Dryolestida
Encyclopedia
Dryolestida is an extinct order of mammals known from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 to Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...

. It has been suggested that these mammals are either the possible ancestors of therian mammals
Theria
Theria is a subclass of mammals that give birth to live young without using a shelled egg, including both eutherians and metatherians . The only omitted extant mammal group is the egg-laying monotremes....

 or an offshoot from the same evolutionary line
Trechnotheria
Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was endemic to what would be Asia and Africa...

. It is also believed that they developed a fully mammalian jaw and also had the three middle ear bones. Other than that, not much is known about them, this is because their fossils are made up mostly of jaw and tooth remains.

The Dryolestids were formerly considered part of Pantotheria
Pantotheria
Pantotheria is an abandoned taxon of Mesozoic mammals. This group is now considered an informal "wastebasket" taxon and has been replaced by Dryolestida as well as other groups...

 and/or Eupantotheria. The clade Quirogatheria, erected by José Bonaparte
José Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...

 in 1992, is often used as a synonym for Dryolestida. Originally, Quirogatheria was meant to include Brandoniidae, but this family is now included with the Dryolestids.

Classification

Classification modified after Rougier & Gaetano, 2011.
  • Dryolestidae
    Dryolestidae
    Dryolestidae was an abundant and diverse group of Mesozoic mammals. These mammals were different from their relatives by having the following two characteristics:*Their upper and lower molars were shortened mesiodistally and widened labiolingually....

    • Dryolestes
      Dryolestes
      Dryolestes is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zones 2, 5, and 6.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation-References:...

    • Amblotherium
      Amblotherium
      Amblotherium is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zones 2, 3, and 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation-References:...

    • Comotherium
      Comotherium
      Comotherium is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation...

    • Crusafontia
      Crusafontia
      Crusafontia is an extinct genus of Mesozoic mammal.Crusafontia was a 10 cm long creature that may have looked and lived like a squirrel, but this is uncertain, as only a few teeth have ever been found....

    • Groebertherium
    • Guimarotodus
    • Henkelotherium
      Henkelotherium
      Henkelotherium is an extinct genus of mammal from the Late Jurassic Camadas de Guimarota. It differs from most other paurodontids in having more postcanine teeth.-See also:* Prehistoric mammal** List of prehistoric mammals...

    • Krebsotherium
    • Laolestes
      Laolestes
      Laolestes is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zones 5 and 6.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation-References:...

    • Peraspalax
    • Phascolestes
    • Portopinheirodon
  • Paurodontidae
    Paurodontidae
    Paurodontidae is a family of Late Jurassic to Early Cretaceous mammals in the order Dryolestida. Remains of paurodontids have been found in the USA, Britain, Portugal, and Tanzania....

    • Paurodon
      Paurodon
      Paurodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation-References:...

    • Araeodon
      Araeodon
      Araeodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation...

    • Archaeotrigon
      Archaeotrigon
      Archaeotrigon is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation...

    • ?Brancatherulum
      Brancatherulum
      Brancatherulum is an extinct genus of Late Jurassic mammal from the Tendaguru Formation of Tanzania. It is Based on a single toothless dentary.-See also:* Prehistoric mammal** List of prehistoric mammals...

    • Dorsetodon
      Dorsetodon
      Dorsetodon is an extinct genus of mammal from the Early Cretaceous Purbeck Group of Britain. It is represented by isolated lower molars.-See also:* Prehistoric mammal** List of prehistoric mammals...

    • Drescheratherium
      Drescheratherium
      Drescheratherium is an extinct genus of mammal from the Late Jurassic Camadas de Guimarota of Leiria, Portugal. It is represented by fairly complete upper jaws with teeth.-See also:* Prehistoric mammal** List of prehistoric mammals...

    • Euthlastus
      Euthlastus
      Euthlastus is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zones 5 and 6. It is represented by only five upper molars.-See also:* Prehistoric mammal...

    • Foxraptor
      Foxraptor
      Foxraptor is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 6.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation...

    • Tathiodon
      Tathiodon
      Tathiodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.Present in stratigraphic zone 5.-See also:* Prehistoric mammal** List of prehistoric mammals* Paleobiota of the Morrison Formation...

  • †Meridiolestida
    • Cronopio
      Cronopio
      A cronopio is a type of fictional person appearing in works by Argentine writer Julio Cortázar .Together with famas and esperanzas , cronopios are the subject of several short stories in his 1962 book Historias de cronopios y de famas and Cortazar continued to write about cronopios, famas, and...

    • Leonardus
    • †Austrotriconodontidae
      • Austrotriconodon
    • †Brandoniidae
      • Brandonia
      • Alamitherium
      • Barberenia
      • Casamiquelia
      • Rougiertherium
    • †Donodontidae
      • Donodon
        Donodon
        Donodon is an extinct genus of mammal from the Early Cretaceous Séquence B des Couches Rouges of Talssint, Morocco. It is the only member of the family Donodontidae. It differs from dryolestids in having upper molars that are not compressed mesiodistally.-See also:* Prehistoric mammal** List of...

    • †Mesungulatoidea
      • †Mesungulatidae
        • Mesungulatum
        • Coloniatherium
          Coloniatherium
          Coloniatherium is a dryolestoid mammal from the Late Cretaceous of Argentina. The single species, Coloniatherium cilinskii, was a large member of the family Mesungulatidae.-Taxonomy:...

        • Parungulatum
        • Quirogatherium
      • †Peligrotheriidae
        • Peligrotherium
          Peligrotherium
          Peligrotherium is an extinct dryolestid from the Paleocene of Patagonia. Originally, it was thought to be a condylarth. Its remains have been found the Salamanca Formation.-External links:* http://cat.inist.fr/?aModele=afficheN&cpsidt=1120659...

      • †Reigitheriidae
        • Reigitherium
          Reigitherium
          Reigitherium bunodontum is a mammal that lived during the Late Cretaceous . Fossils of it have been found in the Los Alamitos and the La Colonia Formations of Argentina....


Further reading

Zofia Kielan-Jaworowska, Richard L. Cifelli, and Zhe-Xi Luo, Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure (New York: Columbia University Press, 2004), 14, 379-393.

The Illustrated Encyclopedia of the Prehistoric World page 344.
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