Tylopoda

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Tylopoda
Temporal range: Early Eocene–Holocene
A dromedary camel
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Suborder: Tylopoda
Illiger, 1811
Families

Camelidae
and numerous

prehistoric
families (see text)

Tylopoda (meaning "calloused foot")

native ranges of South America and Asia, while Australian feral camels are introduced. The group has a long fossil history in North America and Eurasia. Tylopoda appeared during the Eocene
around 50 million years ago.

Tylopoda has only one

extant family, Camelidae, which includes camels, llamas, guanacos, alpacas and vicuñas. This group was much more diverse in the past, containing a number of extinct families
in addition to the ancestors of living camelids (see below).

Tylopods are not

ruminants.[2]

Taxonomy and systematics

Tylopoda was named by Illiger (1811) and considered

Cetartiodactyla by Ursing et al. (2000) and by Agnarsson and May-Collado (2008).[3][4][5]

The main problem with circumscription of Tylopoda is that the extensive fossil record of camel-like mammals has not yet been thoroughly examined from a

cladistic standpoint. Tylopoda is a highly distinctive lineage among the artiodactyls, but its exact relationships are somewhat elusive because the six living species are all closely related and can be considered "living fossils", the sole surviving lineage of a prehistorically wildly successful radiation. More recent studies suggest that tylopods are not as closely related to ruminants as traditionally believed, expressed in cladogram form as:[6][7][8][9][10][11]

Artiodactyla
 

Tylopoda (camels)

 Artiofabula 

  Suina (pigs)

 Cetruminantia 

 

Ruminantia (ruminants)
 

 
Cetancodonta/Whippomorpha
 

 Hippopotamidae (hippopotamuses)

 Cetacea (whales)

Tylopoda are

even-toed ungulates and relatives means that the oldest members of this lineage are still morphologically very primitive and hard to distinguish from the ancestors of related lineages. The first major modern and comprehensive analysis of the problem (in 2009) supported this; while some taxa traditionally considered Tylopoda could be confirmed to belong to this suborder (and a few refuted), the delimitation of this group is still very much disputed despite (or because of) an extensive fossil record.[6]

Life restoration of Agriochoerus antiquus

The taxa currently assigned (with some reliability) to Tylopoda are:[6]

Basal and incertae sedis

Superfamily †Anoplotherioidea

Superfamily Cameloidea

Superfamily †Merycoidodontoidea (=Oreodontoidea)

  • Family †"
    paraphyletic
    )
  • Family †
    Merycoidodontidae

Superfamily †

Xiphodontoidea

Life restoration of the primitive artiodactyl Diacodexis pakistanensis (foreground) being stalked by Pakicetus

Disputed Tylopoda

Several additional prehistoric

(cet)artiodactyl
taxa are sometimes assigned to the Tylopoda, but other authors consider them incertae sedis or basal lineages among the (Cet)artiodactyla:

Some studies have considered

ruminants.[12]

References

  1. ^ Donnegan, James (1834). "A New Greek and English Lexicon"
  2. ^ Fowler, M.E. (2010). "Medicine and Surgery of Camelids", Ames, Iowa: Wiley-Blackwell. Chapter 1, General Biology and Evolution, addresses the fact that camelids (including llamas and camels) are not ruminants, pseudoruminants, or modified ruminants.
  3. hdl:2246/1442
    .
  4. ^ R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698
  5. S2CID 84619585
    .
  6. ^
    doi:10.1371/journal.pone.0007062 article
  7. PMID 17101039
    .
  8. S2CID 206544776
    .
  9. PMID 22930817
    .
  10. PMID 22628470
    .
  11. PMID 31800571
    .(see e.g. Fig S10)
  12. PMID 34324518
    .

External links

Wikimedia Commons has media related to Tylopoda.


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