Temporal range: 58.7–40.4 Ma
Didymictis is an extinct genus of carnivorous mammals known from the late Paleocene and early Eocene (Tiffanian-Gardnerbuttean NALMA) of North America. This genus in the family Viverravidae contains five species.
Didymictis is the only viverravid for which there are considerable postcranial remains. The genus was primarily terrestrial but at least partly cursorial, similar to a civet.
Didymictis has an elongated and relatively large skull with small and low braincase and a long and narrow basicranial region. The occipital and saggital crests are very high. The limbs are of moderate length with subdigitigrade and five-toed feet. The dentition (184.108.40.206) contrast those of miacids 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.
Comparing Didymictis to Vulpavus, a much smaller and more agile viverravid, Heinrich & Rose 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.
D. proteus is known from the late Paleocene and earliest Eocene of Wyoming and the only species present in the Tiffanian and Clarkforkian stages (60–55 Ma). It is slightly larger than D. leptornylus and slightly smaller than D. protenus. Simpson 1937 named a new subspecies, Didymictis protenus proteus, which Polly 1997 reranked as the species D. proteus. Dorr 1952 described Didymictis dellensis which Gingerich & Winkler 1985 included in Protictis dellensis. Polly 1997 finally included these species in D. proteus.
D. protenus is known from the earliest through late Wasatchian (early Eocene) of western North America. 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. Cope later created a new genus and renamed his species Didymictis protenus.
D. vancleveae is known from a fragmented jaw with several teeth (Colorado) described by Robinson 1966 and another tooth (Wyoming) tentatively assigned to this species. Robinson described D. vancleveae as larger than D. altidens and probably the youngest Didymicits. He assumed that the genus grew larger as it evolved.
- "Didymictis". Fossilworks. Retrieved September 2014. Check date values in:
- The Gardnerbuttean is a transitional stage between the Wasatchian and Bridgerian Land Mammal Ages. (Gunnell 2001, p. 407)
- Polly 1997, p. 34
- Heinrich & Houde 2006, Introduction, p. 422
- Matthew 1937, Diagnosis, p. 101
- Heinrich & Rose 1997, Summary, pp. 300–301
- Polly 1997, pp. 34–35
- Gingerich & Winkler 1985, p. 117
- Polly 1997, pp. 41
- Cope 1874, pp. 126–127
- Cope 1875, p. 11
- Gunnell et al. 1992, p. 276
- Robinson 1966, pp. 48–49
- Cope, E. 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. Retrieved September 2014. Check date values in:
- Cope, E. 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. Retrieved September 2014. Check date values in:
- Cope, E. D. (1880a). "The Bad Lands of the Wind River and their Fauna". The American Naturalist. 14 (10): 745–748. doi:10.1086/272667. JSTOR 2449738.
- Cope, E. D. (1880b). "General Notes: The Northern Wasatach Fauna". American Naturalist. 14: 908. doi:10.1086/272689. Retrieved September 2014. Check date values in:
- Dorr, J. A. (1952). "Early Cenozoic stratigraphy and vertebrate paleontology of the Hoback Basin, Wyoming". Bulletin of the Geological Society of America. 63: 59–94. doi:10.1130/0016-7606(1952)63[59:ECSAVP]2.0.CO;2.
- Flynn, J. J. (1998). "Early Cenozoic Carnivora ("Miacoidea")". In Janis, C. M.; Scott, K. M.; Jacobs, L. L. Evolution of Tertiary Mammals of North America. Volume 1: Terrestrial Carnivores, Ungulates, and Ungulatelike Mammals. Cambridge: Cambridge University Press. pp. 110–123. ISBN 0-521-35519-2. Retrieved September 2014. Check date values in:
- Gingerich, P. D.; Winkler, D. A. (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. Retrieved September 2014. Lay summary (September 2014). Check date values in:
- Gunnell, G. F. (2001). Eocene Biodiversity: Unusual Occurrences and Rarely Sampled Habitats. Springer. ISBN 9780306465284. Retrieved September 2014. Check date values in:
- 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. Retrieved September 2014. Check date values in:
- 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. Retrieved September 2014. Check date values in:
- 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. Retrieved September 2014. Check date values in:
- Matthew, W. D. (1937). "Paleocene faunas of the San Juan basin, New Mexico". Transactions of the American Philosophical Society, new ser. 30 (1). ISBN 1-4223-7738-5. OCLC 4673155.
- Polly, P. D. (1997). "Ancestry and species definition in paleontology: a stratocladistic analysis of Paleocene-Eocene Viverravidae (Mammalia, Carnivora) from Wyoming" (PDF). Contributions from the Museum of Paleontology. 30 (1): 1–53. Retrieved September 2014. Lay summary (September 2014). Check date values in:
- Robinson, P. "Fossil Mammalia of Huerfano Formation, Eocene, of Colorado". Peabody Museum of natural History. 21: 48–49. Retrieved September 2014. Check date values in:
|access-date=(help) (Plate VII)
- Simpson, G. G. (1937). "Notes on the Clark Fork, Upper Paleocene, fauna". American Museum Novitates. 954. Retrieved September 2014. Check date values in: