Didymictis
Temporal range: late Paleocene and middle Eocene
Skull of Didymictis protenus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superfamily: †Viverravoidea
Family: †Viverravidae
Subfamily: †Didymictinae
Genus: †Didymictis
Cope, 1875[1]
Type species
†Didymictis protenus
Cope, 1874
Species[2]
[see classification]
Synonyms
synonyms of species:
  • D. altidens:
    • Viverravus altidens (Cope, 1880)
  • D. dellensis:
    • Protictis dellensis (Dorr, 1952)
  • D. leptomylus:
    • Viverravus leptomylus (Cope, 1880)
  • D. protenus:
    • Didymictis curtidens (Cope, 1882)
    • Limnocyon protenus (Cope, 1874)
    • Viverravus curtidens (Cope, 1882)
    • Viverravus protenus
  • D. proteus:
    • Didymictis protenus proteus (Simpson, 1937)[3]

Didymictis ("double weasel") is an extinct genus of placental mammals from extinct subfamily Didymictinae within extinct family Viverravidae, that lived in North America and Europe from the late Paleocene to middle Eocene.[4][5][6][7]

Description

Didymictis is the only viverravid genus for which there are considerable postcranial remains. The genus was primarily terrestrial but at least partly cursorial, similar to a civets.[8]

Didymictis has an elongated and relatively large skull with small and low braincase and a long and narrow basicranial region. The occipital and sagittal crests are very high. The limbs are of moderate length with subdigitigrade and five-toed feet. The dentition (3.1.4.23.1.4.2) contrast those of basal carnivoraforms by the sharp differentiation between sectorial and tubercular dentition, the loss of the last molar and an elongated second molar, similar to the dentition in bears and raccoons.[9]

Comparing Didymictis to Vulpavus, a much smaller and more agile carnivoraform, Heinrich and Rose in 1997 noted that Didymictis' limbs, especially the hindlimb, are similar to those in extant carnivornas adapted for speed, and the forelimbs to some extent are specialized to digging. The authors concluded that Didymictis was a relatively specialized terrestrial carnivore capable of hunting with speed or pursuing by digging.[10]

Classification and phylogeny

History of species and classification

D. protenus is known from the earliest through late Wasatchian (early Eocene) of western North America.[11] Cope assigned his specimen, "one entire and a portion of the other mandibular ramus, with teeth well preserved", to the creodont genus Limnocyon and named his new species L. protenus.[12] Cope later created a new genus and renamed his species Didymictis protenus.[1]

D. proteus is known from the late Paleocene and earliest Eocene of Wyoming and the only species present in the Tiffanian and Clarkforkian stages. It is slightly larger than D. leptornylus and slightly smaller than D. protenus.[11] Simpson in 1937 named a new subspecies, Didymictis protenus proteus,[3] which Polly in 1997 reranked as the species D. proteus.[11] Dorr in 1952 described Didymictis dellensis,[13] which Gingerich and Winkler in 1985 included in Protictis dellensis.[14] Polly in 1997 finally included these species in D. proteus.[11]

D. leptomylus is known from the early Wasatchian of western North America, but by far fewer specimens than D. proteus.[11]

D. vancleveae is known from a fragmented jaw with several teeth (Colorado) described by Robinson in 1966 and another tooth (Wyoming) tentatively assigned to this species.[15] Robinson described D. vancleveae as larger than D. altidens and probably the youngest Didymicits. He assumed that the genus grew larger as it evolved.[16]

Taxonomy

Genus: †Didymictis (Cope, 1875)
Species:Distribution of the species and type locality:Age:
†D. altidens (Cope, 1880)[17]  USA (Colorado and Wyoming) 54,9 - 46,2 Ma
†D. dellensis (Dorr, 1952)[13]  Canada (Saskatchewan)
 USA (Wyoming)[18]		 60,9 - 54,9 Ma
†D. leptomylus (Cope, 1880)[19]  USA (Colorado and Wyoming[20]) 54,9 - 50,5 Ma
†D. protenus (Cope, 1874)[12]  USA (Colorado,New Mexico and Wyoming) 56,2 - 50,5 Ma
†D. proteus (Polly, 1997)[11]  Canada (Alberta)
 USA (Colorado, South Carolina and Wyoming)		 60,9 - 50,5 Ma
†D. vancleveae (Robinson, 1966)[16]  USA (Colorado and Wyoming[15]) 50,5 - 46,2 Ma
†D. sp. [Erquelinnes, Hainaut, Belgium] (Dollo, 1909)[21]  Belgium (Hainaut Province) 56,0 - 55,2 Ma

References

  1. 1 2 Cope, Edward D. (1875). "Systematic Catalogue of Vertebrata of the Eocene of New Mexico: Collected in 1874. Report to the Engineer Department". Washington D.C.: United States Army, US Government Printing Office: 5–37. {{cite journal}}: Cite journal requires |journal= (help)
  2. ↑ "Didymictis". Fossilworks.
  3. 1 2 Simpson, George Gaylord (1937). "Notes on the Clark Fork, Upper Paleocene, fauna". American Museum Novitates (954). hdl:2246/2190.
  4. ↑ Cope, E. D. (December 1880). "General Notes: The Northern Wasatach Fauna". American Naturalist. 14 (12): 908. doi:10.1086/272689.
  5. ↑ McKenna, Malcolm C.; Bell, Susan K. (1997). Classification of Mammals Above the Species Level. New York: Columbia University Press. ISBN 978-0-231-11012-9. Retrieved 16 March 2015.
  6. ↑ J. J. Flynn (1998.) "Early Cenozoic Carnivora ("Miacoidea")." In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.) "Evolution of Tertiary Mammals of North America. Volume 1: Terrestrial Carnivores, Ungulates, and Ungulatelike Mammals." Cambridge University Press, Cambridge. ISBN 0-521-35519-2
  7. ↑ Gunnell, G. F. (2001). Eocene Biodiversity: Unusual Occurrences and Rarely Sampled Habitats. Springer. ISBN 9780306465284.
  8. ↑ Heinrich, R. E.; Houde, P. (2006). "Postcranial anatomy of Viverravus (Mammalia, Carnivora) and implications for substrate use in basal Carnivora". Journal of Vertebrate Paleontology. 26 (2): 422–435. doi:10.1671/0272-4634(2006)26[422:paovmc]2.0.co;2. S2CID 40158814.
  9. ↑ Matthew, W. D. (1937). "Paleocene faunas of the San Juan basin, New Mexico". Transactions of the American Philosophical Society. New Series. 30 (1): 46–47. Bibcode:1937Natur.140...46C. doi:10.1038/140046a0. ISBN 1-4223-7738-5. OCLC 4673155. S2CID 42553547.
  10. ↑ Heinrich, R. E.; Rose, K. D. (1997). "Postcranial morphology and locomotor behaviour of two early Eocene miacoid carnivorans, Vulpavus and Didymictis" (PDF). Palaeontology. 40: 279–306. Archived from the original (PDF) on 2014-09-13.
  11. 1 2 3 4 5 6 P. D. Polly (1997) "Ancestry and Species Definition in Paleontology: A Stratocladistic Analysis of Paleocene-Eocene Viverravidae (Mammalia, Carnivora) from Wyoming." Contributions from the Museum of Paleontology, University of Michigan 30(1):1-53
  12. 1 2 Cope, Edward D. (1874). "Notes on the Eocene and Pliocene Lacustrine Formations of New Mexico, Including Descriptions of Certain New Species of Vertebrates". Annual Report of the Chief of Engineers for 1874. Appendix FF.
  13. 1 2 Dorr, J. A. (1952). "Early Cenozoic stratigraphy and vertebrate paleontology of the Hoback Basin, Wyoming". Bulletin of the Geological Society of America. 63 (1): 59–94. Bibcode:1952GSAB...63...59D. doi:10.1130/0016-7606(1952)63[59:ECSAVP]2.0.CO;2.
  14. ↑ P. D. Gingerich and D. A. Winkler (1985) "Systematics of Paleocene Viverravidae (Mammalia, Carnivora) in the Bighorn Basin and Clark's Fork Basin, Wyoming." Contributions from the Museum of Paleontology, University of Michigan 27(4):87-128
  15. 1 2 Gunnell, G. F.; Bartels, W. S.; Gingerich, P. D.; Torre, V. (1992). "Wapiti Valley Faunas: Early and Middle Eocene Fossil Vertebrates from the North Fork of the Shoshone River, Park Country, Wyoming". Contributions from the Museum of Paleontology, the University of Michigan. 28 (11): 247–287. hdl:2027.42/48547.
  16. 1 2 Robinson, P. (1966). "Fossil Mammalia of Huerfano Formation, Eocene, of Colorado". Bulletin of the Peabody Museum of Natural History. 21: 48–49.(Plate VII)
  17. ↑ Cope, Edward D. (1880). "The Bad Lands of the Wind River and their Fauna". The American Naturalist. 14 (10): 745–748. doi:10.1086/272667. JSTOR 2449738.
  18. ↑ R. Secord (2008.) "The Tiffanian Land-Mammal Age (middle and late Paleocene) in the northern Bighorn Basin, Wyoming." University of Michigan Papers on Paleontology 35:1-192
  19. ↑ Cope, Edward D. (1880). "General Notes: The Northern Wasatach Fauna". American Naturalist. 14: 908. doi:10.1086/272689.
  20. ↑ K. D. Rose, A. E. Chew, R. H. Dunn, M. J. Kraus, H. C. Fricke and S. P. Zack (2012.) "Earliest Eocene mammalian fauna from the Paleocene-Eocene Thermal Maximum at Sand Creek Divide, southern Bighorn Basin, Wyoming." University of Michigan Papers on Paleontology 36:1-122
  21. ↑ Lours Dollo (1909.) "The fossil vertebrates of Belgium" Annals of the New York Academy of Sciences, 19(1):99 - 119
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