Pantodonta is an extinct

suborder Order () 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 recognized ...

(or, according to some, an

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

) of

eutheria Eutheria (from Greek , 'good, right' and , 'beast'; ), also called Pan-Placentalia, is the clade consisting of Placentalia, placental mammals and all therian mammals that are more closely related to placentals than to marsupials. Eutherians ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

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

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

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), ...

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 ''Coryphodon'' (from Greek , "point", and , "tooth", meaning ''peaked tooth'', referring to "the development of the angles of the ridges into points n the molars") is an extinct genus of pantodonts of the family Coryphodontidae. ''Coryphodo ...

'' 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 pio ...

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

Svalbard Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway be ...

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 (Nor ...

'' 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-physiology ...

() with little or no diastemata. Their most important

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

are the

zalambdodont 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 tooth ...

(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, an ...

(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 Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

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

condylarth Condylarthra is an informal group – previously considered an Order (biology), order – of extinct placental mammals, known primarily from the Paleocene and Eocene epochs. They are considered early, primitive ungulates and is now largely consid ...

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 Cretaceous–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 " Condylart ...

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 (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 ...

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

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

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 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:

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 Taxa named by Edward Drinker Cope Prehistoric animal suborders