Pantodonta is an extinct

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

(or, according to some, an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

) of

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 ...

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 ...

s. These herbivorous mammals were one of the first groups of large mammals to evolve (around 66 million years ago) after the end of the Cretaceous. The last pantodonts died out at the end of the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

(around 34 million years ago). Pantodonta include some of the largest mammals of their time, but were a diversified group, with some primitive members weighing less than and the largest more than . The earliest and most primitive pantodonts, ''

Bemalambda ''Bemalambda'' is an extinct mammal, belonging to the pantodonts. It lived in the lower-middle Paleocene (about 63–58 million years ago) and the fossil remains have been found in China. Description It was a medium-size animal, and could rea ...

'' (with a skull probably the size of a dog) and '' Hypsilolambda'', appear in the early

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pala ...

Shanghuan Formation in China. All more derived families are collectively classified as Eupantodonta. The pantodonts appear in North America in the middle Paleocene, where '' Coryphodon'' survived into the middle Eocene. Pantodont teeth have been found in South America (''

Alcidedorbignya ''Alcidedorbignya'' is an extinct pantodont mammal known from the Early Paleocene ( Tiupampan SALMA, ) Santa Lucia Formation (, paleocoordinates ) at Tiupampa near Mizque, Cochabamba, Bolivia. Following a naming convention established by p ...

'') and Antarctica, and footprints in a coal mine on

Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group rang ...

Description

The pantodonts varied considerably in size: the small '' Archaeolambda'', of which there is a complete skeleton from the Late Palaeocene of China, was probably arboreal, while the North American, ground sloth-like ''

Barylambda ''Barylambda'' (Greek: "heavy" (baros), "lambda" (lambda) in a reference to larger size than that of '' Pantolambda'') is an extinct genus of pantodont mammal from the middle to late Paleocene, well known from several finds in the Wasatchian ( N ...

'' was massive, slow-moving (" graviportal") and probably browsed on high vegetation.

Dentition

The pantodonts have a primitive

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolog ...

() with little or no diastemata. Their most important

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

are the zalambdodont (V-shaped ectoloph opening towards lip) P^3–4 and (except in the most primitive families) dilambdodont (W-shaped ectoloph) upper molars. Most pantodonts lacked a hypocone (fourth cusp) and had small conules (additional small cusps). The incisors are small but the canines large, occasionally sabertooth-like. On P³-M³ there is normally an ectoflexus (indentation on the outer side). Asian families can typically be distinguished from the American because their paracone and metacone (bottom of W on side of tongue) tend to be closer together. The cheek teeth in the lower jaw are also dilambdodont, with broad, high metalophids (posterior crest) and tall metaconid (posterior-interior cusp) with much lower paracristids and small paraconids.

Postcranial skeleton

Pantodonts have

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and ...

(unaltered) and robust postcranial skeletons. Their five-toed feet are often hoofed with the tarsals similar to those of

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...

s, which feature had led to previously suggested ties to arctocyonid "

condylarth Condylarthra is an informal group – previously considered an order – of extinct placental mammals, known primarily from the Paleocene and Eocene epochs. They are considered early, primitive ungulates. It is now largely considered to be a waste ...

s", but this similarity is now considered primitive.

Classification

The pantodonts were previously grouped with the ungulates as amblypods, paenungulates, or arctocyonids, but since they have been allied with the tillodonts and considered to be derived from the cimolestids. The interrelationship within Pantodonta is controversial, but, following , it contains about two dozen genera in ten families. Most of the families are known from the Paleocene of either Asia or North America. The pantolambdodontids and coryphodontids survived into the Eocene and the latter are known from across the northern hemisphere. Some dental features can possibly link the most primitive pantodonts to the palaeoryctids, a group of small and insectivorous mammals that evolved during the Cretaceous. Recently a close relationship with

Periptychidae Periptychidae is a family of Paleocene placental mammals, known definitively only from North America. The family is part of a radiation of early herbivorous and omnivorous mammals formerly classified in the extinct order "Condylarthra", which ma ...

has been suggested. This would make pantodonts crown-group

placentals and not related to cimolestids at all. Genera from North America tended to be large and robust, starting with ''Pantolambda'' and ''Caenolambda'' in the Middle Paleocene epoch, and later in the epoch started to get larger, with ''Barylambda'' as the largest Paleocene form of pantodont. However, Asian forms, such as ''Archaeolambda'', tended to be thinner and less robust, around the size of a medium-sized dog. Only later in the Eocene, with ''Hypercoryphodon'', did Asian pantodonts get large and robust. File:Barylambda NT small.jpg, Life reconstruction of ''Barylambda faberi'' File:Pantolambda NT copy.jpg, Life reconstruction of ''Pantolambda bathmodon'' File:Titanoides.jpg, Restoration of '' Titanoides primaevus''

Timeline of genera

ImageSize = width:850px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-66 till:-23.03 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:10 start:-60 ScaleMinor = unit:year increment:1 start:-66 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:paleogene value:rgb(0.99,0.6,0.32) id:paleocene value:rgb(0.99,0.65,0.37) id:eocene value:rgb(0.99,0.71,0.42) id:oligocene value:rgb(0.99,0.75,0.48) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -66 till: -56 color:paleocene text:

from: -56 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

bar:eratop from: -66 till: -23.03 color:paleogene text:

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya) to the beginning o ...

PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:paleocene bar:NAM1 from:-64 till:-61 text:

color:paleocene bar:NAM2 from:-63 till:-57 text:

Pantolambda ''Pantolambda'' (Greek: "all" (pantos), "lambda" (lambda), in a reference to the shape of upper premolars, similar to the Greek letter lambda) is an extinct genus of Paleocene pantodont mammal. ''Pantolambda'' lived during the middle Paleocene, a ...

color:paleocene bar:NAM3 from:-60 till:-50 text:

color:paleocene bar:NAM4 from:-59 till:-56 text: Titanoides color:paleocene bar:NAM5 from:-57 till:-46 text: Coryphodon color:eocene bar:NAM6 from:-37 till:-34 text: Hypercoryphodon PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -66 till: -56 color:paleocene text:

from: -56 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

bar:era from: -66 till: -23.03 color:paleogene text:

References

* * * * *

Footnotes

External links

Paleocene-Mammals
{{Taxonbar, from=Q132156 Mammal suborders Priabonian extinctions Paleocene first appearances Fossil taxa described in 1873 Taxa named by Edward Drinker Cope Prehistoric animal suborders