Xenocranium

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Xenocranium
Temporal range: 35.8–33.9  Ma
O
S
D
C
P
T
J
K
Pg
N
Late Eocene
Xenocranium NT.jpg
Artist reconstruction of
Xenocranium pileorivale
compared to the size of a human hand.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Palaeanodonta
Family: Epoicotheriidae
Subfamily: Epoicotheriinae
Genus: Xenocranium
Colbert, 1942 [1]
Type species
Xenocranium pileorivale
Colbert, 1942

Xenocranium ("strange skull") is an extinct monotypic genus of placental mammal from extinct paraphyletic subfamily Epoicotheriinae within extinct paraphyletic family Epoicotheriidae in extinct order Palaeanodonta, that lived in North America during the late Eocene.

Contents

Etymology

The name of genus Xenocranium comes from Ancient Greek ξένος (xénos) 'strange' and from Ancient Greek κρανίον (krāníon) 'skull', respectively after its unique skull arrangement.

The specific epithet is derived from Latin pileus 'hat' and from Latin rivalis 'brook', in reference to the nearby township of Hat Creek, Wyoming, U.S.A. [1]

Description

Xenocranium pileorivale was highly specialized animal that was convergent with the talpids, golden moles and marsupial mole. It possesses many traits indicative of the lifestyle of a subterranean burrower, including small eyes, an upturned snout, muscular arms with large attachment points for the triceps, teres major, and carpal and digital flexor muscles. [2] The dental formula is 0.1.41.1.5. [3]

Palaeoecology

The holotype of Xenocranium pileorivale was recovered from the Brule Formation, 160 feet below the top of the Oligocene outcrop in the area, [1] which correlates with the Chadronian age to the Orellan age under the NALMA classification. Later on, this layer was found to be from Priabonian age of late Eocene. Further remains have been found in the White River Formation of Nebraska. [3] The animals from these formations constitute the White River Fauna, which included predators like Archaeotherium and Hyaenodon , and a large diversity of herbivorous mammals, such as the archaic horse Mesohippus , the cursorial rhinoceros Hyracodon , and the very common "oreodont" Merycoidodon . [4]

Phylogenetic tree

The phylogenetic relationships of genus Xenocranium is shown in the following cladogram: [5] [6] [7]

  Ferae  

Pan-Carnivora Dogs, jackals, wolves, and foxes (Plate XI).jpg

  Pholidotamorpha  

Pholidota(sensu stricto) Pangolin Hardwicke (white background).jpg

  Palaeanodonta  

Escavadodontidae

 ? 

Melaniella

Ernanodontidae

Metacheiromys Metacheiromys DB152-2.jpg

Metacheiromyinae  

Palaeanodon

Brachianodon

Mylanodon

Propalaeanodontinae

 ? 

Arcticanodon

Alocodontulum

Auroratherium

Pentapassalus

Tubulodon

Dipassalus

Epoicotheriinae

Tetrapassalus

 Xenocranium 

Xenocranium pileorivale

Epoicotherium

Molaetherium

Epoicotheriidae

Amelotabes

 (Pholidota [sensu lato]) 
Epoicotherium/Xenocranium clade

See also

Related Research Articles

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<i>Metacheiromys</i> Extinct genus of mammal

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<i>Necromanis</i> Extinct genus of mammals

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<i>Ernanodon</i> Extinct genus of mammal

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<span class="mw-page-title-main">Epoicotheriidae</span> Extinct family of mammals

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<i>Patriomanis</i> Genus of mammals

Patriomanis is an extinct genus of pangolin from extinct family Patriomanidae. It lived from the late Eocene to early Oligocene of North America and it currently represents the only pangolin known from the Western Hemisphere. The genus contains one species, P. americana, which is known from six specimens, mostly from the Chadronian White River Formation of Montana. It had long digits and a prehensile tail, suggesting that it was arboreal, and its jaw was capable of opening wider than modern pangolins. Its ears and the hair between its scales were also longer than modern pangolins.

<span class="mw-page-title-main">Palaeanodonta</span> Extinct clade of mammals

Palaeanodonta is an extinct clade of stem-pangolins. They were insectivorous (myrmecophagous), possibly fossorial, and lived from the middle Paleocene to early Oligocene in North America, Europe and Asia. While the taxonomic grouping of Palaeanodonta has been debated, it is widely thought that they are a sister group to pangolins.

<span class="mw-page-title-main">Patriomanidae</span> Extinct family of pangolins

Patriomanidae is an extinct family of pangolins from superfamily Manoidea that includes two extinct genera Patriomanis and Cryptomanis.

<span class="mw-page-title-main">Ernanodontidae</span> Extinct family of mammals

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<i>Euromanis</i> Genus of mammals

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<span class="mw-page-title-main">Palaeonictinae</span> Extinct subfamily of mammals

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<span class="mw-page-title-main">Metacheiromyidae</span> Extinct family of mammals

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<span class="mw-page-title-main">Epoicotheriinae</span> Extinct subfamily of mammals

Epoicotheriinae is an extinct paraphyletic subfamily of insectivorous placental mammals within extinct paraphyletic family Epoicotheriidae in extinct order Palaeanodonta, that lived in North America and Europe from the early Eocene to early Oligocene. Epoicotheriins were fossorial mammals. Late Eocene/early Oligocene genera were highly specialized animals that were convergent with the talpids, golden moles and marsupial mole in the structure of their skulls and forelimbs, and would have had a similar lifestyle as subterranean burrowers.

Cryptomanis is an extinct genus of pangolin from extinct family Patriomanidae. The genus is only known from the holotype specimen from middle Eocene deposits from Inner Mongolia, China. The holotype, AMNH 26140, was for years labeled as an unnamed pangolin in the fossil collection for decades. The remains comprise of an incomplete postcranial specimen, with nearly complete hind limbs, an incomplete pelvis, a complete lumbar series from an incomplete vertebral column, numerous fragmentary remains of rib and sternal bones, a fragmentary scapula, and partially preserved forelimbs. Based on the femural length Cryptomanis was comparable in size to the modern Sunda pangolin.

References

  1. 1 2 3 E. H. Colbert (1942). Edentate from the Oligocene of Wyoming. Academy of Natural Sciences, No. 109. ISBN   978-1-60483-109-2.{{cite book}}: |journal= ignored (help)
  2. Rose, Kenneth D.; Emry, Robert J. (1983). "Extraordinary fossorial adaptations in the oligocene palaeanodonts Epoicotherium and Xenocranium (Mammalia)". Journal of Morphology. 175 (1): 33–56. doi:10.1002/jmor.1051750105. ISSN   1097-4687. PMID   30053775. S2CID   51727274.
  3. 1 2 Postilla. Peabody Museum of Natural History. 1894.
  4. Scott, William Berryman (1913). A History of Land Mammals in the Western Hemisphere. MacMillan.
  5. Kenneth D. Rose (2008). "Palaeanodonta and Pholidota". In Janis, Christine M; Gunnell, Gregg F; Uhen, Mark D (eds.). 9 - Palaeanodonta and Pholidota. pp. 135–146. doi:10.1017/CBO9780511541438.010. ISBN   9780511541438.
  6. Gaudin, Timothy (2009). "The Phylogeny of Living and Extinct Pangolins (Mammalia, Pholidota) and Associated Taxa: A Morphology Based Analysis" (PDF). Journal of Mammalian Evolution. Heidelberg, Germany: Springer Science+Business Media. 16 (4): 235–305. doi:10.1007/s10914-009-9119-9. S2CID   1773698.
  7. Kondrashov, Peter; Agadjanian, Alexandre K. (2012). "A nearly complete skeleton of Ernanodon (Mammalia, Palaeanodonta) from Mongolia: morphofunctional analysis". Journal of Vertebrate Paleontology. 32 (5): 983–1001. doi:10.1080/02724634.2012.694319. ISSN   0272-4634. S2CID   86059673.