endocast An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible sp ...
studies, revealing a unique
brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
anatomy.


Paleobiology

The eutriconodont triconodont dentition has no analogue among living mammals, so comparisons are difficult. There are two main types of
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 ...
patterns: one present in triconodontids (as well as the unrelated morganucodontan mammals), in which lower
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 bifurc ...
"a" occludes anterior to upper cusp "A", between "A" and "B", and one present in amphilestids and gobiconodontids, in which the molars basically alternate, with the lower cusp "a" occluding further forward, near the junction between two upper molars. A study on '' Priacodon'' however suggests that only the latter arrangement was present. However, it's clear that most if not all eutriconodonts were primarily carnivorous, given the presence of long, sharp canines, premolars with trenchant main cusps that were well suited to grasp and pierce prey, strong development of the madibular abductor musculature, bone crushing ability in at least some species and several other features. Triconodont teeth are known to have had a shearing function, allowing the animal to tear through flesh much like
carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...
teeth of
theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...
n mammals. In a study about Mesozoic mammalian diets the taxa ''
Repenomamus ''Repenomamus'' (Latin: "reptile" (reptilis), "mammal" (mammalis)) is a genus of opossum- to badger-sized gobiconodontid mammal containing two species, ''Repenomamus robustus'' and ''Repenomamus giganticus''. Both species are known from fossils ...
'', ''
Gobiconodon ''Gobiconodon'' is an extinct genus of carnivorous mammal from the Middle Jurassic to Early Cretaceous. It weighed , had a skull of in length, and had in presacral body length. It was one of the largest mammals known from the Mesozoic. Like o ...
'', '' Argentoconodon'', '' Phascolotherium'', '' Triconodon'' and '' Liaoconodon'' rank among carnivorous mammal species, while '' Volaticotherium'', '' Liaotherium'', '' Amphilestes'' and '' Jeholodens'' ranked among insectivorous mammals, while '' Yanoconodon'', '' Priacodon'' and '' Trioracodon'' ranked somewhere in between. A study on '' Priacodon'' suggests that the jaw roll was more passive for eutriconodonts than modern therian carnivores. Eutriconodonts are often among the largest mammals in Mesozoic faunal assemblages, displaying a broad size range from small
shrew Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to differ ...
-like insectivores to large forms like ''
Repenomamus ''Repenomamus'' (Latin: "reptile" (reptilis), "mammal" (mammalis)) is a genus of opossum- to badger-sized gobiconodontid mammal containing two species, ''Repenomamus robustus'' and ''Repenomamus giganticus''. Both species are known from fossils ...
'', ''
Gobiconodon ''Gobiconodon'' is an extinct genus of carnivorous mammal from the Middle Jurassic to Early Cretaceous. It weighed , had a skull of in length, and had in presacral body length. It was one of the largest mammals known from the Mesozoic. Like o ...
'', '' Triconodon'' and ''
Jugulator ''Jugulator'' is the thirteenth studio album by English heavy metal band Judas Priest. It was released in Japan on 16 October 1997 and the rest of the world on 28 October 1997. It was their first studio album since ''Painkiller'' in 1990 an ...
''. They were among the first mammals to be specialised for vertebrate prey, and likely occupied the highest
trophic Trophic, from Ancient Greek τροφικός (''trophikos'') "pertaining to food or nourishment", may refer to: * Trophic cascade * Trophic coherence * Trophic egg * Trophic function * Trophic hormone * Trophic level index * Trophic level ...
levels among mammals in their faunal communities. Several forms like ''Gobiconodon'' and ''Repenomamus'' show evidence of scavenging, being among the few Mesozoic mammals to have significantly exploited that. At least in carnivorous niches, eutriconodonts were probably replaced by deltatheroidean metatherians, which are the dominant carnivorous mammals in
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
faunal assemblages. Competition between both groups is unattested, but in Asia the Early Cretaceous gobiconodontid diversity is replaced entirely by a deltatheroidean one, while in North America '' Nanocuris'' appears after the absence of ''
Gobiconodon ''Gobiconodon'' is an extinct genus of carnivorous mammal from the Middle Jurassic to Early Cretaceous. It weighed , had a skull of in length, and had in presacral body length. It was one of the largest mammals known from the Mesozoic. Like o ...
'' and other larger eutriconodonts. Given that all insectivorous and carnivorous mammals groups suffered heavy losses during the mid-Cretaceous, it seems likely these metatherians simply occupied niches left after the extinction of eutriconodonts. Some eutriconodonts were instead among the most specialised of Mesozoic mammals. Several taxa like '' Astroconodon'', '' Dyskritodon'' and '' Ichthyoconodon'' may show adaptations for piscivory and occur in aquatic settings with their molars being compared to those of seals and cetaceans. Caution has been advised in these comparisons, however; as many researchers like
Zofia Kielan-Jaworowska Zofia Kielan-Jaworowska (25 April 1925 – 13 March 2015) was a Polish paleobiologist. In the mid-1960s, she led a series of Polish-Mongolian paleontological expeditions to the Gobi Desert. She was the first woman to serve on the executive commit ...
have noted, eutriconodont molars are more functionally similar to those of terrestrial
carnivorans Carnivora is a monophyletic order of placental mammals consisting of the most recent common ancestor of all cat-like and dog-like animals, and all descendants of that ancestor. Members of this group are formally referred to as carnivorans, ...
than
pinnipeds Pinnipeds (pronounced ), commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae (whose only living member is the walru ...
and cetaceans, occluding in a shearing motion instead of not-occluding and providing a grasping function. However, '' Dyskritodon'' and ''Ichthyoconodons teeth shows no erosion associated with aquatic transportation, meaning that the animals died ''in situ'' or close. Studies on '' Liaoconodon'' show that it has adaptations for an aquatic lifestyle, possessing a barrel-like body and paddle-like limbs, and analysis of the postcrania of '' Yanoconodon'' shows adaptations towards multiple forms of locomotion, with traits in common with fossorial, arboreal, and semiaquatic mammals. Additionally, '' Volaticotherium'' and '' Argentoconodon'' show adaptations for aerial locomotion. Both genera are closely related, implying a long lived lineage of gliding mammals. At least ''Spinolestes'' had xenarthrous vertebrae and osseous scutes, convergent to those of modern xenarthrans and to a lesser extent the hero shrew. This genus may have displayed an ecological role similar to that of modern anteaters,
pangolins Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: ''Manis'', ''Phataginus'', and ''Smutsia'' ...
,
echidnas 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 ...
,
aardvark The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlik ...
,
aardwolf The aardwolf (''Proteles cristata'') is an insectivorous species of hyena, native to East and Southern Africa. Its name means "earth-wolf" in Afrikaans and Dutch. It is also called maanhaar-jackal (Afrikaans for " mane-jackal"), termite-eat ...
and
numbat The numbat (''Myrmecobius fasciatus''), also known as the noombat or walpurti, is an insectivorous marsupial. It is diurnal and its diet consists almost exclusively of termites. The species was once widespread across southern Australia, but ...
, being the second known Mesozoic mammal after '' Fruitafossor'' to have done so.


Reproductive biology

'' Triconodon'' shows dental replacement patterns consistent with
milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modula ...
-drinking mammals.


Notes


References

{{Taxonbar, from=Q135419 Mammal orders Maastrichtian extinctions Bathonian first appearances Fossil taxa described in 1973 Taxa named by Kenneth A. Kermack Taxa named by Frances Mussett