Palaeanodonta ("ancient toothless animals") is an extinct clade of stem-
pangolin
Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (). The one extant family, the Manidae, has three genera: '' Manis'', '' Phataginus'', and '' Smutsia''. ''Manis'' comprises four species found in Asia, while ' ...
s. They were
insectivorous
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores we ...
(
myrmecophagous), possibly
fossorial
A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...
, and lived from the middle
Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
to early
Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...
in
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
,
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
and
Asia
Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
.
While the taxonomic grouping of Palaeanodonta has been debated,
[Averianov, A. O. & Lopatin, A. V. (2014.]
"High-level systematics of placental mammals: Current status of the problem."
Biology Bulletin, 41(9), 801–816. it is widely thought that they are a
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to
pangolins
Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (). The one extant family, the Manidae, has three genera: ''Manis'', '' Phataginus'', and '' Smutsia''. ''Manis'' comprises four species found in Asia, while ''P ...
.
Anatomy
Skull
Palaeanodonts generally have low and caudally-broad skulls, with notable
lambdoid crests and inflated
bullae and
squamosals.
Teeth
Despite the name of the group and contrary to their pangolin relatives, palaeanodonts are known to have had teeth.
Early palaeanodonts retained minimal
tribosphenic post-canines while later species had peglike or otherwise reduced molar crowns.
Many also had large, characteristic
cuspids.
Classification and phylogeny
Traditional classification
* Order: †Palaeanodonta
(Matthew, 1918) (stem-pangolins)
** Family: †
Epoicotheriidae
Epoicotheriidae ("strange beasts") is an extinct paraphyletic family of insectivorous placental mammals within extinct order Palaeanodonta, that lived in North America, Asia and Europe from the late Paleocene to early Oligocene. Epoicotheriids we ...
(paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
family) (Simpson, 1927)
** Family: †
Escavadodon
''Escavadodon'' ("tooth from Escavada") is an extinct genus of pangolin-like myrmecophagous placental mammals of extinct monotypic family Escavadodontidae within extinct order Palaeanodonta, that lived in North America during the middle Paleoce ...
tidae
(Rose & Lucas, 2000)
** Family: †
Metacheiromyidae
Metacheiromyidae ("next to ''Cheiromys''") is an extinct paraphyletic family of myrmecophagous placental mammals within extinct order Palaeanodonta, that lived in North America and Europe from the late Paleocene to middle Eocene.R. M. Schoch (19 ...
(Wortman, 1903)
** ''
Incertae sedis
or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'':
*** Genus: †''
Arcticanodon''
(Rose, 2004)
*** Genus: †''
Melaniella''
(Fox, 1984)
Revised classification
* Order: †Palaeanodonta
(Matthew, 1918) (stem-pangolins)
** Family: †
Epoicotheriidae
Epoicotheriidae ("strange beasts") is an extinct paraphyletic family of insectivorous placental mammals within extinct order Palaeanodonta, that lived in North America, Asia and Europe from the late Paleocene to early Oligocene. Epoicotheriids we ...
(paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
family) (Simpson, 1927)
*** Genus: †''
Alocodontulum''
(Rose, 1978)
**** †''Alocodontulum atopum''
(Rose, 1977)
*** Genus: †''
Amelotabes''
(Rose, 1978)
**** †''Amelotabes simpsoni''
(Rose, 1978)
*** Genus: †''
Auroratherium''
(Tong & Wang, 1997)
**** †''Auroratherium sinense''
(Tong & Wang, 1997)
*** Genus: †''
Dipassalus''
(Rose, 1991)
**** †''Dipassalus oryctes''
(Rose, 1991)
*** Genus: †''
Tubulodon''
(Jepsen, 1932)
**** †''Tubulodon taylori''
(Jepsen, 1932)
*** Subfamily: †
Epoicotheriinae
Epoicotheriinae ("strange beasts") is an extinct paraphyletic subfamily of insectivorous placental mammals within extinct paraphyletic family Epoicotheriidae in extinct order Palaeanodonta, that lived in North America and Europe from the early Eo ...
(paraphyletic subfamily) (Simpson, 1927)
**** Genus: †''
Pentapassalus''
(Gazin, 1952)
***** †''Pentapassalus pearcei''
(Gazin, 1952)
***** †''Pentapassalus woodi''
(Guthrie, 1967)
**** Genus: †''
Tetrapassalus''
(Simpson, 1959)
***** †''Tetrapassalus mckennai''
(Simpson, 1959)
***** †''Tetrapassalus proius''
(West, 1973)
***** †''Tetrapassalus'' sp. A
'AMNH 10215''(Rose, 1978)
***** †''Tetrapassalus'' sp. B
(Robinson, 1963)
**** (unranked): †''Epoicotherium''/''Xenocranium'' clade
***** Genus: †''
Epoicotherium''
(Simpson, 1927)
****** †''Epoicotherium unicum''
(Douglass, 1905)
***** Genus: †''
Molaetherium''
(Storch & Rummel, 1999)
****** †''Molaetherium heissigi''
(Storch & Rummel, 1999)
***** Genus: †''
Xenocranium
''Xenocranium'' ("strange skull") is an extinct monotypic genus of placental mammal from extinct paraphyletic subfamily Epoicotheriinae within extinct paraphyletic family Epoicotheriidae in extinct order Palaeanodonta, that lived in North Americ ...
''
(Colbert, 1942)
****** †''Xenocranium pileorivale''
(Colbert, 1942)
** Family: †
Ernanodontidae
Ernanodontidae ("sprouts of toothless animals") is an extinct family of Myrmecophagy, myrmecophagous placental mammals within extinct order Palaeanodonta, that lived in Asia from the middle to late Paleocene.Malcolm C. McKenna, Susan K. Bell: ''C ...
(Ting, 1979)
*** Genus: †''
Asiabradypus''
(Nessov, 1987)
**** †''Asiabradypus incompositus''
(Nessov, 1987)
*** Genus: †''
Ernanodon
''Ernanodon'' ("a sprout of toothless animals") is an extinct genus of placental mammal from extinct family Ernanodontidae within extinct order Palaeanodonta, that lived from the middle to late Paleocene in China ( Nongshan Formation) and Mongol ...
''
(Ting, 1979)
**** †''Ernanodon antelios''
(Ting, 1979)
** Family: †
Escavadodon
''Escavadodon'' ("tooth from Escavada") is an extinct genus of pangolin-like myrmecophagous placental mammals of extinct monotypic family Escavadodontidae within extinct order Palaeanodonta, that lived in North America during the middle Paleoce ...
tidae
(Rose & Lucas, 2000)
*** Genus: †''
Escavadodon
''Escavadodon'' ("tooth from Escavada") is an extinct genus of pangolin-like myrmecophagous placental mammals of extinct monotypic family Escavadodontidae within extinct order Palaeanodonta, that lived in North America during the middle Paleoce ...
''
(Rose & Lucas, 2000)
**** †''Escavadodon zygus''
(Rose & Lucas, 2000)
** Family: †
Metacheiromyidae
Metacheiromyidae ("next to ''Cheiromys''") is an extinct paraphyletic family of myrmecophagous placental mammals within extinct order Palaeanodonta, that lived in North America and Europe from the late Paleocene to middle Eocene.R. M. Schoch (19 ...
(paraphyletic family)
*** Genus: †''
Brachianodon''
(Gunnell & Gingerich, 1993)
**** †''Brachianodon westorum''
(Gunnell & Gingerich, 1993)
*** Genus: †''
Mylanodon''
(Secord, 2002)
**** †''Mylanodon rosei''
(Secord, 2002)
*** Subfamily: †
Metacheiromyinae
Metacheiromyidae ("next to ''Cheiromys''") is an extinct paraphyletic family of myrmecophagous placental mammals within extinct order Palaeanodonta, that lived in North America and Europe from the late Paleocene to middle Eocene.R. M. Schoch (19 ...
(paraphyletic subfamily)
**** Genus: †''
Metacheiromys
''Metacheiromys'' ("next to ''Cheiromys''") is an extinct genus of placental mammals from extinct paraphyletic subfamily Metacheiromyinae within extinct paraphyletic family Metacheiromyidae in extinct order Palaeanodonta, that lived in North Ame ...
''
(Wortman, 1903)
***** †''Metacheiromys dasypus''
(Osborn, 1904)
***** †''Metacheiromys marshi''
(Wortman, 1903)
**** Genus: †''
Palaeanodon''
(Matthew, 1918)
***** †''Palaeanodon ignavus''
(Matthew, 1918)
***** †''Palaeanodon nievelti''
(Gingerich, 1989)
***** †''Palaeanodon parvulus''
(Matthew, 1918)
***** †''Palaeanodon'' sp.
e Quesnoy(Gheerbrant, 2005)
*** Subfamily: †
Propalaeanodontinae
(Schoch, 1984)
**** Genus: †''
Propalaeanodon''
(Rose, 1979)
***** †''Palaeanodon parvulus''
(Rose, 1979)
** ''
Incertae sedis
or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'':
*** Genus: †''
Arcticanodon''
(Rose, 2004)
**** †''Arcticanodon dawsonae''
(Rose, 2004)
*** Genus: †''
Melaniella''
(Fox, 1984)
**** †''Melaniella timosa''
(Fox, 1984)
Phylogenetic tree
The phylogenetic relationships of order Palaeanodonta are shown in the following cladogram:
See also
*
Mammal classification
Mammalia is a class of animal within the phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wils ...
*
Pholidotamorpha
Pholidotamorpha ("pangolin-like forms") is a clade of placental, mostly ant- and termite-eating mammals that (partially) physically resemble anteaters and armadillos. However, those aforementioned species are now placed in the order Xenarthra, ...
References
{{Taxonbar, from=Q3889294
Mammal orders
Prehistoric tetrapod orders