The Searching Wolf



Chronology of Wolf Evolution

* MYA - Millions of Years Ago
** Geological Period or Epoch
*** Reference Numbers in Parentheses

MYA * Period or Epoch ** Event(s)
300 Late Carboniferous Appearance of the mammal-like reptiles (subclass Synapsida). (9)(11) ***
230 Middle Triassic Mammals evolve from the therapsids, a group of mammal-like reptiles (9)(11)
64 - 210 Late Triassic - Late Cretaceous Dinosaurs dominate. Generally, mammals are small, usually mouse-sized, and nocturnal. (9)(11)
64 - 65 Late Cretaceous Dinosaurs and many other organisms become extinct. Most of the mammals that survive are insectivores or omnivores. (9)(11)

Mammals begin to radiate into the ecological niches vacated by the dinosaurs. (9)(11)

Appearance of the insectivore (insect-eating) genus Cimolestes, considered a basal carnivore group. The largest member might be ferret-sized. (2)(11)

63 Early Paleocene The carnivorous group of mammals, order Creodontia, appears. Creodonts are slow, clumsy, and inefficient. (9) They become extinct in the early Pliocene. (11)

Creodonts are mostly replaced by the Carnivora, the second and more recent order of mammalian carnivores. The two orders are distinctly different lines of carnivores. They are distinquished by differences in their shearing teeth, bones of the carpus, and auditory bullae. * (7)(9)(11)

* Recent carnivores, which are derived only from the order Carnivora, have the following features, among others: (11)

  • The shearing teeth or carnassials are the upper fourth premolar and the lower first molar
  • In the carpus, fused scaphoid and lunar bones, and no centrale
  • Ossified auditory bulla (bony covering of the middle ear cavity)
  • Large brains
60 Middle Paleocene Miacidae, the basal family of the order Carnivora, appears. Miacids are small: the average one is about the size of a ferret. They are arboreal with long, lithe bodies, and long tails. They also possess Carnivora type carnassials but lack fully ossified auditory bullae. (10)(11) They resemble Cimolestes, an observation that adds weight to the suggestion that the order Carnivora evolved from insectivores. (11)

The miacids are divided into two groups: the miacines with a full complement of molars and the viverravines with a reduced number of molars and more specialized carnnassials. (10)

48 Middle Eocene

The two main branches of the Order Carnivora arise from the miacids: Caniformia (dogs, raccoons, bears, sea lions, seals, walruses, and weasels) and Feliformia (cats, hyenas, civets, genets, and mongooses). (7)(11)

Dentally, the miacines resemble the Caniformians while the viverravines resemble the Feliformians. However, this may not mean evolutionary affinities. (10)

The Caniformia have an auditory bulla that is single-chambered (bears, weasels, raccoons, seals, etc.) or partially divided (dogs). The Feliformia have a double-chambered auditory bulla. (10)

37 Early Oligocene The canid branch of the Caniformia begins. This is the first split within the Caniformia. (7)

In North America, Hesperocyon appears. It is the first canid genus and the basis of the hesperocyonine radiation, the first of three radiations of canids. These canids are small kit fox-sized animals with supple, muscular bodies, long tails, padded feet, and relatively short muzzles. They walk on their toes (digitigrade) like modern canids and are good climbers. Their limbs and feet probably make them better fitted for running than the miacids. They have carnassials adapted for shearing and ossified auditory bullae. (2)(5)(10)

Canid evolutionary trends:

  • Longer legs
  • 5 toes to 4 toes with a vestigial 5th toe on the front feet
  • Shorter tail
29 Late Oligocene The hesperocyonine radiation takes place in North America. It includes frugivorous, bone-crushing hyena-like, and coyote-sized canids. A bear dog (amphicyonid)* fills the large bone-crushing hunting dog niche. The hesperocyonine canids never go to the Old World. (2)

* The bear dogs originate in Eurasia.

23 Early Miocene Hesperocyonine dogs become extinct except for the (Nothocyon) and (Leptocyon) branches, that lead to the borophagine and canine radiations, the second and third canid radiations, respectively. (2)(10)
16 - 23 Early Miocene - Middle Miocene In North America, Tomarctus, derived from the Nothocyon line, gives rise to the borophagine radiation. The canids of this radiation are short-faced, heavy-jawed, and often massive in size. They are contemporary with a variety of bear dogs that fill many of the canid niches. A giant mustelid* genus may fill a bone-crushing niche. The borophagine canids never go to the Old World. (2)(10)

* Mustelids are the weasels, polecats, mink, etc.

With the extinction of the bear dogs and giant mustelids, a further radiation of the Tomarctus line of dogs occurs filling frugivorous, bone-crushing hyena-like, and large bone-crushing niches. (2)

Although Canis-like, based on skull and teeth features, the Tomarctus line doesn't appear to lead to the modern dogs, the canines. (5)(10)

9 - 10 Late Miocene The third canid radiation begins. This is the canine radiation based on the small fox Leptocyon. The decline of the borophagines possibly opens the way for this radiation which begins in North America with the appearance of three genera: Canis, Urocyon, and Vulpes. (2)(10)

It is from the canine radiation that all living dogs are derived. That radiation began in the southwest United States, the birthplace of modern dogs.

The success of the canines is the dvelopment of lower carnassials that are capable of both mastication and shearing. (10)

8 Late Miocene Canines spread to Eurasia. Dogs, much like the small coyote Canis davisii cross Beringia and enter Eurasia. The migration results in the major portion of the canine radiation which probably occurs in Asia with the appearance of wolves, jackals, hunting dogs, foxes, and raccoon dogs. (2)(10)
6 Late Miocene A wolf-like Canis appears in western Europe. (10)
4 - 5 Pliocene Canines spread to Africa (Early Pliocene) and South America (Late Pliocene). (1)

In North America, Canis lepophagus appears. This dog is small and varied. Some individuals are coyote-like while others have wolf-like characteristics. In the late Pliocene, the coyote (Canis latrans) probably descended from Canis lepophagus. (4)

1.5 - 1.8 Early Pleistocene Several kinds of wolves are found in Europe. (2)

Extensive development and diversification of the North American wolf line takes place. Canis edwardii is the first North American canine clearly identifiable as a wolf. (6)

A red wolf (Canis rufus) -like canine appears, possibly a direct descendent of Canis edwardii. (4)(6)

During the Pleistocene, the glaciations allow complex continental intermigrations of canines and other mammals due to the periodic emergence of the Bering Strait. (2)

0.8 Mid-Pleistocene In North America, Canis ambrusteri, a large wolf, appears and probably is found all over the continent. It disappears, perhaps going to South America where it becomes the ancestor of the dire wolf, Canis dirus, a large, bone-crushing hunting dog. However, the dire wolf may have arose from small South American wolves. (3)(6)
0.3 Late Pleistocene The gray wolf (Canis lupus) fully develops in northern Eurasia and spreads all over Europe and northern Asia. Eventually, it crosses into North America via the Bering Strait land bridges. (3)
0.1 Late Pleistocene Dire wolves appear in North America. They have huge heads and tremendous teeth. Some are the largest members of the dog family ever to exist. Wherever dire wolves and gray wolves occur together, gray wolves tend to be smaller. The dire wolf ranges from coast to coast in North America and from southern Canada to South America. The dire wolf becomes extinct about 8,000 years ago. (3)(6)
0.0025 - 0.0125 Late Pleistocene - Holocene According to DNA analysis research, the red wolf appear as a result of hybridization of gray wolves and coyotes (Canis latrans) that occurs "during the past 12,500 years, and probably during the past 2,500 years." (8)

However, other DNA research gives a different story: DNA from eastern Canadian wolves, gray wolves (Canis lupus) from other areas of North America, coyotes (Canis latrans), and red wolves (Canis rufus) were compared. The results indicate that (1) the eastern Canadian wolf is not a gray wolf, (2) the eastern Canadian wolf and the red wolf are very closely related, and (3) the eastern North American wolves are more closely related to the coyote than to the gray wolf. Based on these findings, the authors suggest the following evolutionary model: There was a branching 1 - 2 million years ago from a common ancestor of gray wolves, the eastern North American wolves, and coyote. One of the branches migrated to Eurasia and there gave rise to the gray wolf. The other branch remained in North America and 150,000 - 300,000 years ago branched into the ancestor of the eastern North American wolves and the coyote. (12)

(1) Hunt, R.M., Jr. 1996. Biogeography of the Order Carnivora. Pages 485 - 541 in J.L. Gittleman, editor. Carnivore Behavior, Ecology, and Evolution, Vol. 2. Comstock Publishing Associates: Ithaca.
(2) Martin, L.D. 1989. Fossil history of the terrestrial carnivora. Pages 536 - 568 in J.L. Gittleman, editor. Carnivore Behavior, Ecology, and Evolution, Vol. 1. Comstock Publishing Associates: Ithaca.
(3) Nowak, R. 1992. Wolves: The great travelers of evolution. International Wolf 2(4):3 - 7.
(4) Nowak, R.M. 1979. North American Quaternary Canis. Monograph of the Museum of Natural History, University of Kansas 6:1 - 154.
(5) Olsen, S.J. 1985. Origins of the Domestic Dog: The Fossil Record. The University of Arizona Press: Tucson.
(6) Paradiso, J.L. and R.M. Nowak. 1982. Wolves. Pages 460 - 474 in J.A. Chapman and G.A. Feldhamer, editors. Wild Mammals of North America: Biology, Management, and Economics. The Johns Hopkins University Press: Baltimore.
(7) Prothero, D.R. 1994. Mammalian Evolution. Pages 238 - 270 in R.S. Spencer, editor. Major Features of Vertebrate Evolution, Short Courses in Paleontology Number 7, convened by D.R. Prothero and R.M. Schoch, A publication of The Paleontological Society. UTK Publication: Knoxville.
(8) Reich, D.E., R.K. Wayne, and D.B. Goldstein. 1999. Genetic evidence for a recent origin by hybridization of red wolves. Molecular Ecology 8:139 - 144.
(9) Romer, A.S. and T.S. Parsons. 1985. The Vertebrate Body. Saunders College Publishing: Philadelphia.
(10) Tedford, R.H. 1978. History of dogs and cats: A view from the fossil record. Pages 1 - 10 in Nutrition and Management of Dogs and Cats. Ralston Purina Co.: St. Louis.
(11) Vaughan, T.A. 1985. Mammalogy. Saunders College Publishing: Fort Worth.
(12) Wilson, P.J., S. Grewal, I.D. Lawford, J.N.M. Heal, A.G. Granacki, D. Pennock, J.B. Theberge, M.T. Theberge, D.R. Voigt, W. Waddell, R.E.Chambers, P.C. Paquet, G. Goulet, D. Cluff, and B.N. White. 2000. DNA profiles of the eastern Canadian wolf and the red wolf provide evidence for a common evolutionary history independent of the gray wolf. Canadian Journal of Zoology 78:2156 - 2166.