Tillodont
   HOME

TheInfoList



OR:

Tillodontia is an extinct suborder 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 ...
n mammals known from the
Early Paleocene The Danian is the oldest age (geology), age or lowest stage (stratigraphy), stage of the Paleocene Epoch or series (stratigraphy), Series, of the Paleogene Period or system (stratigraphy), System, and of the Cenozoic Era or Erathem. The beginnin ...
to
Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...
of China, the
Late Paleocene The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...
to
Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...
of North America where they display their maximum species diversity, the
Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...
of
Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...
, and the Early Eocene of
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 ...
. Leaving no descendants, they are most closely related to the
pantodonts Pantodonta is an extinct suborder (or, according to some, an Order (biology), order) of eutherian mammals. These herbivorous mammals were one of the first groups of large mammals to evolve (around 66 million years ago) after the K-T boundary, en ...
, another extinct group. The tillodonts were medium- to large-sized animals that probably fed on roots and tubers in temperate to subtropical habitats.


Description

Tillodonts had rodent-like incisors, clawed feet and blunt, cusped teeth. They were mostly medium-sized animals, although the largest of them (such as '' Trogosus)'' could reach the size of a large bear. The cranium ranged in length from and had a characteristic elongated
rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...
, an elongated
mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...
, and a shortened basicranial region. The second upper and lower incisors are large in most species, the first upper and lower premolars are small or absent, the fourth upper and lower premolars are molariform (molar-like). When
Marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
first named and described the tillodonts, he explained: When naming his new " pachyderm" species ''Trogosus castoridens'' ("beaver-toothed gnawing-hog"), Leidy added that it was a fossil "which would appear to have pertained to the stock from which diverged the Rhinoceros and Mastodon, the Peccary, and perhaps the Beaver."


Classification

'' Franchaius'' from the early Eocene of Europe, '' Benaius'', '' Lofochaius'', '' Meiostylodon'', and '' Huananius'' from the early Paleocene of China, and '' Yuesthonyx'' from the late Paleocene of China are primitive forms. '' Interogale'' from the late Paleocene of China, and '' Anchilestes'' probably from the middle Paleocene of China, were once assigned to
Anagalida Anagaloidea is a former order of extinct placental mammals that first appeared during the Paleocene epoch. Taxonomy According to the traditional (morphological) view, Anagaloidea is part of the superorder Anagalida, along with the elephant shrew ...
, but may also be primitive tillodonts. The monophyly of the subfamily Trogosinae is unchallenged, but Esthonychines most likely includes the ancestors of Trogosinae and therefore is probably paraphyletic. Tillodontia is mostly known from dentaries and teeth. The cranium is best known from Trogosinae and the postcranium from ''Trogosus''. '' Azygonyx'' and '' Esthonyx'' from North America, '' Franchaius'' and '' Plesiesthonyx'' from Europe, and '' Basalina'' from Pakistan are all morphologically closely related but obviously geographically quite widespread. In contrast, Asian tillodonts tend to be smaller and less derived. This possible link between specimens from Pakistan and Europe with those from North America adds evidence to a faunal interchange between these continents during the early Eocene. Order Tillodontia : Genus †'' Azygonyx'' (), dentary, postcranial fragments : Genus †'' Basalina'' (), poorly preserved jaw fragment with incomplete cheek tooth : Genus †'' Benaius'' (), left lower jaw : Genus †'' Chungchienia'' (), : Genus †'' Dysnoetodon'' (), maxilla and lower jaw : Family † Esthonychidae () (Syn. Anchippodontidae, Tillotheriidae) :: Genus †'' Adapidium'' (), right lower jaw :: Subfamily † Esthonychinae () ::: Genus †'' Esthonyx'' (), lower mandibles, teeth :: Genus †'' Megalesthonyx'' (), left mandible, teeth, feet bones :: Subfamily † Trogosinae () (Syn. Anchippodus) ::: Genus †'' Tillodon'' (), skull ::: Genus †'' Trogosus'' () (Syn. ''Tillotherium''), skull, lower jaws, teeth, vertebrae, ilium, limb bones, feet bones : Genus †'' Franchaius'' (; synonymized with ''Plesiesthonyx'', ), less than 20 isolated teeth : Genus †'' Higotherium'' (), fragmentary right mandible, teeth : Genus †'' Interogale'' (), well-preserved mandible : Genus †'' Kuanchuanius'' (), partial mandible, teeth : Genus †'' Lofochaius'' (), poorly preserved skull with few teeth : Genus †'' Meiostylodon'' (), three isolated teeth : Genus †'' Plesiesthonyx'' (), isolated molars : Genus †'' Plethorodon'' (), partial skull with upper cheek teeth : Genus †'' Simplodon'' (), right upper jaw with cheek teeth : Family † Yuesthonychidae () :: Genus †'' Yuesthonyx'' (), left mandibles, partial skull, teeth


Notes


References

* * * * * * * * * * * * * * * * * * * * * * * * * * {{Taxonbar, from=Q2280456 Clawed herbivores Taxa named by Othniel Charles Marsh Paleocene first appearances Eocene extinctions Mammal suborders Prehistoric animal suborders