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Creodonta
Fossil range: Late Paleocene to Late Miocene, 63.3–11.1 Ma
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Sarkastodon
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Eutheria
Superorder: Laurasiatheria
Order: Creodonta
(Cope, 1875)
Families

Hyaenodontidae
Oxyaenidae

The creodonts are an extinct order of mammals that lived from the Paleocene to the Miocene epochs. They shared a common ancestor with the Carnivora.

Creodonts were an important group of carnivorous mammals from 55 to 35 million years ago in the ecosystems of Africa, Eurasia and North America. In Oligocene Africa, they were the dominant predatory group. They competed with the Mesonychids and the Entelodonts and ultimately outlasted them by the start of the Oligocene and by the middle of the Miocene respectively, but lost ground to the carnivorans. The last genus went extinct 8 MYA, and carnivorans now occupy their ecological niches.

Contents

Evolution and taxonomy

Creodonts were traditionally considered ancestors to Carnivora, but are now considered to have shared a common ancestor further back - possibly a Cimolesta such as Cimolestes. They share with the Carnivora the carnassial shear, a modification of teeth that evolved to slice meat in a manner like scissors and gave both orders the tools to dominate the niche. Some researchers argue that the creodonts represent a group of mammals of diverse biological ancestry that resemble one another via convergent evolution, rather than being the descendants of a single common ancestor. Their origins lie at least as far back as the late Cretaceous, though they did not radiate much until the Cenozoic.[1] Creodonts were the dominant carnivorous mammals from 55 to 35 MYA, peaking in diversity and prevalence during the Eocene.[1] By the mid Oligocene, Creodonts supplanted both the Mesonychids, and giant flightless predatory birds entirely in North America, Eurasia and Africa, and in turn, competed with their own relatives, the Carnivorans. The last genus, Dissopsalis, went extinct about eight million years ago.

Habitat

The creodonts ranged across North America, Eurasia and Africa, in forms that resemble those of some modern carnivores. Amongst their number was Megistotherium, which may have been the largest mammalian land predator of all time, the size of a bison and with a skull twice as big as a tiger's. Megistotherium may have rivaled Andrewsarchus mongoliensis in size. Their dominance over the early Carnivora, known as miacids, began to wane after 35 MYA. The creodonts survived until 8 million years ago; the last form, Dissopsalis, died out in Pakistan. Bears, cats, mustelids, hyenas, canids such as wolves and other Carnivora now occupy the former creodont niches.

Reasons for extinction

Skull of Hyaenodon

It is not known exactly why the creodonts were replaced by Carnivora. It may be because of their smaller brains and their locomotion, which was somewhat less energy-efficient (especially while running) and mostly plantigrade.[2] These subtle disadvantages may have been important over millions of years. The creodont lumbosacral spine was not arranged as efficiently for running as in Carnivora. The arrangement of the teeth was also somewhat different. In the miacids (and so in the modern Carnivora), the last upper premolar and the first lower molar are the carnassials, allowing grinding teeth to be retained behind for feeding on non-meat foods (the Canidae are the closest modern analog to miacid dentition). In creodonts, the carnassials were further back - either first upper and second lower molars, or second upper and third lower molars. This committed them to eating meat almost exclusively.

In the most strictly carnivorous family of modern Carnivora, the Felidae, the second and third molars have disappeared completely, and the first upper molars behind the carnassials have become vestigial. Modern cats thus eat plant food only incidentally.

References

  • The Velvet Claw: A Natural History of the Carnivores, David Macdonald, BBC Books, ISBN 0-563-20844-9
  • David Lambert and the Diagram Group. The Field Guide to Prehistoric Life. New York: Facts on File Publications, 1985. ISBN 0-8160-1125-7

Footnotes

  1. ^ a b Lambert, 162
  2. ^ "The Elements of Geology". Globusz. http://www.globusz.com/ebooks/Geology/00000034.htm. Retrieved March 11 2008.  
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1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

'CREODONTA, a group of primitive early Tertiary Carnivora, characterized by their small brains, the non-union in most cases of the scaphoid and lunar bones of the carpus, and the general absence of a distinct pair of "sectorial" teeth '(see Carnivora). In many respects the Lower Eocene creodonts come very close to the primitive ungulates, or Condylarthra (see Phenacodus), from which, however, they are distinguished by the approximation in the form of the skull to the carnivorous type, the more trenchant teeth (at least in most cases) and the more claw-like character of the terminal joints of the toes. The general character of the dentition in the more typical forms,such as Hyaenodon (see fig.), recalls that of the carnivorous marsupials, this being especially the case with the Patagonian species, which have been Dentition of Hyaenodon leptorhynchus, from the Lower Oligocene of France. The last upper molar is concealed by the penultimate tooth.

separated as a distinct group under the name of Sparassodonta. The skull, however, is not of the marsupial type, and in the European forms at any rate there is a complete replacement of the milk-molars by pre-molars, while the minute structure of the enamel of the teeth is of the carnivorous as distinct from the marsupial type. The head is large in proportion to the body, the lumbar region is unusually rigid, owing to the complexity of the articulations, and the tail and hind-limbs are relatively long and powerful. In life the tail probably passed almost imperceptibly into the body, as in the Tasmanian thylacine.

That the Creodonta are the ancestors of the modern Carnivora is now generally admitted. They are apparently the most generalized and primitive of all (placental?) mammals, and probably the direct descendants of the mammal-like anomodont or theromorphous reptiles of the Triassic epoch; the evolution from that group having perhaps taken place in Africa or in the lost area connecting that continent with India. The relationship of the creodonts to the carnivorous marsupials is not yet determined, but it seems scarcely probable that the remarkable resemblance existing between the teeth of the two groups can be solely due to parallelism; and it has been suggested by Dr L. Wortman that both creodonts and marsupials are descended from a common non-placental stock. In other words, the latter are a side-branch from the anomodont-creodont line of descent. Dr C. W. Andrews has pointed out that certain of the Egyptian creodonts appear to have been aquatic or subaquatic in their habits; and it is possible that from such types are derived the true seals, or Phocidae. With the exception of Australasia, and perhaps South Africa, creodonts (on the supposition that the Patagonian forms are rightly included) appear to have had a nearly world-wide distribution. In Europe and North America they date from the Lowest Eocene and lived till the early Oligocene, while in India they apparently survived till a much later epoch. Some of the Oligocene forms, alike as regards dentition, the union of the scaphoid and lunar of the carpus, and the complexity of the brain, approximated to modern Carnivora.

As regards classification Mr W. D. Matthew includes in the typical family Hyaenodontidae not only the widely spread genera Hyaenodon and Pterodon, but likewise Sinopa (Stypolophus), Cynohyaenodon and Proviverra; but Viverravus (Didymictis) and Vulpavus (Miacis) are assigned to a separate family (Viverravidae). It is these latter forms which come nearest to modern Carnivora, most of them being of Oligocene age. The American and European Oxyaena apparently represents a family by itself, as does the American Oxyclaena; and Palaeonictis and Patriofelis are assigned to yet another family; while the North American Lower Eocene and Eocene Arctocyon typifies a family characterized by the somewhat bear-like type of dentition. Mesonyx is also a very distinct type, from the North American Eocene and Oligocene. Some of the species of Patriofelis and Hyaenodon attained the size of a tiger, although with long civet-like skulls. In the earlier forms the claws often retained somewhat of a hooflike character.

The South American Borhyaenidae include Borhyaena, Prothylacinus, Amphiproviverra, and allied forms from the Santa Cruz beds of Patagonia, and have been referred to a distinct group, the Sparassodonta, mainly on account of the alleged replacement of some only of the milk-molars by premolars. By their first describer, Dr F. Ameghino, they were regarded as nearly related to the marsupials, to which group they were definitely referred in 1905 by Mr W. J. Sinclair, by whom they are considered near akin to Thylacinus, but this view seems to be disproved by the investigations of Mr C. S. Tomes into the structure of the dental enamel.

It should be added that Dr J. L. Wortman transfers Viverravus and its allies, together with Palaeonictis, to the true Carnivora, the latter genus being regarded as the ancestral type of the sabretoothed cats (see Machaerodus).

Authorities.-J. L. Wortman, "Eocene Mammalia in the Peabody Museum, pt. i. Carnivora," Amer. J. Sci. vols. xi.-xiv. (1901-1902); W. D. Matthew, "Additional Observations on the Creodonta," Bull. Amer. Illus. vol. xiv. p. i. (1901); C. W. Andrews, Descriptive Catalogue of the Tertiary Vertebrata of the Fayum, British Museum (1906); W. J. Sinclair, "The Marsupial Fauna of the Santa Cruz Beds," Proc. Amer. Phil. Soc. vol. xlix. p. 73 (1905).

(R. L.*)


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Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Translingual

Proper noun

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Wikipedia

Creodonta

  1. a taxonomic order, within superorder Laurasiatheria - several extinct mammals that were dominant in the Cenozoic era
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Wikispecies

See also

  • Oxyaenidae
  • Hyaenodontidae

Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Superordo: Laurasiatheria
Ordo: †Creodonta
Familiae: Oxyaenidae - Hyaenodontidae

Name

Creodonta (Cope, 1875)

Vernacular names

日本語: 肉歯目
中文: 肉齒目
Wikimedia Commons For more multimedia, look at Category:Creodonta on Wikimedia Commons.

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