Gondwanatheria

Gondwanatheria
Temporal range: Campanian-Miocene, 70.6–17.5 Ma
(possible Jurassic occurrence)
Mandible of Sudamerica
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Order:Therapsida
Suborder:Cynodontia
Clade:†Gondwanatheria
Mones, 1987
Subgroups

Gondwanatheria is an extinct group of mammals that lived in the Southern Hemisphere, including Antarctica, during the Upper Cretaceous through the Miocene (and possibly much earlier, if Allostaffia is a member of this group[3]). They are known only from isolated teeth, a few lower jaws, two partial skulls and one complete cranium.[4] Because of this fragmentary knowledge their placement is not clear.

Classification

Life reconstruction of Vintana sertichi. Postcranial reconstruction is hypothetical.

For several decades the affinities of the group were not clear, being first interpreted as early xenarthrans, or "toothless" mammals similar to the modern anteater. A variety of studies have since confirmed their position as allotheres related to multituberculates, possibly even true multituberculates, closer to cimolodonts than "plagiaulacidans" are.[1][5][6][7] However, a more recent study recovered them as nested among haramiyidans, rendering them as non-mammalian cynodonts.[8]

There are three known families within Gondwanatheria. The family Sudamericidae was named by Scillato-Yané and Pascual in 1984, and includes the vast majority of named taxa. The family Ferugliotheriidae was named by José Bonaparte in 1986, and includes one genus, Ferugliotherium, and possibly a few other forms like Trapalcotherium. Groeberiidae, originally interpreted as paucituberculate marsupials, has since been understood as gondwanatherians, though only the type genus, Groeberia, has been examined as such.[1]

Gondwanatheria cladogram per Chimento et al. 2015.

Further fossils have come from India, Madagascar and Antarctica. A possible Ferugliotherium-like species occurs in Maastrichtian deposits of Mexico, extending the clade to North America.[9]

The Miocene (Colhuehuapian) genus Patagonia is the youngest known representative.[1]

Biology

Gondwanatheres known from cranial remains almost universally have deep, robust snouts, as befitting their specialised herbivorous lifestyle. Groeberia and Vintana both possess bizarre jugal flanges similar to those of xenarthrans like ground sloths, though they had a palinal (front-to-back) chewing method as in most allotheres and unlike almost any therian.[10][1] Most gondwanatheres are specialised grazers, even being among the first mammals to have specialised for grass-eating long before any therians did, with the exceptions of Groeberidae and Ferugliotheriidae, which lack hyopsodont teeth and therefore had more generalistic herbivorous habits.

An articulated specimen found in the Maevarano Formation offers insight to the postcranial skeleton of these animals. Among the bizarre and unique features are a mediolaterally compressed and antero-posteriorly bowed tibia, a double trochlea on the astragalus, a fully developed humeral trochlea, and an unusually high number of trunk vertebrae. The new taxon has at least 19 rib-bearing (thoracic) and 11 non-rib-bearing (lumbar) vertebrae. Aside from these derived features, the Malagasy mammal has a mosaic pectoral girdle morphology: the procoracoid is lost, the coracoid is extremely well developed (into an enlarged process that contributes to half of the glenoid fossa), the interclavicle is small, and the sternoclavicular joint appears mobile. A ventrally facing glenoid and the well-developed humeral trochlea suggest a relatively parasagittal posture for the forelimbs. Remarkable features of the hind limb and pelvic girdle include a large obturator foramen similar in size to that of therians, a large parafibula, and the presence of an epipubic bone.[11]

Taxonomy

Order †Gondwanatheria[12][13] McKenna 1971 [Gondwanatheroidea Krause & Bonaparte 1993]

References

  1. 1 2 3 4 5 Nicolás R. Chimento, Federico L. Agnolin and Fernando E. Novas (2015). "The bizarre 'metatherians' Groeberia and Patagonia, late surviving members of gondwanatherian mammals". Historical Biology: An International Journal of Paleobiology. 27 (5): 603–623. doi:10.1080/08912963.2014.903945.
  2. ↑ Francisco J. Goin, Marcelo F. Tejedor, Laura Chornogubsky, Guillermo M. López, Javier N. Gelfo, Mariano Bond, Michael O. Woodburne, Yamila Gurovich, Marcelo Reguero (2012). "Persistence of a Mesozoic, non-therian mammalian lineage (Gondwanatheria) in the mid-Paleogene of Patagonia". Naturwissenschaften. 99 (6): 449–463. Bibcode:2012NW.....99..449G. doi:10.1007/s00114-012-0919-z. PMID 22584426.
  3. ↑ Nicholas Chimento, Frederico Agnolin, Agustin Martinelli, Mesozoic Mammals from South America: Implications for understanding early mammalian faunas from Gondwana, May 2016
  4. ↑ Kraus, David W. (2014). Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar. [Lincoln, NE]: Society of Vertebrate Paleontology. pp. 1–2.
  5. ↑ Krause, David W.; Hoffmann, Simone; Wible, John R.; Kirk, E. Christopher; Schultz, Julia A.; von Koenigswald, Wighart; Groenke, Joseph R.; Rossie, James B. (2014-11-05). O'Connor, Patrick M., Seiffert, Erik R., Dumont, Elizabeth R., Holloway, Waymon L., Rogers, Raymond R., Rahantarisoa, Lydia J., Kemp, Addison D., Andriamialison, Haingoson. "First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism". Nature. Nature Publishing Group, a division of Macmillan Publishers Limited. 515: 512–517. Bibcode:2014Natur.515..512K. doi:10.1038/nature13922. ISSN 1476-4687. PMID 25383528.
  6. ↑ Drake, Nadia (November 5, 2014). "Fossil From Dinosaur Era Reveals Big Mammal With Super Senses". nationalgeographic.com. National Geographic Society. Retrieved November 5, 2014.
  7. ↑ Wilford, John Noble (November 5, 2014). "Fossil's Unusual Size and Location Offer Clues in Evolution of Mammals". New York Times. Retrieved November 6, 2014.
  8. ↑ Huttenlocker, Adam K.; rossnickle, David M.; Kirkland, Jam,es I.; Schultz, Julia A.; Luo, Zhe-Xi (23 May 2018). "Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana". Nature. doi:10.1038/s41586-018-0126-y. Retrieved 23 May 2018.
  9. ↑ SVP 2015
  10. ↑ Krause, David W.; Hoffmann, Simone; Wible, John R.; Kirk, E. Christopher; Schultz, Julia A.; von Koenigswald, Wighart; Groenke, Joseph R.; Rossie, James B. (2014-11-05). O'Connor, Patrick M., Seiffert, Erik R., Dumont, Elizabeth R., Holloway, Waymon L., Rogers, Raymond R., Rahantarisoa, Lydia J., Kemp, Addison D., Andriamialison, Haingoson. "First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism". Nature. Nature Publishing Group, a division of Macmillan Publishers Limited. online. doi:10.1038/nature13922. ISSN 1476-4687.
  11. ↑ HOFFMANN, Simone, THE FIRST POSTCRANIAL REMAINS OF A GONDWANATHERIAN MAMMAL, October 2016
  12. ↑ Mikko's Phylogeny Archive Haaramo, Mikko (2007). "†Gondwanatheria – gondwanatheres". Retrieved 30 December 2015.
  13. ↑ Paleofile.com (net, info) "Archived copy". Archived from the original on 2016-01-11. Retrieved 2015-12-30. . "Taxonomic lists- Mammals". Retrieved 30 December 2015.
  14. ↑ Nicholas Chimento, Frederico Agnolin, Agustin Martinelli, Mesozoic Mammals from South America: Implications for understanding early mammalian faunas from Gondwana, May 2016
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.