Could someone give me the causes of violence and an example of how that happened?

http://www.google.com/search?q=jurassic+period&hl=en&prmd=imvns&source=lnms&ei=fDYPT9yzOcunsQLw_tTLAw&sa=X&oi=mode_link&ct=mode&cd=1&ved=0CDAQ_AUoAA&biw=711&bih=453#sclient=psy-ab&hl=en&source=hp&q=causes+violence&pbx=1&oq=causes+violence&aq=f&aqi=g4&aql=&gs_sm=e&gs_upl=1l4201l1l4384l15l8l0l7l7l0l180l1001l2.5l14l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=202c716ad1e48c82&biw=711&bih=453