Paléobiologie
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REVUE DE VOLUME 34 (1 ) – 2015 PALÉOBIOLOGIE Une institution Ville de Genève www.museum-geneve.ch Revue de Paléobiologie, Genève (juin 2015) 34 (1): 77-84 ISSN 0253-6730 Observations on the Ursus gr. spelaeus remains from the Pocala cave (Trieste, Friuli Venezia Giulia, N. Italy) Mario ROSSI1 & Giuseppe SANTI2 1 Via Sabotino 5, I-37127 Verona, Italy. E-mail: mario.rush@tiscali.it 2 Dipartimento di Scienze della Terra e dell’Ambiente, Via Ferrata 1, I-27100 Pavia, Italy. E-mail: gsanti@unipv.it Abstract 4 Using the fossils of skulls, P /4, M1 stored in the Geological and Paleontological Museum of the University of Padua (Veneto region), the most modern considerations on cave bear remains from the Pocala cave (Friuli Venezia Giulia region), are advanced. These bears belong to the U. spelaeus Rosenmüller, 1794 species and both the morphological-morphometrical and the morphodynamic characters, seem to be intermediate between those typical of the ancestral forms observed in the “deningeri” bears, and the more modern forms of “ingressus”, as in the other Italian populations recently examined (Covoli di Velo, San Donà di Lamon – Veneto region – and Buco del Frate – Lombardy). Keywords Ursus, Pocala, evolution, Eastern Italy, Pleistocene. 1. INTRODUCTION Rosenmüller, 1794 (Lazzaro, 2003) and subsequently as U. eremus Rabeder et al., 2004 (Calligaris et al., 2006). In the last decade the phylogenetic tree of the cave bear Based on fossils stored in the Geological and has changed deeply, and has been complicated as a Paleontological Museum of the University of Padua consequence of the great amount of new data, especially (Veneto region), the object of our study is to improve in the field of genetics (Hänni et al., 1994; Hofreiter et the knowledge about this population of bears, in order to al., 2002, 2007; Orlando et al., 2002; Knapp et al., 2009; better place them in the evolutionary frame of the Italian Stiller et al., 2010; Baca et al., 2012, 2013) and of the and foreign cave bears. evidence of new discoveries. Since then, the distribution of the cave bear has been extended toward the east to Korea and to Western Siberia as well (Baryshnikov, 2. THE POCALA CAVE 2007; Sher et al., 2011). The most important problems concern the taxonomical The hole of the Pocala (cadastral n. 173/91VG of the Friuli place occupied by some ancestral forms (U. rossicus, Venezia Giulia Region) is surely one of the most famous U. savini, U. deningeri and U. kudarensis) including the caves not only of the Friuli Venezia Giulia region, but possibility that cave bear evolution could be characterized in Europe (Fig. 1A). A great amount of cave bear fossils by a premature division into distinct phylogenetic were discovered at this site during numerous excavations lines. Despite the different interpretation given for the that occurred during the 20th century (Calligaris, 2000; morphological, morphometric and genetic data (such as Lazzaro & Tremul, 2003). Initially Battaglia (1930) intraspecific variability or evidence of a specific division), conducted a detailed search, but then the cave was the great polytypism that globally characterizes the cave abandoned for about 70 years (Lazzaro & Tremul, 2003). bear in both its stratigraphic and geographic significance More recently, Lazzaro & Tremul (2003) provided a has become very clear. detailed description of the cave: the hole is located to the The Pocala population is here re-assessed within this NNW of the Aurisina village (Trieste), its entry opens frame. at 139 m. a.s.l. and it consists of a cavity of 6.5 m in The Pocala bear was the object of previous research width and 2 m height. Debris have certainly blocked (Lazzaro, 2003; Rabeder, 2006 in Calligaris et al., and filled a part of the original area. A corridor of about 2006); initially this bear was classified asUrsus spelaeus 65 m long widens underneath to reach 27 m of width Submitted February 2014, accepted 2015 Editorial handling: J.-C. Castel DOI : 10.5281/zenodo.18901 78 M. ROSSI & G. SANTI Fig. 1: Geographical position (A), a summary stratigraphy of the Pocala cave (B) (after Lazzaro & Tremul, 2003, mod.) and map of the cave (C) (GSSG in: www.gssg.it/wp-content/upload/download/2012/09/pianta-caverna-Pocalajpg, slightly modified). Ursus from the Pocala cave 79 at its extremity. The hole ends with a very large room, 45 m long, 50 m wide and 15 high. Marchesetti (1907) published a synthetic stratigraphy recently redrawn by Calligaris (2000, in: Lazzaro & Tremul, 2003) (Fig. 1B). A detailed map of the cave was recently elaborated by the GSSG (Gruppo Speleologico San Giusto - Trieste) (Fig. 1C). 3. MATERIAL AND METHODS Fig. 2: Comparison of the “Basal Length” in skulls of cave 10 skulls, 9 of which are stored into the Geological and bears from the Pocala (n. 10 specimens) and U. spelaeus Paleontological Museum of the University of Padua and from foreign caves. 1 which is preserved in the Museo di Storia Naturale 4 of Milan, 28 P4, 38 P and 21 M1 compose the samples under study. The parameters of the measurements of the skulls and teeth are those codified by Torres (1988a, b, 4 c, d), and are presented in Table 1. On the P /4 and M1 a morphodynamic analysis was also elaborated using methods of Rabeder (1999) and Grandal d’Anglade & López González (2004). The aim of these analyses is to show the presence of the different morphological types within a studied population. In fact, teeth in the more ancient forms (U. deningeri) were characterized by a very Fig. 3: Comparison of the “Basal Length” in skulls of cave simple chewing surface, bicusps (p4) and tricusps (P4); bears from the Pocala (n. 10 specimens) and U. ingressus successively with the formation of numerous accessorial from foreign caves. cusps and crests, a gradual complication become evident, reaching the maximum complexity in U. ingressus. Both the number and position of these accessorial structures allows for the identification a series of morphotypes; the model that studies their distribution makes it possible to calculate the particular indices (morphodynamic indices) indicative of the evolutionary level of the population. The same is true for M1 as well. For this tooth Grandal d’Anglade & López González (2004) have shown a decrease of the degree of convergence of the cusps from Fig. 4: Comparison of the “Basal Length” in skulls of cave the forms of the Lower Pleistocene to those of the Upper bears from the Pocala (n. 10 specimens) and U. ingres- Pleistocene. The degree of convergence is evaluated sus – U. eremus from Conturines and Ramesch caves. using certain indices: 1) the trigonid convergence index and 2) talonid convergence index. The graph in Figure 5 shows the relationship between the “Basal lenght” and the “Maximum frontal Width” of the 4. MORPHOMETRY skulls of different cave bears species. The points corre- sponding to the Pocala population are placed within the In Figures 2-3 the comparisons between the “Basal range of values of both the U. spelaeus and U. ingressus l enght” of the Pocala population and those of some Euro- species. However, contrarily to these species which con- pean cave bears (U. spelaeus and U. ingressus) are shown. tain specimens of small and larger sizes, the Pocala popu- In another comparison between the Pocala fossils and lation is characterized by peculiar proportions. In fact, bears from the Conturines and Ramesch caves (Fig. 4) we the values of the basal length are similar to those of the can note that the Pocala population is characterized by individuals with a great size with respect to the popula- larger sizes compared to the populations of these two tions referred to and the values of the maximum frontal caves which were inhabited by the species U. ladinicus width decreases faster than in both the U. spe laeus and and U. eremus. The range in size of the Pocala population U. ingressus populations, as can be seen by the regres- is similar to those of typically advanced cave bears and, sion line. more in particular, of both U. spelaeus and U. ingressus. The relationship between the “Basal length” and the The analysis of the absolute length and the length of the “Bizygomatic Width” is shown in Figure 6. Also in this dental row has also reached similar conclusions. case the cloud of the Pocala population falls inside the 80 M. ROSSI & G. SANTI Fig. 5: Relationship between the “Basal Length-Maximum Fig. 7: Relationship between the “Basal Length-Maximum frontal Width” in bears from the Pocala and both the U. occipital Width” in bears from the Pocala and both the ingressus and U. spelaeus. U. ingressus and U. spelaeus. Fig. 6: Relationship between the “Basal Length-Bizygomatic Fig. 8: Relationship between the “Basal Length-Length of Width” in bears from the Pocala and both the dental row” in bears from the Pocala and both the U. ingressus and U. spelaeus. U. ingressus and U. spelaeus. range of the referred populations, but the bizygomatic 5. MORPHODYNAMIC DATA width is always proportionally inferior than that observed for both U. spelaeus and U. ingressus species, as the The graphic in Figure 9 shows the relationship between regression lines show. 4 the P /4 morphodynamic index. The point of the Pocala Figure 7 shows the “Basal Length” against the “Maxi- bears falls next to those of both the Conturines (in which mum occipital Width”. In this case the basal length is also the U. ladinicus holotype is present) and the layers contai- proportionally longer for the Pocala population, but the ning U. eremus of the Herdengelh cave. The values of the difference with the U. ingressus species, is very strong.