Tremarctos: Difference between revisions
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{{Short description|Genus of bears}} | {{Short description|Genus of bears}} | ||
{{Automatic taxobox | {{Automatic taxobox | ||
| fossil_range = | | fossil_range = {{Fossil range|2.7|0}}<small> [[Late Pliocene]] - [[Holocene]]</small> | ||
| image = Spectacled Bear - Houston Zoo.jpg | | image = Spectacled Bear - Houston Zoo.jpg | ||
| image_caption = [[Spectacled bear]], ''Tremarctos ornatus'' | | image_caption = [[Spectacled bear]], ''Tremarctos ornatus'' | ||
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}} | }} | ||
'''''Tremarctos''''' is a [[genus]] of the [[Monophyly|monophyletic]] [[Ursidae|bear]] [[subfamily]] [[Tremarctinae]], endemic to [[Americas]] from the [[Pliocene]] to [[Holocene|recent]]. The northern species, the [[Tremarctos floridanus|Florida short-faced bear]], | '''''Tremarctos''''' is a [[genus]] of the [[Monophyly|monophyletic]] [[Ursidae|bear]] [[subfamily]] [[Tremarctinae]], endemic to [[Americas]] from the [[Pliocene]] to [[Holocene|recent]]. The northern species, the [[Tremarctos floridanus|Florida short-faced bear]], went extinct in the Late Pleistocene. The sole living ''Tremarctos'' species is the South American [[spectacled bear]]. ''Tremarctos'' is also the only living genus under the Tremarctinae subfamily, with the other genera, ''[[Plionarctos]], [[Arctodus]],'' and ''[[Arctotherium]]'' all being extinct. | ||
== | ==Taxonomy== | ||
* [[extinction|†]]''[[Tremarctos floridanus]]'' - Florida short-faced bear | * [[extinction|†]]''[[Tremarctos floridanus]]'' - Florida short-faced bear | ||
* ''[[Tremarctos ornatus]]'' - [[spectacled bear]] | * ''[[Tremarctos ornatus]]'' - [[spectacled bear]] | ||
== Evolution == | |||
{{Cladogram|{{clade| style=font-size:90%;line-height:90%; | |||
|1={{dagger}}[[Hemicyoninae]] | |||
|2={{Clade | |||
|1={{dagger}}[[Ursavinae]] | |||
|2={{Clade | |||
|1=[[Ailuropodinae]] [[File:Recherches pour servir à l'histoire naturelle des mammifères (Pl. 50) (white background).jpg|75px]] | |||
|2={{Clade | |||
|1=[[Ursinae]] [[File:Ursus arctos - 1700-1880 - Print - Iconographia Zoologica - Special Collections University of Amsterdam - (white background).jpg|75px]] | |||
|2={{Clade | |||
|label1=[[Tremarctinae]] (short-faced bears) | |||
|1={{Clade | |||
|1={{dagger}}''[[Plionarctos]]'' | |||
|2={{Clade | |||
|1={{dagger}}''[[Arctodus]]'' | |||
|2={{Clade | |||
|1='''''Tremarctos''''' [[File:Spectacled bear (1829).jpg|75px]] | |||
|2={{dagger}}''[[Arctotherium]]'' | |||
}} }} }} }} }} }} }} }}<nowiki></nowiki>|title=[[Tremarctinae]] within [[Ursidae]]|align=left}}''Tremarctos'' belongs to the subfamily Tremarctinae, which first appeared as ''[[Plionarctos]]'' during the [[late Miocene]] epoch of North America. Plionarctos is also believed to be the ancestor of all subsequent Tremarctine bears (''Arctodus'', ''Arctotherium'' and ''Tremarctos'').<ref name="Mitchell-2016">{{Cite journal |last1=Mitchell |first1=Kieren J. |last2=Bray |first2=Sarah C. |last3=Bover |first3=Pere |last4=Soibelzon |first4=Leopoldo |last5=Schubert |first5=Blaine W. |last6=Prevosti |first6=Francisco |last7=Prieto |first7=Alfredo |last8=Martin |first8=Fabiana |last9=Austin |first9=Jeremy J. |last10=Cooper |first10=Alan |date=2016-04-30 |title=Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America |journal=Biology Letters |volume=12 |issue=4 |page=20160062 |doi=10.1098/rsbl.2016.0062 |pmc=4881349 |pmid=27095265}}</ref> The genetic divergence date for ''Arctodus'' is between 5.5 million years ago and 4.8 million years ago,<ref name="Pedersen 2728–2736.e8">{{Cite journal |last1=Pedersen |first1=Mikkel Winther |last2=De Sanctis |first2=Bianca |last3=Saremi |first3=Nedda F. |last4=Sikora |first4=Martin |last5=Puckett |first5=Emily E. |last6=Gu |first6=Zhenquan |last7=Moon |first7=Katherine L. |last8=Kapp |first8=Joshua D. |last9=Vinner |first9=Lasse |last10=Vardanyan |first10=Zaruhi |last11=Ardelean |first11=Ciprian F. |date=2021-06-21 |title=Environmental genomics of Late Pleistocene black bears and giant short-faced bears |journal=Current Biology |volume=31 |issue=12 |pages=2728–2736.e8 |bibcode=2021CBio...31E2728P |doi=10.1016/j.cub.2021.04.027 |hdl=10037/22808 |pmid=33878301 |s2cid=233303447 |hdl-access=free}}</ref><ref name="Mitchell-2016" /> and between between ''Arctotherium'' and ''Tremarctos'' at 4.1 million years ago.<ref name="Mitchell-2016" /> This genetic divergence occurred around the [[Late Miocene|Miocene]]-[[Zanclean|Pliocene]] boundary, when tremarctine bears, along with other ursids, experienced an explosive radiation in diversity, as [[C4 carbon fixation|C<sub>4</sub> vegetation]] ([[Poaceae|grasses]]) and open habitats dominated. The world experienced a major temperature drop and increased seasonality, and a faunal turnover which extinguished 70–80% of North American genera.<ref>{{Cite journal |last1=Krause |first1=Johannes |last2=Unger |first2=Tina |last3=Noçon |first3=Aline |last4=Malaspinas |first4=Anna-Sapfo |last5=Kolokotronis |first5=Sergios-Orestis |last6=Stiller |first6=Mathias |last7=Soibelzon |first7=Leopoldo |last8=Spriggs |first8=Helen |last9=Dear |first9=Paul H |last10=Briggs |first10=Adrian W |last11=Bray |first11=Sarah CE |last12=O'Brien |first12=Stephen J |last13=Rabeder |first13=Gernot |last14=Matheus |first14=Paul |last15=Cooper |first15=Alan |date=December 2008 |title=Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary |journal=BMC Evolutionary Biology |language=en |volume=8 |issue=1 |page=220 |bibcode=2008BMCEE...8..220K |doi=10.1186/1471-2148-8-220 |issn=1471-2148 |pmc=2518930 |pmid=18662376 |doi-access=free}}</ref><ref name="Donohue2">{{cite journal |last1=Donohue |first1=Shelly L. |last2=DeSantis |first2=Larisa R. G. |last3=Schubert |first3=Blaine W. |last4=Ungar |first4=Peter S. |date=30 October 2013 |title=Was the giant short-faced bear a hyper-scavenger? A new approach to the dietary study of ursids using dental microwear textures |journal=PLOS ONE |volume=8 |issue=10 |page=e77531 |bibcode=2013PLoSO...877531D |doi=10.1371/journal.pone.0077531 |pmc=3813673 |pmid=24204860 |doi-access=free}}</ref> | |||
The medium-sized ''Arctodus pristinus,'' ''[[Tremarctos floridanus]]'' and ''Arctotherium sp.'' evolved from ''Plionarctos'' in the [[Blancan]] [[Blancan|faunal age]] of North America, being first recorded ca. 2.6Ma.<ref name="Emslie-19952">{{cite journal |last1=Emslie |first1=Steven D. |year=1995 |title=The fossil record of Arctodus pristinus (Ursidae: Tremarctinae) in Florida |url=https://www.floridamuseum.ufl.edu/wp-content/uploads/sites/35/2017/03/Vol-37-No-15.pdf |journal=Bulletin of the Florida Museum of Natural History |volume=37 |issue=15 |pages=501–514 |doi=10.58782/flmnh.hduf9651 |s2cid=168164209}}</ref><ref>{{Cite journal |last1=Soibelzon |first1=Leopoldo H. |last2=Romero |first2=M.R. Aguilar |date=2008-10-14 |title=A Blancan (Pliocene) short-faced bear from El Salvador and its implications for Tremarctines in South America |url=http://sedici.unlp.edu.ar/handle/10915/5361 |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=250 |issue=1 |pages=1–8 |doi=10.1127/0077-7749/2008/0250-0001}}</ref><ref name="Schubert-2010a2">{{Cite journal |last1=Schubert |first1=Blaine |last2=Hulbert |first2=Richard |last3=MacFadden |first3=Bruce |last4=Searle |first4=Michael |last5=Searle |first5=Seina |date=2010-01-01 |title=Giant Short-faced Bears (Arctodus simus) in Pleistocene Florida USA, a Substantial Range Extension |url=https://www.researchgate.net/publication/250071137 |journal=Journal of Paleontology |volume=84 |issue=1 |pages=79–87 |bibcode=2010JPal...84...79S |doi=10.1666/09-113.1 |s2cid=131532424}}</ref> ''T. floridanus'' is last dated to around 23,200 years ago.<ref>{{Cite journal |last=Haynes |first=Gary |date=2013-02-08 |title=Extinctions in North America's Late Glacial landscapes |url=https://www.sciencedirect.com/science/article/pii/S104061821000296X |journal=Quaternary International |series=Peopling the last new worlds: the first colonisation of Sahul and the Americas |volume=285 |pages=89–98 |bibcode=2013QuInt.285...89H |doi=10.1016/j.quaint.2010.07.026 |issn=1040-6182 |url-access=subscription}}</ref><ref name=":35">{{Cite journal |last1=Faith |first1=J. Tyler |last2=Surovell |first2=Todd A. |date=2009-12-08 |title=Synchronous extinction of North America's Pleistocene mammals |journal=Proceedings of the National Academy of Sciences |language=en |volume=106 |issue=49 |pages=20641–20645 |bibcode=2009PNAS..10620641F |doi=10.1073/pnas.0908153106 |issn=0027-8424 |pmc=2791611 |pmid=19934040 |doi-access=free}}</ref> | |||
== Habitat == | == Habitat == | ||
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=== Size === | === Size === | ||
Species under the ''Tremartcos'' genus are about average-sized bears, similar in size to the [[American black bear | Species under the ''Tremartcos'' genus are about average-sized bears, similar in size to the [[American black bear]]. They can weigh anywhere from 150 to 400 lbs. The ''Tremarctos Floridanus'' however, was bigger than ''Tremarctos Orantus''. Both species are [[Sexual dimorphism|sexually dimorphic]], meaning the males are most times larger than the females in size. This also results in the males having protein blood levels higher than the females' levels.<ref name=":1" /> The forelimbs of ''Tremarctos'' bears are longer than their hindlimbs. | ||
=== Morphology === | === Morphology === | ||
Latest revision as of 07:20, 1 July 2025
Template:Short description Template:Automatic taxobox
Tremarctos is a genus of the monophyletic bear subfamily Tremarctinae, endemic to Americas from the Pliocene to recent. The northern species, the Florida short-faced bear, went extinct in the Late Pleistocene. The sole living Tremarctos species is the South American spectacled bear. Tremarctos is also the only living genus under the Tremarctinae subfamily, with the other genera, Plionarctos, Arctodus, and Arctotherium all being extinct.
Taxonomy
- †Tremarctos floridanus - Florida short-faced bear
- Tremarctos ornatus - spectacled bear
Evolution
Template:CladogramTremarctos belongs to the subfamily Tremarctinae, which first appeared as Plionarctos during the late Miocene epoch of North America. Plionarctos is also believed to be the ancestor of all subsequent Tremarctine bears (Arctodus, Arctotherium and Tremarctos).[1] The genetic divergence date for Arctodus is between 5.5 million years ago and 4.8 million years ago,[2][1] and between between Arctotherium and Tremarctos at 4.1 million years ago.[1] This genetic divergence occurred around the Miocene-Pliocene boundary, when tremarctine bears, along with other ursids, experienced an explosive radiation in diversity, as C4 vegetation (grasses) and open habitats dominated. The world experienced a major temperature drop and increased seasonality, and a faunal turnover which extinguished 70–80% of North American genera.[3][4]
The medium-sized Arctodus pristinus, Tremarctos floridanus and Arctotherium sp. evolved from Plionarctos in the Blancan faunal age of North America, being first recorded ca. 2.6Ma.[5][6][7] T. floridanus is last dated to around 23,200 years ago.[8][9]
Habitat
Tremarctos floridanus bears lived in the southern parts of North America. Tremarctos ornatus however lives in South America,[10] such as in the Andes Mountains of Peru.[11] They also live in countries like Bolivia and Venezuela.[12] Tremarctos orantus is the only species of bear to live in South America. They like to build nests that they use to sleep and eat in, in trees of high elevation in humid tropical rain forests.[13] They are able to live in other types of biomes too such as temperate grasslands, deciduous forests, and more. Where they choose to live is dependent upon the type of food/resources that are available in the habitat.[11]
Diet
The diet of Tremarctos bears is varied. They are considered omnivores as they eat fruit, corn, plants, insects, farm animals, and more.[13]
Species under this genus are able to use their paws to manipulate food. They can strip leaves off of trees, pick apart fruits, grasp food, etc. They do this with the help of having a radius sesamoid, also referred to as a "false thumb".[14]
Hunting and eating take up most of a Tremarctos bears activity levels. Tremarctos bears are diturnal meaning that they will hunt during either the day, evening, or night, meaning they do not hibernate. It depends on where the bear is located and what the current season is that determines when they are the most active.[12]
Etymology
The genus name Tremarctos was created in 1855 by Alfred Gervais.[14] While his suggestion for making Tremarctos a separate genus was rejected, after further studies comparing skeletal structures of the teeth and jaws of Tremarctos to other bear species his suggestion was later then accepted.[11]
The word Tremarctos is derived from the Greek language and translates to "hole bear" in English. If one were to look at humerus of this type of bear, one would notice a hole in the middle of it. This is where its name comes from and why it is called the "hole bear".[15] However, the name "hole bear" could also come from the fact that the tan facial markings appear on the face except around the bear's eyes, making it look like the bear has holes for eyes, giving it the Jukumari in the Andean culture.[15]
Physical Characteristics
Size
Species under the Tremartcos genus are about average-sized bears, similar in size to the American black bear. They can weigh anywhere from 150 to 400 lbs. The Tremarctos Floridanus however, was bigger than Tremarctos Orantus. Both species are sexually dimorphic, meaning the males are most times larger than the females in size. This also results in the males having protein blood levels higher than the females' levels.[12] The forelimbs of Tremarctos bears are longer than their hindlimbs.
Morphology
They have long curved claws and have plantigrade feet.[11] As for their fur, they are usually black with a tannish marking that extends from their chest to around their face. While Tremarctos Floridanus's exact appearance is unknown, they presumably resembled the Tremarctos Ornatus. Although they have large, deep skulls, they are the smallest in length among the bear species.[12]
Dentation
The species under the Tremarctos genus have short mandibles as well as short crania. Even though they are omnivores, the evidence of having short mandibles and crania indicates they feed mostly on plants and fruits and only sometimes eat meat. Because of this they also have resilient teeth near their cheeks. They also have small canines and large molars showing they eat meat as well.[16] They have 42 teeth.
Breeding
Courtship occurs between male and female Tremarctos bears and this usually involves vocalizations or playful fighting. Tremarctos are polygamous meaning the male bears breed with multiple female bears. They are also polyesterous, meaning the bears have specific breeding seasons with twins being the most common litter. Cubs are usually born during seasons when fruits and vegetables are growing and becoming ripe.[12]
The mothering bears create dens for raising their offspring. When the cubs are born, their eyes are closed and they lack teeth.[15] The mothers will care for the cubs for about three years and after which, they separate.[12] Male Tremarctos bears tend to live longer than females.[11]
Threats
While the Tremarctos bear is higher up on the food chain, it still has a couple of predators and other things that threaten them. With Tremarctos floridanus extinct, Tremarctos ornatus is the only living species of this genus, their population is slowly declining and they are considered vulnerable on the Threatened Species List. One of the biggest reasons for their decline is due to humans poaching and causing their habitat loss. In some locations they encounter predators such as jaguars and cougars. They are also susceptible to parasites such as ticks and nematodes as well as diseases such as alopecia and neoplasia.[15]
References
Template:ReflistTemplate:Carnivora Template:Taxonbar
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