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The correct spelling of the name is Prothylacynus, not Prothylacinus.
Fixed ambiguity regarding classification
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†[[Borhyaenidae]]<br/>
†[[Borhyaenidae]]<br/>
†[[Proborhyaenidae]]<br/>
†[[Proborhyaenidae]]<br/>
†[[Prothylacinidae]]<br/>
†[[Thylacosmilidae]]
†[[Thylacosmilidae]]
}}
}}
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==Classification==
==Classification==
The taxonomic classification below follows the latest review of the group, that of Forasiepi, 2009.<ref name="academia" /> Although ''Mayulestes'' was originally described as a sparassodont, later phylogenetic analyses have shown that it most likely does not belong to this group.<ref>{{cite journal| title=''Mayulestes ferox'', a borhyaenoid (Metatheria, Mammalia) from the early Paleocene of Bolivia. Phylogenetic and palaeobiologic implications|first=Christian|last=de Muizon|journal=[[Geodiversitas]]|year=1998|volume=20|pages=19-142}}</ref><ref name="academia" /> Similarly, while basal borhyaenoids such as ''Lycopsis'' and ''Prothylacynus'' were once thought to belong to a distinct family (Prothylacynidae), phylogenetic analyses have found that these animals do not represent a [[monophyletic]] group.<ref>{{cite journal| title=A new species of Hathliacynidae (Metatheria, Sparassodonta) from the middle Miocene of Quebrada Honda, Bolivia|first=Analia M.|last=Forasiepi|journal=[[Journal of Vertebrate Paleontology]]|year=2006|volume=26|issue=3|pages=670-684}}</ref><ref name="academia" />
The taxonomic classification below follows the latest review of the group, that of Forasiepi, 2009 (note the exclusion of ''[[Mayulestes]]'' and that the family Prothylacynidae{{clarify|date=December 2013}} is considered here as a [[paraphyletic]] assemblage of basal borhyaenoids)<ref name="academia" />


* '''Order Sparassodonta'''
* '''Order Sparassodonta'''

Revision as of 22:12, 7 December 2013

Sparassodonta
Temporal range: Paleocene-Pliocene
Thylacosmilus
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Infraclass:
Metatheria
Order:
†Sparassodonta

Ameghino, 1894
Families

†Hathliacynidae
†Borhyaenidae
†Proborhyaenidae
†Thylacosmilidae

Sparassodonta is an extinct order of carnivorous metatherian mammals native to South America. They were once considered to be true marsupials, but are now thought to be a sister taxon to them.[1][unreliable source?] A number of these mammalian predators closely resemble placental predators that evolved separately on other continents, and are cited frequently as examples of convergent evolution. They were first described by Florentino Ameghino, from fossils found in the Santa Cruz beds of Patagonia. Sparassodonts were present throughout South America's long period of "splendid isolation" during the Cenozoic; during this time they shared the niches for large warm-blooded predators with the flightless terror birds. Previously, it was thought that these mammals died out in the face of competition from "more competitive" placental carnivorans during the Pliocene Great American Interchange, but more recent research has showed that sparassodonts died out long before eutherian carnivores arrived in South America (aside from procyonids).[2]

Features

Although members of the order Sparassodonta showed many similarities with placental carnivores, they were not closely related and are a very good example of convergent evolution. For example, sparassodonts' molars were very similar to the sharp teeth of placental carnivores. The canines were also lengthened, and in some cases resemble those of saber-toothed cats. Sparassodonts spanned a wide range of body sizes, from 2.2 pound (1 kg) weasel or civet-like forms to Thylacosmilus, which was the size of a leopard.[2][3]

The early history of the Sparassodonta is poorly known, as most Paleocene and Eocene members of this group are only known from isolated teeth and fragmentary jaws. However, one species, the middle Eocene Callistoe vincei, is known from a nearly complete, articulated skeleton.[4] As Callistoe belongs to one of the most specialized groups of sparassodonts, this indicates that the other major groups (e.g. borhyaenids, hathliacynids, etc.) must have also arisen by this time. Originally, the early Paleocene metatherian Mayulestes was considered to be the earliest known member of the Sparassodonta, but phylogenetic analyses suggest that this species represents an independent radiation of carnivorous metatherians more closely related to Pucadelphys.[5] As of this writing[specify], the earliest known true sparassodonts are either Allqokirus australis, a species from the same site as Mayulestes which may also turn out to not be a sparassodont, and an isolated astragalus from the earliest Paleocene site of Punta Peligro, Argentina.[6] Marshall (1990) considered the Cretaceous stagodontids to also be a member of the Sparassodonta, but this was criticized by later authors.[7]

Sparassodonts can be divided into six major groups; basal sparassodonts (?earliest Paleocene-late Miocene), species that cannot be easily assigned to any of the other sparassodont groups and whose teeth often exhibit adaptations for omnivory; hathliacynids (late Oligocene-early Pliocene/latePliocene), which range from a marten to a thylacine in size, and have long, fox-like snouts and teeth strongly adapted for carnivory); basal borhyaenoids (middle Eocene-late Miocene), borhyaenoids that cannot be easily classified into the families Borhyaenidae, Thylacosmilidae, or Proborhyaenidae and vary in size and shape; borhyaenids (early-late Miocene), the sparassodont group most specialized for running, but not as much as living carnivorans or even thylacines; proborhyaenids (middle Eocene-late Oligocene), robust, wolverine-like forms with ever-growing upper and lower canines; and thylacosmilids (early Miocene-late Pliocene), another terrestrially specialized group with ever-growing saber-like upper canines.[5] With the exception of some basal sparassodonts, all members of this group were hypercarnivorous.[2] Based on studies of the postcranium, it appears as though most sparassodonts were scansorial, but terrestrial adaptations evolved in "Lycopsis" longirostrus, borhyaenids, proborhyaenids, and thylacosmilids.[8][9][10]

After the middle Miocene, sparassodonts began to slowly decline in diversity. Basal borhyaenoids are last known from the early late Miocene (Pseudolycopsis cabrerai and "Lycopsis" viverensis), and after this time were at least partially replaced by large-bodied basal sparassodonts such as Stylocynus. It has been suggested that this shift in dominance was due to the more omnivorous habits of basal sparassodonts, which may have been better able to exploit the more seasonal climates of South America during the late Neogene.[11] Borhyaenids are last known from the latest Miocene, though only fragmentary remains of this group are known from this period.[12] Later remains assigned to this group have since been reidentified as thylacosmilids or procyonids. By the Pliocene, only two families of sparassodonts remained in South America, the Hathliacynidae and the Thylacosmilidae. Pliocene hathliacynid remains are rare, and it is possible that these animals may have competed with the large carnivorous didelphids such as Lutreolina that appeared around this time.[13] Hathliacynids are last definitively known from the early Pliocene, though it has been suggested that the genus Borhyaenidium may have survived into the late Pliocene.[2] The thylacosmilids, on the other hand, were more successful and abundant, being some of the only large mammalian carnivores in South America during the Pliocene, and only died out at the end of the epoch. It is still not certain why the Sparassodonta declined in diversity and became extinct during the late Cenozoic, but it appears as though competition from eutherian carnivorans was not a factor, as the placental analogues of sparassodonts (dogs, weasels, and saber-toothed cats) did not enter South America until the middle Pleistocene, several million years after their sparassodont counterpart became extinct.[5][12][14]

Classification

The taxonomic classification below follows the latest review of the group, that of Forasiepi, 2009.[5] Although Mayulestes was originally described as a sparassodont, later phylogenetic analyses have shown that it most likely does not belong to this group.[15][5] Similarly, while basal borhyaenoids such as Lycopsis and Prothylacynus were once thought to belong to a distinct family (Prothylacynidae), phylogenetic analyses have found that these animals do not represent a monophyletic group.[16][5]

  • Order Sparassodonta

References

  1. ^ Naish, Darren (29 June 2008). "Invasion of the marsupial weasels, dogs, cats and bears... or is it?". Tetrapod Zoology. Retrieved 2008-12-07. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  2. ^ a b c d Prevosti, Francisco J. (2013). "The Evolution of the Cenozoic Terrestrial Mammalian Predator Guild in South America: Competition or Replacement?". Journal of Mammalian Evolution. 20: 3–21. doi:10.1007/s10914-011-9175-9. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  3. ^ Ercoli, Marcos D. (2011). "Estimacion de masa de las especies de Sparassodonta (Mammalia, Metatheria) de edad Santacrucense (Mioceno Temprano) a partir del tamano del centroide de los elementos apendiculares: inferencias paleoecologicas". Ameghiniana. 48: 462–479. doi:10.5710/amgh.v48i4.347. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  4. ^ Babot, María J. (2002). "Callistoe vincei a new Proborhyaenidae (Borhyaenoidea, Metatheria, Mammalia) from the Early Eocene of Argentina". Geobios. 35 (5): 615–629. doi:10.1016/S0016-6995(02)00073-6. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  5. ^ a b c d e f Forasiepi, Analía M. (2009). "Osteology of Arctodictis sinclairi (Mammalia, Metatheria, Sparassodonta) and phylogeny of Cenozoic metatherian carnivores from South America". Monografías del Museo Argentino de Ciencias Naturales. 6: 1–174.
  6. ^ Forasiepi, Analía M. (2009). "Additional data on early Paleocene metatherians (Mammalia) from Punta Peligro (Salamanca Formation, Argentina): comments based on petrosal morphology". Journal of Zoological Systematics and Evolutionary Research. 4: 391–398. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  7. ^ Marshall, Larry G. (1990). "Phylogenetic Relationships of the Families of Marsupials". Current Mammalogy. 2: 433–505. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  8. ^ Argot, Christine (2004). "Functional-adaptive analysis of the postcranial skeleton of a Laventan borhyaenoid, Lycopsis longirostris (Marsupialia, Metatheria)". Journal of Vertebrate Paleontology. 24 (3): 689–708. doi:10.1671/0272-4634(2004)024[0689:FAOTPS]2.0.CO;2.
  9. ^ Ercoli, Marcos D. (2012). "Form and function within a phylogenetic framework: locomotory habits of extant predators and some Miocene Sparassodonta". Zoological Journal of the Linnean Society. 165: 224–251. doi:10.1111/j.1096-3642.2011.00793.x?. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  10. ^ Argot, Christine (2011). "Postcranial morphology, functional adaptations and paleobiology of Callistoe vincei, a predaceous metatherian from the Eocene of Salta, north-western Argentina". Palaeontology. 54 (2): 447–480. doi:10.1111/j.1475-4983.2011.01036.x. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  11. ^ Babot, M. Judith (2008). "Primer registro de Borhyaenoidea (Mammalia, Metatheria, Sparassodonta) en la provincia de Tucuman (Formacion India Muerta, Grupo Choromoro; Mioceno tardio)". Acta Geologica Lilloana. 21 (1): 34–48. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  12. ^ a b Foraseipi, Analia M. (2007). "Revisión taxonómica de Parahyaenodon argentinus Ameghino y sus implicancias en el conocimiento de los grandes mamíferos carnívoros del Mio-Plioceno de América de Sur". Ameghiniana. 44 (1): 143–159. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  13. ^ Goin, Francisco J. (1996). "Revision de las especies del genero Hyperdidelphys Ameghino, 1904 (Mammalia, Marsupialia, Didelphidae. Su significacion filogenetica, estratigrafica y adaptativa en el Neogeno del Cono Sur sudamericano". Estudios Geologicos. 52: 327–359. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  14. ^ Prevosti, Francisco J. (2009). "Comment on "The oldest South American Cricetidae (Rodentia) and Mustelidae (Carnivora): Late Miocene faunal turnover in central Argentina and the Great American Biotic Interchange" by D.H. Verzi and C.I. Montalvo [Palaeogeography, Palaeoclimatology, Palaeoecology 267 (2008) 284–291]". Palaeogeography, Palaeoclimatology, Palaeoecology. 280 (3–4): 543–547. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  15. ^ de Muizon, Christian (1998). "Mayulestes ferox, a borhyaenoid (Metatheria, Mammalia) from the early Paleocene of Bolivia. Phylogenetic and palaeobiologic implications". Geodiversitas. 20: 19–142.
  16. ^ Forasiepi, Analia M. (2006). "A new species of Hathliacynidae (Metatheria, Sparassodonta) from the middle Miocene of Quebrada Honda, Bolivia". Journal of Vertebrate Paleontology. 26 (3): 670–684.
  17. ^ Forasiepi, Analía M. (2010). "A new thylacosmilid (Mammalia, Metatheria, Sparassodonta) from the Miocene of Patagonia, Argentina" (PDF). Zootaxa. 2552: 55–68. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)

Further reading

  • Ercoli, Marcos Darío (2012). "Form and function within a phylogenetic framework: locomotory habits of extant predators and some Miocene Sparassodonta (Metatheria)". Zoological Journal of the Linnean Society. 165 (1): 224–251. doi:10.1111/j.1096-3642.2011.00793.x. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
Wikisource has the text of the 1911 Encyclopædia Britannica article "Sparassodonta".
Retrieved from "https://en.wikipedia.org/w/index.php?title=Sparassodonta&oldid=585047057"