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Post by brobear on Mar 19, 2019 3:53:19 GMT -5
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Post by brobear on Mar 19, 2019 3:58:51 GMT -5
en.wikipedia.org/wiki/Plionarctos Plionarctos is an extinct genus of mammals of the family Ursidae (bears) endemic to North America and Europe during Miocene through Pleistocene, living from ~10.3—3.3 Mya, existing for about 7 million years. Indarctos (10.7—9.2 Mya) preceded Plionarctos by only a few thousand years and was a contemporary of that bear and shared its habitat. Plionarctus preceded and was also contemporary with Tremarctos floridanus (4.9 million — 11,000 years ago) and shared its habitat. Plionarctos is the oldest known genus within the subfamily of the short-faced bears (Tremarctinae) endemic to the Americas, and is believed to be ancestral to the clade. Two specimens were examined by Legendre and Roth for body mass. Specimen 1 was estimated to weigh 165.5 kg (360 lb). Specimen 2 was estimated to weigh 25.3 kg (56 lb).
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Post by brobear on Nov 1, 2019 1:09:15 GMT -5
bearsoftheworld.net/plionarctos.asp Plionarctos is the oldest known genus in Ursidae's subfamily Tremarctinae which contains short faced bears. It is believed to be ancestral to both the Arctodus and Tremarctos genus. Plionarctos evolved from the genus Ursavus (possibly Ursavus brevirhinus) and existed from 10.3 million to 3.3 million years ago, from the Mid-Miocene to the early Pliocene Epoch. The three known sub-species of Plionarctos are Plionarctos edensis, Plionarctos harroldorum, and Plionarctos telonensis. Plionarctos was assigned to the bear family Ursidae in 1926 by paleontologist Childs Frick and to the subfamily Tremarctinae by R. M. Hunt in 1998. The map below shows where Plionarctos fossils have been discovered.
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Post by brobear on Nov 13, 2019 5:56:22 GMT -5
With the recent short-faced bear fossil discovery in Tennessee (Gray Fossil Site), I thought some of the forum audience might be interested to know that there have been additional-similar fossil discoveries made in the western United States. We are still talking about the Tremarctine branch and Plionarctos lineage but earlier disovery. The following article reference is from 2001: ABSTRACT—The Pliocene Ringold Formation of eastern Washington has yielded important new materials of tremarctine bears of the anagenetic Plionarctos lineage. The genus is reviewed in light of this new material and observations made on other described specimens. One of these was previously described from the medial Hemphillian Rattlesnake Formation of Oregon and is recognized as a tremarctine bear, thus extending the earliest record of the group into the early part of the late Miocene. The late Hemphillian P. edensis, the genotypic species, is rediagnosed, although no new material is added to its hypodym. A new species from the early Blancan White Bluffs sites, P. harroldorum, appears to have been derived from P. edensis. Referred Plionarctos sp. from the medial Blancan Taunton Locality has some dental features that are more derived and approach those of the Pleistocene Tremarctos floridanus. Plionarctos forms a paraphyletic stem-group for the Tremarctinae. Species of this genus can be traced successively into the Pliocene where they form the stock from which the Pleistocene and Recent species of Tremarctos, Arctodus, and Pararctotherium arose. Tedford, R. H. & Martin, J. Plionarctos, a tremarctine bear (Ursidae; Carnivora) from western North America. J. Vert. Paleontol. 21, 311–321 (2001). www.bioone.org/doi/abs/10.1671/0272-4634%282001%29021%5B0311:PATBUC%5D2.0.CO%3B2
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Post by OldGreenGrolar on Nov 13, 2019 7:02:53 GMT -5
I wonder how many more extinct bears will be discovered.
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Post by brobear on Nov 13, 2019 7:13:32 GMT -5
I wonder how many more extinct bears will be discovered. Why I have from early childhood loved reading about prehistoric life - Each discovery, although very old, is new again on discovery day. Its kinda like finding life on another planet.
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Post by brobear on Jan 6, 2020 2:05:34 GMT -5
bearsoftheworld.net/plionarctos.asp Plionarctos is the oldest known genus in Ursidae's subfamily Tremarctinae which contains short faced bears. It is believed to be ancestral to both the Arctodus and Tremarctos genus. Plionarctos evolved from the genus Ursavus (possibly Ursavus brevirhinus) and existed from 10.3 million to 3.3 million years ago, from the Mid-Miocene to the early Pliocene Epoch. The three known sub-species of Plionarctos are Plionarctos edensis, Plionarctos harroldorum, and Plionarctos telonensis. Plionarctos was assigned to the bear family Ursidae in 1926 by paleontologist Childs Frick and to the subfamily Tremarctinae by R. M. Hunt in 1998. The map below shows where Plionarctos fossils have been discovered.
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Post by King Kodiak on Jan 6, 2020 19:39:48 GMT -5
Plionarctos, a tremarctine bear (Ursidae: Carnivora) from Western North America The Pliocene Ringold Formation of eastern Washington has yielded important new materials of tremarctine bears of the anagenetic Plionarctos lineage. The genus is reviewed in light of this new material and observations made on other described specimens. One of these was previously described from the medial Hemphillian Rattlesnake Formation of Oregon and is recognized as a tremarctine bear, thus extending the earliest record of the group into the early part of the late Miocene. The late Hemphillian P. edensis, the genotypic species, is rediagnosed, although no new material is added to its hypodym. A new species from the early Blancan White Bluffs sites, P. harroldorum, appears to have been derived from P. edensis. Referred Plionarctos sp. from the medial Blancan Taunton Locality has some dental features that are more derived and approach those of the Pleistocene Tremarctos floridanus. Plionarctos forms a paraphyletic stem-group for the Tremarctinae. Species of this genus can be traced successively into the Pliocene where they form the stock from which the Pleistocene and Recent species of Tremarctos, Arctodus, and Pararctotherium arose. Although in this case the pattern of homoplasy is not as evident as in the case of pandas, again the evidence from the fossil record of Potos and Tremarctos confirms the independent evolution of similar morphologies. In fact, the earlier tremarctine known from the fossil record is the early Miocene, North American Plionarctos, which retains a primitive tremarctine mandible without a premasseteric fossa ( Tedford & Martin, 2001). The Tertiary record of procyonids shows that some primitive procyonids like the Miocene Broiliana from Europe has a mesocarnivorous dentition ( Baskin, 1982Baskin, , 2004). ... The first tremarctines known in the fossil record are species of Plionarctos (P. edensis and P. harroldorum), recorded from several Mio-Pliocene localities of North America (Tedford & Martin 2001). Within the tremarctine phylogeny, Plionarctos is a paraphyletic stem-group from which more recent species of the Pleistocene emerged (Tedford & Martin 2001). ... ... edensis and P. harroldorum), recorded from several Mio-Pliocene localities of North America (Tedford & Martin 2001). Within the tremarctine phylogeny, Plionarctos is a paraphyletic stem-group from which more recent species of the Pleistocene emerged (Tedford & Martin 2001). This was the case of North American shortfaced bears (Arctodus simus and Arctodus pristinus) and the extinct spectacled bear (Tremarctos floridanus ), which dispersed across North America during most of the Pleistocene (Kurtén 1966, 1967). ... . The bear genera that constitute the subfamily Tre- marctinae (Carnivora: Ursidae) are distributed ex- clusively in America. Of these, Plionarctos is re- corded from the Late Miocene to the Early Pliocene of North America with two species (TEDFORD & MARTIN 2001). Arctodus contains two North Ameri- can Late Pliocene and Pleistocene species: A. pristinus and A. simus. ... www.google.com/amp/s/www.researchgate.net/publication/232679376_Plionarctos_a_tremarctine_bear_Ursidae_Carnivora_from_Western_North_America/amp
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Post by brobear on Dec 4, 2020 2:36:22 GMT -5
Subspecies: ( 1 ) Plionarctos edensis ( 2 ) Plionarctos harroldorum ( 3 ) Plionarctos telonensis.
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