Etruscan and Cave Bears
    Another branch of U. minimus gave rise to U. etruscus, which first appeared during the mid-Villafranchian   (Fig. 4:4).  Remains have been found from Europe to China.  The skeleton of Etruscus was initially similar is size, as well as structure, to that of a modern Asian black bear.  But Etruscus eventually reached the size of a modern European brown bear by the end of the Villafranchian (Tiglian interglacial) before extinction (Kurte'n 1976, Kurte'n & Anderson 1980).  Etruscus retained all its premolars although they were very small; the anterior ones were little more than useless pegs.  The carnassials were also reduced.
 
Figure 4:4. Skulls of Cave Bears
 
 
    Meanwhile, one of the Etruscan bear's branch species survived through the Donau glacial and Waalian interglacial, giving rise to a yet larger animal, U. savini.  If Savin's bear retained any premolars except the most posterior, they were vestigial.  Its forehead was slightly domed, foreshadowing the high doming of its descendants, the larger-bodied "true" cave bears.  Remains have been found in England and Austria.  Later, during one of the warm interludes of the Gunz glaciation, a longer-legged variety of Savin's bear briefly invaded Europe.  (Kurte'n 1976).
    The earliest true cave bear, the so-called "Deninger's" species (U. deningeri) is found in deposits from the Cromerian interglacial and Mindel glacial.  This was larger than Savin's bear, with more doming of the forehead, a longer jaw, and expanded grinding teeth.  (Kurte'n 1976).    
  By the Mindel glaciation, or at least the Holsteinian interglacial, the full-fledged cave bear U. spelaeus occupied central Europe.  This species had a more domed skull and larger molars than most other bears, but comparable to those of a panda bear.  Both traits are adaptations to a predominantly herbivorous diet.  (Kurte'n 1976).    Spelaeus was abundant during the interstadial Wurm I-II, about 30,000 YA.  But by the close of the Wurm, in the Magdelenian, only remnant populations remained; even these were gone by the end of the Magdalenian (Kurten 1968).
    Kurte'n's (1976) description of the morphology of the North American spectacled bear was quoted earlier--traits evolved in the mild climate of the Gulf Coast.  Yet, the European cave bear, which evolved in peri-glacial conditions, shares those same basic morphological traits.  Apparently, they were adaptations not to a particular climatic regime, but to chewing tough plants and to a dependence for protection from enemies on great size and strength--perhaps related to foraging away from readily climbable trees (see Herrero 1972, 1978; Kurte'n 1976).  Aside from this convergence, the Tremarctinae and Ursinae are quite different.  
  In general, European cave bears were confined between latitudes of 38 to 51oN (which also approximates the prehistoric northerly range limit for Asian black bears), within about 600 km of the coast (Atlantic, Mediterranean, or Black Sea).  This range includes southern England and continental Europe from Belgium down to northern Spain, Italy, and the Balkans north of Greece, and as far east as Odessa and the Caucasus.  Cave bears may have reached North Africa and Palestine too   (Fig. 2:9); but they apparently never invaded Asia.  (Kurte'n 1976).  
 
Figure 4:5. Distributions of European Cave Bears and of Major Limestone Cave Regions in Cave Bear Range
 
 
Figure 4.2. Distributions of European cave bear  fossils and of limestone caves of the types used by these bears..  Distribution of cave bear is based on fossils (Kurten 1976: Fig. 22).  Most fossils have been found in limestone caves.  Major concentrations of limestone caves in that region are mapped (after Sweeting 1973).  Scattered cave sites are not mapped, which might explain why distribution of cave bears is wider than that of major cave concentrations.  Cave bears may have never thrived outside of areas with caves for hibernation.  Of course, not all areas with caves also met their other needs.  Some may have been too arid.
 
 
    Geographic distribution of cave bears may have been limited by climatic effects on food supply.  During the Weichselian and possibly other Pleistocene glaciations    (Table 2:1) most cave bear range was covered with tundra; forest was confined mainly to coastal areas. By contrast, during interglacials, most of their range was covered with forest, interspersed with wetlands and meadows--as is currently true. (Kurte'n 1976).  
    Another factor limiting their distribution may have been the availability of caves.  Kurte'n (1976) notes that remains are almost always found associated with caves or in region where caves occur.  Apparently these caves are mainly caverns in limestone or other rock that is readily dissolved or eroded    (Fig. 4:2).
 
Figure 4:6. Cave Bear Mandibles & Skulls
 
 
                    Mandible, Specimen 1                                                  Mandible, Specimen 2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                       Mandible, Specimen 3                                                  Mandible, Specimen 4
 
 
 
 
 
                        
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Skull with mandible,
Specimen 5
 
 
 
Skull, Specimen 6   with full mandible of Specimen 7, a much larger bear.
Multiple views
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                       Cave Bear specimen 8
 
 
 
 
 
 
 
 
 
 
 
 
                                                                                                                          Cave Bear specimen 9
 
 
 
Cave Bear specimen 10
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 4:7. Cave Bear vs. Giant Short-Faced Bear
 
 
Compare the cave bear above and at left, with the  Giant Short-Faced bears shown below. (The skull of
each specimen was scaled to the same length so that differences in relative size are clear.)  The cave bear had a higher skull, longer muzzle, shorter legs, and probably a much slower gait.  It was better adapted for digging and eating tough vegetation.   (The full Arctodus skeletons are replicas produced by Bone Clones boneclones.com.)  Skeletal differences are even more apparent in the drawings that follow -- expanding upon Fig. 3:2.
                                                                                      
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Skeletons of Tremarctinae vs. Ursinae
 
 
This diagram is most useful for comparison of general body proportions and relative body size among genera.  (Tremarctos from Kurte’n 1966.  Arctodus from Emslie & Czaplewski 1985; skeleton partially reconstructed by the authors.  U. spelaeus from Kurte’n 1976; U. arctos from Lydeckker 1934)
 
 
 
 
Chapter 4. URSINAE (cont.) >>
                   Ch. 4a:  Ancestral Ursinae & Modern Black Black Bears  
                   Ch. 4c:  Modern Grizzly/Brown, Polar, Sun & South Bears
 
Chapter 4.  URSINAE (b)