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Bears of the Pleistocene
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5059403/
Retreat and extinction of the Late Pleistocene cave bear (Ursus spelaeus sensu lato) The cave bear (Ursus spelaeus sensu lato) is a typical representative of Pleistocene megafauna which became extinct at the end of the Last Glacial. Detailed knowledge of cave bear extinction could explain this spectacular ecological transformation. The paper provides a report on the youngest remains of the cave bear dated to 20,930 ± 140 14C years before present (BP). Ancient DNA analyses proved its affiliation to the Ursus ingressus haplotype. Using this record and 205 other dates, we determined, following eight approaches, the extinction time of this mammal at 26,100–24,300 cal. years BP. The time is only slightly earlier, i.e. 27,000–26,100 cal. years BP, when young dates without associated collagen data are excluded. The demise of cave bear falls within the coldest phase of the last glacial period, Greenland Stadial 3. This finding and the significant decrease in the cave bear records with cooling indicate that the drastic climatic changes were responsible for its extinction. Climate deterioration lowered vegetation productivity, on which the cave bear strongly depended as a strict herbivore. The distribution of the last cave bear records in Europe suggests that this animal was vanishing by fragmentation into subpopulations occupying small habitats. One of them was the Kraków-Częstochowa Upland in Poland, where we discovered the latest record of the cave bear and also two other, younger than 25,000 14C years BP. The relatively long survival of this bear in karst regions may result from suitable microclimate and continuous access to water provided by deep aquifers, indicating a refugial role of such regions in the Pleistocene for many species. The extinction of large-bodied mammals (called megafauna) is one of the most characteristic and inherent features of the Late Pleistocene. The disappearance began 50,000 years ago and affected a substantial number of mammalian genera, e.g. 36 % of them in Eurasia, 72 % in North America and 83 % in South America (Barnosky et al. 2004). Both the climate and environment changes, as well as human influence, are believed to be the main causes of this extinction (Barnosky et al. 2004; Cooper et al. 2015; Koch and Barnosky 2006; Lorenzen et al. 2011; Stuart 2015). The climate shift was sufficient to explain the fauna transformation in some cases, but in others, a combination of climatic and anthropogenic effects was most probably responsible for this phenomenon (Cooper et al. 2015; Lorenzen et al. 2011). A typical representative of megafauna is the cave bear (Ursus spelaeus sensu lato), which was one of the most widespread mammals in Eurasia in the Late Pleistocene. It evolved from Middle Pleistocene Ursus deningeri and developed into several forms which can be distinguished at morphological and genetic levels. Two main European forms in the species rank, which diverged probably between 414,000 and 173,000 years ago, were identified as Ursus ingressus, which inhabited south-eastern and central Europe as well as the Ural (Baca et al. 2014; Rabeder et al. 2004b), and U. spelaeus, which lived mainly in western Europe, although its remains were found also in the Altai (Knapp et al. 2009; Rabeder et al. 2004b). According to the rules of the International Code of Zoological Nomenclature, U. ingressus should, however, be called Ursus kanivetz, because under the latter name a bear from Medvezhiya Cave in the Ural was first described by Vereshchagin (1973) (see also Baryshnikov and Puzachenko (2011)). Further studies of ancient DNA showed that the haplotype from Medvezhiya Cave is clustered with others from Europe, described as U. ingressus (Baca et al. 2012; Knapp et al. 2009). Additionally, two small cave bear forms that had preserved some primitive traits were distinguished as subspecies of U. spelaeus: U. spelaeus eremus and U. spelaeus ladinicus (Rabeder and Hofreiter 2004; Rabeder et al. 2004a). Their distribution was confined to the high alpine caves in Austria and Italy. Recently, another major group of large cave bears from the Caucasus and the Yana River region in eastern Siberia was discovered (Baryshnikov 1998; Knapp et al. 2009). Initially, they were named Ursus deningeri kudarensis, but recent genetic studies suggest that they should be considered a third species, U rsus kudarensis (Stiller et al. 2014). By the end of the Pleistocene, all these cave bear forms were extinct and the causes and timing of this process have been debated over the recent years. Direct radiocarbon dating indicates that the last cave bears became extinct prior to the Last Glacial Maximum (LGM) and disappeared from fossil record quite simultaneously in different parts of Europe about 24,000 14C years before present (BP) (about 28,000 cal. years BP) (Bocherens et al. 2014; Hofreiter et al. 2002; Martini et al. 2014; Pacher and Stuart 2009; Sabol et al. 2014; Wojtal et al. 2015). Paleogenetic analyses showed, nonetheless, that the demise of cave bears started ca. 50,000 radiocarbon years BP (Stiller et al. 2010), thus about 25,000 years before their final extinction. It has been argued that apart from the changing climate (Pacher and Stuart 2009; Stuart and Lister 2007), several other factors contributed to the decline of cave bears. There is compelling evidence for human hunting of cave bears (Münzel et al. 2011; Wojtal et al. 2015), as well as their competition for caves as a shelter (Grayson and Delpech 2003). Possibly, also large carnivores like cave lion (Panthera spelaea) and cave hyena (Crocuta crocuta spelaea) hunted cave bears while these were hibernating (Bocherens et al. 2011a; Diedrich 2014). The paper reports on, so far, the youngest remains of the cave bear from the Stajnia Cave located in the Częstochowa Upland, Poland. In this region were also found other quite young fossils of this bear in two caves, Komarowa and Deszczowa (Nadachowski et al. 2009; Wojtal 2007; Wojtal et al. 2015). Genetic analyses confirmed beyond doubt the affiliation of this specimen to the cave bear, whereas the direct radiocarbon dating provided the evidence for the survival of this species into the Greenland stadial GS-3. Using this new dating and more than 200 published dates, we estimated the time of cave bear extinction and discussed potential factors of its disappearance and survival in karst regions. *Much more info at site posted.
Amphicyonidae and Hemicyonidae were two early bear-like animals. Amphicyonidae was a group commonly called the "bear dogs." Some members of this group were quite large; Kodiak bear-sized. Although somewhat bear-like is appearance, most experts class them as being more closely related to wolves and dogs. Hemicyonidae were probably closer to the bear family than to dogs even though in size, appearance, and their predatory habits they more closely resembled dogs. They are sometimes referred to as "dog bears."
Both of these unique mammals lived and perished before the appearance of the first true bear. Hemicyonidae existed for about 28 million years and Amphicyonidae for about 44 million years.
http://www.sciencedirect.com/science/article/pii/S1040618213007921
Quaternary International Volumes 339–340, 7 August 2014, Pages 148–163 Fossil remains in karst and their role in reconstructing Quaternary paleoclimate and paleoenvironments Behavioural ecology of Late Pleistocene bears (Ursus spelaeus, Ursus ingressus): Insight from stable isotopes (C, N, O) and tooth microwear Several types of bears lived in Europe during the Late Pleistocene. Some of them, such as cave bears (Ursus s. spelaeus and Ursus ingressus), did not survive after about 25,000 years ago, while others are still extant, such as brown bear (Ursus arctos). Our article aims at a better understanding of the palaeoecology of these large “carnivores” and focuses on two regions, the Ach valley in the Swabian Jura (SW-Germany) with Geißenklösterle and Hohle Fels, and the Totes Gebirge (Austria) with Ramesch and Gamssulzen caves. Both regions revealed two genetically distinct cave bear lineages, and previous studies suggest behavioural differences for the respective bears in these two regions. In the Ach valley, irrespective of the cave site, U. s. spelaeus was replaced by U. ingressus around 28 ka uncal BP with limited chronological overlap without recognizable dietary changes as documented by the isotopic composition (13C, 15N) of the bones. Furthermore, the present study shows that the dental microwear pattern was similar for all bears in both caves, however with a larger variability in Geißenklösterle than in Hohle Fels. In contrast, the two Austrian caves, Gamssulzen (U. ingressus) and Ramesch (Ursus s. eremus), show considerable differences in both palaeodietary indicators, i.e., stable isotopes, and dental microwear, over at least 15,000 years. The oxygen and carbon analysis of the tooth enamel combined with the dental microwear of the same molars provide an extremely diversified picture of the feeding behaviour of these fossil bears. The already known differences between these two study areas are confirmed and refined using the new approaches. Moreover, the differences between the two cave bear lineages in the Totes Gebirge became even larger. Some niche partitioning between both types of cave bears was supported by the present study but it does not seem to be triggered by climate. This multi-disciplinary approach gives new insights into the palaeobiology of extinct bears.
http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_11/Stiner_Vol_11.pdf
CAVE BEAR ECOLOGY AND INTERACTIONS WITH PLEISTOCENE HUMANS ( I will copy and pasted a portion )... SEXUAL SIZE DIMORPHISM IN CAVE BEARS Moder bears exhibit comparatively high levels of size dimorphism between the sexes. Grossly analogous differences in adult stature and weight have been inferred for Pleistocene Ursus species of the northern hemisphere based on the dimensions of canine teeth and weight-bearing limb bones (e.g. Koby 1949; Kurten 1958, 1976). The results on the Yarimburgaz cave bears (Stiner et al. 1998) are based on measurements of carpal or wrist bones (pisiform and scapholunate; Stiner et al. 1998), using Josephson et al.'s (1996) method-of-moments (MoM) technique. This technique assumes that the total distribution of a metric trait is composed of 2 underlying normal distributions, one for males and one for females. Three moments around the mean of the combined-sex distribution are used to estimate the means and the common standard deviation of the 2 underlying distributions. The scale of measurement most easily controlled in paleontological studies is a simple linear one and, to some extent, areal measurements computed therefrom. If the Yarimburgaz size data are extrapolated to yet a third scale of measurement, analogous to body volume or mass, adult male cave bears would have been roughly twice the lean body weight of adult females. This level of sexual size dimorphism is relatively extreme among terrestrial mammals, but not unusual among large-bodied populations of modem brown bears. We infer from this that their mating system was similar to that of extant Ursus species. HOW DID COEXTANT CAVE AND BROWN BEARS DIFFER? Osteometric techniques demonstrate the presence of 2 Middle Pleistocene bear species in the Middle Pleistocene deposits of Yarimburgaz Cave-Ursus (Spelearctos) deningeri, a large cave bear, and U. arctos or brown bear-the former abundant and the latter rare. Acknowledging potential time-averaging effects on fossil assemblages, it nonetheless seems that cave and brown bears coexisted in many areas of Eurasia. Cave bears may have been more prevalent in some regions and periods, possibly at the expense of brown bears, and vice versa. Brown bear teeth from Yarimburgaz Cave are easily distinguished from cave bear teeth on the basis of size. The only brown bear tooth in the M2 sample, for example (Fig. 5), falls well below the maximum (mean) proportional size difference that can be expected between the sexes in any terrestrial mammal (roughly males/females = 1.45-1.50 by a linear standard), even in highly size dimorphic lineages such as bears or the great apes (Pongidae). The other 64 data points form a single cluster (Fig. 5), representing a continuous distribution of male and female cave bear tooth measurements. In addition, an informal comparison of the fifth metacarpals of a mature cave bear and a mature brown bear from Yarimburgaz Cave (Fig. 6) exemplifies dramatic structural differences between the 2 species. The brown bear metacarpal is only somewhat shorter than that of the cave bear, but the difference in robusticity is great. The limb allometry of cave and brown bears also differed. Cave bears possess relatively shorter distal limb elements and longer upper elements than is typical in brown bears (Kurten 1976, Mattson 1998). The cave bear build is interpreted to have emphasized strength over agility or a quick gate, whereas brown bears are relatively fast runners over short distances. Tooth morphology testifies further to differences among brown and cave bears, not least of which were the extraordinary milling capabilities evidenced in the latter. The hyper-developed dental architecture of the cave bear is arguably among the most telling feature in its ecology, as it is expressed by highly conservative elements in the evolution of mammalian skeletons-molar and premolar teeth. The evolutionary effects of limiting similarity are expressed in the bone and dental structures of cave and brown bears. It is interesting in light of this that we cannot distinguish the diets of coextant cave and brown bears in the Yarimburgaz sample on the basis of carbon and oxygen isotope analyses. The isotope data do yield some insights on the diets of cave bears, but these approaches may lack much of the resolution required to differentiate between coextant cave and brown bear diets; perhaps many of the dietary differences exist within the food categories compared by isotope studies (e.g., among C3 plants). In addition to anatomical differences, cave bear hibernation sites tend to be concentrated at relatively high altitudes, thus accounting for their high density in the moder countries of Switzerland and Austria (Rabeder and Nadel In Press). Cave bears were not confined to highlands-their remains also occur in caves at sea level in low frequencies (e.g. Stiner 1994)-but brown bear remains seem to be more common at lower altitudes, as are human archaeological sites dating to before the Upper Paleolithic period.
http://prehistoric-fauna.com/Ursus-maritimus-tyrannus
Ursus maritimus tyrannus is an extinct subspecies of polar bear, known from a single fragmentary ulna found in the gravels of the Thames at Kew Bridge, London. It was named by the Finnish paleontologist Björn Kurtén in 1964 and is interpreted to represent a relatively large subadult individual: the ulna is estimated to have been 48.5 cm long when complete, recent studies only weigh it at 400 kg, for comparison modern subadult polar bear ulnae are 36–43 cm long. Dating back to the Late Pleistocene, approximately 70,000 years ago, it is the oldest fossil assigned to the polar bear; however, an unpublished reinvestigation of the fossil suggests that the fossil is actually a brown bear. Order: Carnivora Family: Ursidae Size: 3,5 m in length, 145 cm in height, 350 - 1000 kg of weight Time period: the Late Pleistocene of Northern Eurasia (70,000 years ago) Typical representative: Ursus maritimus tyrannus Kurtén, 1964 400 kg = 882 pounds.
http://www.polarresearch.net/index.php/polar/article/viewFile/6131/6810
The Kew Bridge find is special in that it is an ulna of a very large animal, considerably larger than present-day polar bears. Kurtén (1964) assigned it to a polar bear subspecies, Ursus maritimus tyrannus. The Kew Bridge specimen has recently been reinvestigated by scientists at London’s Natural History Museum, and they are now confident that the Kew animal was a type of brown bear, U. arctos (Andy Currant, pers. comm. 2008).
After reading posts #181 and #182, was Ursus maritimus tyrannus an early polar bear, an intermediate between the grizzly and the polar bear, or merely a very large grizzly?
  (08-12-2016, 05:56 AM)GrizzlyClaws Wrote:(08-12-2016, 02:03 AM)brotherbear Wrote: Any information about the claws and teeth of Arctodus simus? I'm sure that his claws were not designed for climbing trees. Was he a digger like the grizzly or perhaps his claws were simply dog-like for walking and running. What length canine teeth and claws? (03-04-2017, 02:05 AM)GrizzlyClaws Wrote: @epaiva Yes, it is a Bone Clone fang replica, I have a cave Bear replica too
So both SF bear fang and Cave bear fang measure about 5 inches, but the Cave bear fang was listed as 6 inches by the Bone Clone website, maybe it was an obvious typo.
Art by Ken Doud - California Grizzly meets the short-faced bear, Arctodus simus.
 *This image is copyright of its original author
Skeleton of Short Faced Bear Arctodus simus, it is 3 meters height.
 *This image is copyright of its original author Picture courtesy of William F. Simpson Head Collections of Field Museum of Natural History, Chicago, USA |
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