Haramiyida

Haramiyida
Temporal range: Late Triassic-Late Cretaceous, 216.5–65 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Clade: Haramiyida
Hahn, Sigogneau-Russell & Wouters, 1989
Subgroups

Haramiyidans seem to be the earliest known herbivores amongst basal mammals. Their teeth, which are by far the most common remains, resemble those of the multituberculates. However, based on Haramiyavia, the jaw is less derived; and at the level of evolution of earlier basal mammals like Morganucodon and Kuehneotherium, with a groove for ear ossicles on the dentary.[1] They are the longest lived mammalian clade of all time. However, a more recent study, in November 2015, may dispute this and suggested the Haramiyida were not mammals after all, but were part of a more ancestral side branch instead.[2][3]

Relationships

Haramiyids show certain similarities to multituberculates, a group of mammals that survived until about 40 million years ago. So it's possible that haramiyids are ancestral to multituberculates, although the available evidence is insufficient to be conclusive. Certain characteristics of the teeth seem to rule out a special relationship between the two groups,[4] although some scientists still unite haramiyids (or at least euharamiyids) and multituberculates in the Allotheria hypothesis.[5]

Taxonomy

For a long time it was unknown if haramiyids were crown-group mammals, or if they should be placed in the stem-group Mammaliaformes. This uncertainty stems from the fact that haramiyid remains were mostly restricted to teeth and jaw fragments. However, new discoveries of much more complete haramiyid fossils have settled the issueharamiyids are undoubtedly crown-group mammals. For example, the specimens show evidence of a typical mammalian middle ear, the area just inside the eardrum that turns vibrations in the air into ripples in the ear's fluids.[6] The middle ears of mammals are unique in that they have three bones, as evidenced in the new fossils.

Order †Haramiyida[7][8] Hahn, Sigogneau-Russell & Wouters 1989 [Haramiyoidea Hahn 1973 sensu McKenna & Bell 1997]

Lifestyle

Haramiyids seem to have been the first herbivores among the basal mammals. At least some species were very good climbers and were similar to modern day squirrels.[9]

Range

Most fossils have been reported from Europe, but some are known from Africa and Greenland. Since 2005, the published range extended to Mongolia and China. The age of haramiyid fossils range from Upper Triassic up to Late Cretaceous. This has important implications: the fact that haramiyids were present in the Late Triassic supports the idea that crown-group mammals originated at least 208 million years ago, much earlier than some previous research suggests.

The youngest haramiyid fossil genus is Avashishta bacharamensis from the Maastrichtian of India. Cretaceous haramiyids are previously known from the Early Cretaceous of Morocco, suggesting that these animals may have survived in gondwannan landmasses as relics. With a temporal range of at least 150 million years, they are the longest lived mammalian lineage.[10][11]

Notes

  1. Butler PM, 2000
  2. Chang, Kenneth (16 November 2015). "Jawbone in Rock May Clear Up a Mammal Family Mystery". New York Times. Retrieved 17 November 2015.
  3. Luo, Zhe-Xi; Gates, Stephen M.; Jenkins Jr., Farish A.; Amaral, William W.; Shubin, Neil H. (16 November 2015). "Mandibular and dental characteristics of Late Triassic mammaliaform Haramiyavia and their ramifications for basal mammal evolution". PNAS. doi:10.1073/pnas.1519387112. Retrieved 17 November 2015.
  4. Monastersky 1996, p.379
  5. Butler & Hooker 2005, p.206
  6. Shundong Bi, Yuanqing Wang, Jian Guan,Xia Sheng, Jin Meng (2014). "Three new Jurassic euharamiyidan species reinforce early divergence of mammals". Nature. doi:10.1038/nature13718. horizontal tab character in |author= at position 13 (help)
  7. Mikko's Phylogeny Archive Haaramo, Mikko (2007). "†Haramiyida". Retrieved 30 December 2015.
  8. Paleofile.com (net, info) . "Taxonomic lists- Mammals". Retrieved 30 December 2015.
  9. "Three extinct squirrel-like species discovered". ScienceDaily. 2014-09-11. Archived from the original on 18 September 2014. Retrieved 2014-10-07.
  10. S. Anantharaman, G. P. Wilson, D. C. Das Sarma and W. A. Clemens. 2006. A possible Late Cretaceous "haramiyidan" from India. Journal of Vertebrate Paleontology 26(2):488-490
  11. Ashok Sahni, New evidence for palaeogeographic intercontinental Gondwana relationships based on Late Cretaceous-Earliest Palaeocene coastal faunas from peninsular India, Washington DC American Geophysical Union Geophysical Monograph Series 01/1987; 41:207-218. DOI: 10.1029/GM041p0207

External links

References

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