Deltatheroida

Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials.[2] The majority of known members of the group lived in the Cretaceous; one species, Gurbanodelta kara, is known from the late Paleocene (Gashatan) of China.[3] Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to Deltatheridium than to Marsupialia.

These mammals possessed tritubercular (three-cusped) lower molars and these were not tribosphenic and were quite primitive. This is awkward because tribosphenic molars are commonly found in most therian mammals (there exist some exceptions such as anteaters and some whales, which have no teeth at all).

When they were first identified in the 1920s, they were believed to be placentals and possible ancestors of the "creodonts" (a polyphyletic group of extinct carnivorous mammals from the Paleogene and Miocene), but this was later disproven. Nonetheless, deltatheroideans do converge on hyaenodontids, oxyaenids, carnivorans, dasyuromorphs and sparassodonts in many details of their dental anatomy, suggesting a carnivorous lifestyle.[4]

Deltatheroida
Temporal range: Aptian–Paleocene
Early Cretaceous-Paleocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Metatheria
Order: Deltatheroida
Gregory and Simpson, 1926
Families & Genera

Taxonomy

The following is a species list of Deltatheroida.[5][6]

†Deltatheroida Kielan-Jaworowska 1982 [Deltatheralia Marshall & Kielan-Jaworowska 1992; Holarctidelphia Szalay 1993]

Biology

Deltatheroideans are thought to be carnivorous mammals, converging on hyaenodontids, oxyaenids, carnivorans, dasyuromorphs and sparassodonts in many details of their dental anatomy, suggesting a carnivorous lifestyle.[4][8]

Deltatheroideans in this regard appear to have replaced eutriconodont mammals as the dominant carnivorous mammals of the Mesozoic, either directly through competition or occupying vacant ecological niches; in North America, Nanocuris came to succeed the larger gobiconodontids and Jugulator, while in Asia the Early Cretaceous gobiconodontid radiation is replaced in the Late Cretaceous by a deltatheroidean one.[9] Given that all insectivorous and carnivorous mammals groups suffered heavy losses during the mid-Cretaceous, it seems likely these metatherians simply occupied niches left after the extinction of eutriconodonts.[10]

Evidence of direct predation on dinosaurs may be attested on a skull belonging to Archaeornithoides, which seems to have been punctured by Deltatheridium teeth and later healed.[11]

At least some deltatheroideans were sabertoothed predators.[7]

See also

References

  1. ^ a b Guillermo W. Rougier; Brian M. Davis; Michael J. Novacek (2015). "A deltatheroidan mammal from the Upper Cretaceous Baynshiree Formation, eastern Mongolia". Cretaceous Research. 52, Part A: 167–177. doi:10.1016/j.cretres.2014.09.009.
  2. ^ Wilson, G.P.; Ekdale, E.G.; Hoganson, J.W.; Calede, J.J.; Linden, A.V. (2016). "A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials". Nature Communications. 7: 13734. doi:10.1038/ncomms13734. PMC 5155139. PMID 27929063.
  3. ^ Xijun Ni; Qiang Li; Thomas A. Stidham; Lüzhou Li; Xiaoyu Lu; Jin Meng (2016). "A late Paleocene probable metatherian (?deltatheroidan) survivor of the Cretaceous mass extinction". Scientific Reports. 6: Article number 38547. doi:10.1038/srep38547. PMC 5141426.
  4. ^ a b CHRISTIAN DE MUIZON and BRIGITTE LANGE-BADRÉ, Carnivorous dental adaptations in tribosphenic mammals and phylogenetic reconstruction, Article first published online: 29 MAR 2007 DOI: 10.1111/j.1502-3931.1997.tb00481
  5. ^ Mikko's Phylogeny Archive [1] Haaramo, Mikko (2007). "†Deltatheroida – deltatherids". Retrieved 30 December 2015.
  6. ^ Paleofile.com (net, info) "Archived copy". Archived from the original on 2016-01-11. Retrieved 2015-12-30.CS1 maint: archived copy as title (link). "Taxonomic lists- Mammals". Archived from the original on 11 January 2016. Retrieved 30 December 2015.
  7. ^ a b S. Bi, X. Jin, S. Li and T. Du. 2015. A new Cretaceous metatherian mammal from Henan, China. PeerJ 3:e896
  8. ^ Zofia Kielan-Jaworowska; Richard L. Cifelli; Zhe-Xi Luo (2004). "Chapter 12: Metatherians". Mammals from the Age of Dinosaurs: origins, evolution, and structure. New York: Columbia University Press. pp. 425–262. ISBN 0-231-11918-6.
  9. ^ G. W. Rougier, B. M. Davis, and M. J. Novacek. 2015. A deltatheroidan mammal from the Upper Cretaceous Baynshiree Formation, eastern Mongolia. Cretaceous Research 52:167-177
  10. ^ David M. Grossnickle, P. David Polly, Mammal disparity decreases during the Cretaceous angiosperm radiation, Published 2 October 2013.DOI: 10.1098/rspb.2013.2110
  11. ^ Elżanowski, A. Wellnhoffer, P. (1993). "Skull of Archaeornithoides From the Upper Cretaceous of Mongolia". earth.geology.yale.edu/~ajs/1993/11.1993.08Elzanowski.pdf . American Journal of Science

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), 444-448.

Atokatheridium

Atokatheridium is an extinct genus of Deltatheridiidae from Cretaceous of United States.

Barylambdidae

Barylambdidae is an extinct family of pantodont mammals from North America.

Comodon

Comodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.

Present in stratigraphic zone 5.

Deltatheridiidae

Deltatheridiidae is an extinct family of basal carnivorous metatherians that lived in the Cretaceous and were closely related to marsupials. Their fossils are restricted to Central Asia (Mongolia and Uzbekistan) and North America (United States - Oklahoma, Texas, Utah, Wyoming). They mostly disappeared in the KT event, but a ghost lineage, currently represented by Gurbanodelta, survived until the late Paleocene by decreasing in size and becoming insectivorous.The family consist in six genera:

Atokatheridium Kielan-Jaworowska & Cifelli, 2001

Deltatheridium Gregory & Simpson, 1926

Deltatheroides Gregory & Simpson, 1926

Gurbanodelta X. Ni et al. 2016

Lotheridium S. Bi et al. 2015

Oklatheridium Davis, Cifelli & Kielan-Jaworowska, 2008

Nanocuris Fox, Scott & Bryant, 2007

Sulestes Nessov, 1985

Tsagandelta G. W. Rougier et al. 2015

Deltatheridium

Deltatheridium (meaning triangle beast or delta beast) is an extinct species of metatherian. It lived in what is now Mongolia during the Upper Cretaceous, circa 80 million years ago. It was a basal metatherian, which places it near start of the lineage that led to the marsupials, such as kangaroos, wallabies, koalas, and opossums.

It had a length of about 15 cm (5.9 in). Its teeth indicate it was carnivorous. One specimen of Archaeornithoides might attest an attack by this mammal, the skull bearing tooth marks that match its teeth.

Deltatheroides

Deltatheroides is an extinct genus of Deltatheridiidae from Cretaceous of Mongolia.

Gurlin Tsav skull

The "Gurlin Tsav" skull is a currently unnamed carnivorous metatherian fossil from the Nemegt Formation of Mongolia. Composed of a single semi-complete skull, this specimen is notable in regards to the evolution and systematics of Metatheria as a whole, and thus nigh-omnipresent in phylogenetic analyses of this group.

Holotheria

Holotheria are a diverse group of mammals that are descendants of the last common ancestor of Kuehneotherium and Theria (the group that includes marsupials and placental mammals).

Khuduklestes

Khukduklestes is a genus of extinct mammal of uncertain affinities from the Late Cretaceous of China. It is rather similar to the also carnivorous and taxonomically uncertain Oxlestes, being slightly smaller.

Leptolambda

Leptolambda is an extinct genus of pantodonts in the family Barylambdidae from North America.

Nanocuris

Nanocuris is an extinct genus of Deltatheridiidae from Cretaceous of Canada (Saskatchewan) and United States (Wyoming - Lance Formation). Initially was classified in a proper family, Nanocuridae, in clade Eutheria, but a reanalysis of a new specimen reveal a deltharoid affinity of the genus.

Oklatheridium

Oklatheridium is an extinct genus of deltatheroidan.

Oxlestes

Oxlestes is an extinct mammal from the Late Cretaceous of Asia, more specifically from the Cenomanian of Uzbekistan. A carnivorous species of uncertain affinities, it is notable for its relatively large size, being among the largest of all Mesozoic mammals. Due to the limited amount of material, it has been considered a nomen dubium.

Palaeosinopa

Palaeosinopa is an extinct genus of semi-aquatic, non-placental eutherian mammals belonging to the family Pantolestidae. Their diet consisted of other semi-aquatic life forms.

Plethorodon

Plethorodon is an extinct genus of tillodont that lived during Early to Late Paleocene. The type species is P. qianshanensis. which known from partial skull and upper teeth that had been discovered by Huang and Zheng at 1987 at Qianshan, Anhui Province, China.

Pucadelphys

Pucadelphys is an extinct genus of non-marsupial metatherian species. The genus contains a single species, P. andinus. Fossils of Pucadelphys have been found in the Santa Lucía Formation in Tiupampa in Bolivia.

Sulestes

Sulestes is an extinct genus of Deltatheridiidae from Cretaceous of Uzbekistan.

Tathiodon

Tathiodon is an extinct genus of Late Jurassic (Kimmeridgian - Tithonian) mammal from the Morrison Formation.

Present in stratigraphic zone 5.

Tsagandelta

Tsagandelta (from "tsagan", Mongolian for white, and "delta", Greek for "crest") is an extinct mammal genus from the Late Cretaceous of Mongolia. Distantly related to modern marsupials, it is part of Deltatheroida, a lineage of carnivorous metatherians common in the Cretaceous of Asia and among the most successful non-theropod carnivores of the region.

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