Indarctos
{{Short description|Extinct genus of bears}}
{{Automatic taxobox
| fossil_range = Miocene, {{Fossil range|11.1|5.3}}
| image = Indarctos atticus.jpg
| image_caption = I. atticus skull, Natural History Museum of Basel
| taxon = Indarctos
| authority = Pilgrim, 1913
| type_species = †Indarctos salmontanus
| type_species_authority = Pilgrim, 1913
| subdivision_ranks = Species
| subdivision = †I. punjabiensis (Lydekker, 1884)
†I. sinensis (Zdansky, 1924)
†I. vireti (Villalta & Crusafont, 1943)
†I. arctoides (Deperet, 1895)
†I. anthracitis (Weithofer, 1888)
†I. salmontanus (Pilgrim, 1913)
†I. atticus (Weithofer, 1888)
†I. bakalovi (Kovachev, 1988)
†I. lagrelli (Zdansky, 1924)
†I. oregonensis (Merriam et al., 1916)
†I. nevadensis (Macdonald, 1959){{cite journal|last1=MacDonald|first1=J. R.|title=The Middle Pliocene Mammalian Fauna from Smiths Valley, Nevada|journal=Journal of Paleontology|date=1959|volume=33|issue=5|pages=872–887|jstor=1300922}}
}}
Indarctos is an extinct genus of bear, present in Africa, North America, and Eurasia during the Miocene. It was present from ~11.1 to 5.3 Ma, existing for approximately {{Mya|11.5-5.3|million years}}.
The oldest member is from Arizona (~11.1—7.7 Ma) and youngest is (~9.0—5.3 Ma) from Kazakhstan. In North America this animal was contemporary with Plionarctos (~10.3—3.3 Ma).
Discovery, history and taxonomy
= Discoveries =
A molar (designated to MNA 1839/km-83) discovered from the Karabulak formation in 1988 was tentatively assigned to Indarctos sp. In 2017 it was re examined and assigned to I. punjabensis. The tooth was found to belong to a young individual, which may be a male, and is the largest tooth known from the species. This might be due to sexual dimorphism since extant male bears are larger than the females.{{Cite web|title=Late Miocene Indarctos (Carnivora: Ursidae) from Kalmakpai Locality in Kazakhstan|url=https://www.zin.ru/journals/trudyzin/eng/publication.html?id=285|access-date=2020-12-22|website=www.zin.ru}}
= Species =
File:Rattlesnake Formation Mural.jpg]]
File:Indarctos oregonensis FLMNH.jpg]]
Indarctos is known from several species spread widely across Eurasia, North America, and North Africa, however, most of them are known from fragmentary remains which leaves us with insufficient knowledge of the anatomy, lifestyle, taxonomy and paleoecology of some species. These species are usually established based on poor remains, where the presence of sexual dimorphism, paleogeographical variation and individual variation is not taken into account, resulting in a number of species whose taxonomic validity is doubted.
The following are some species of this genus:
I. arctoides: This species had an omnivorous diet, and it was ancestral to the later I. punjabensis.
I. punjabiensis: This species is the geologically youngest and last species of Indarctos. It had a wide distribution 6.3–6.5 Ma during the Late Miocene, across Eurasia. It is known from the Karabulak formation of Kazakhstan, to China and the Dhon Pathan formation of Indo-Pakistan. It descended from the earlier I. arctoides, but unlike its ancestor, it was omnivorous and bigger in size. Based on the resemblance of its forelimbs to those of the modern brown bear, it possibly had similar locomotor adaptations. Evolutionary features such as this led to the migration of Indarctos-like bears into North America. At the end of the Late Miocene, Indarctos punjabiensis went extinct as the last species of its genus.
Description
I. arctoides was sexually dimorphic with males weighing {{convert|265|kg|lb|abbr=on}}, while females weighed {{convert|137|kg|lb|abbr=on}}.{{Cite journal |last=Abella |first=Juan |last2=Valenciano |first2=Alberto |last3=Pérez-Ramos |first3=Alejandro |display-authors=et al. |title=On the Socio-Sexual Behaviour of the Extinct Ursid Indarctos arctoides: An Approach Based on Its Baculum Size and Morphology |url=https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0073711 |journal=PLoS One}}
Distribution
File:On-the-Socio-Sexual-Behaviour-of-the-Extinct-Ursid-Indarctos-arctoides-An-Approach-Based-on-Its-pone.0073711.s002.ogv from I. arctoides.]]
Some sites and specimen ages:
- Box T Site, Lipscomb County, Texas ~9.3—9.2 Ma.
- Rattlesnake site, Grant County, Oregon ~10.3—4.9 Ma.
- Withlacoochee River Site 4A, Marion County, Florida (Indarctos sp.) ~10.3—4.9 Ma.
- Lufeng, Yunnan, China (I. atticus) ~9—5.3 Ma.
- Yulafli (CY), Thrace, Turkey (I. arctoides) ~9.7—8.7 Ma.
- Batallones-3, Madrid Basin, Spain (I. arctoides) ~11.6—5.3 Ma.[https://www.academia.edu/387025/El_sistema_de_yacimientos_de_mamiferos_miocenos_del_Cerro_de_los_Batallones_Cuenca_de_Madrid_estado_actual_y_perspectivas Batallones-3 site]Abella J, Valenciano A, Pérez-Ramos A, Montoya P, Morales J (2013) On the Socio-Sexual Behaviour of the Extinct Ursid Indarctos arctoides: An Approach Based on Its Baculum Size and Morphology. PLoS ONE 8(9): e73711. doi:10.1371/journal.pone.0073711
Paleoecology
In Kazakhstan, the species I. punjabiensis is known from the Karabulak formation which dates to 6.3–6.5 Ma (Late Miocene). It coexisted with three mustelids (Martes sp., Promeles sp., Plesiogulo crassa Teilhard), three feliforms (Adcrocuta eximia, Hyaenictitherium hyaenoides orlovi, Amphimachairodus kurteni), four perissodactyls (Hipparion hippidiodus, H. elegans, Chilotherium sp., Sinotherium zaisanensis), and six artiodactyls (Cervavitus novorossiae, Procapreolus latifrons, Samotherium cf. irtyshense, Paleotragus (Yuorlovia) asiaticus, Tragoportax sp., Gazella dorcadoides). The climate that Indarctos punjabensis lived in was mild and arid. It was a habitat of wide, open steppes.
References
{{Reflist}}
{{Ursidae extinct nav|state=collapsed}}
{{Taxonbar|from=Q2892917}}
Category:Fossil taxa described in 1913
Category:Miocene mammals of North America
Category:Miocene mammals of Asia
Category:Miocene mammals of Africa
Category:Prehistoric mammals of Europe
Category:Prehistoric carnivoran genera