The evolution of the old world proboscieeans during the late Neogene.

为了阐明晚第三纪气候变化对东半球鼻目动物进化的影响，1)研究了晚第三纪前鼻目动物(主要是早期大象、刺龙和鼻龙)的系统发育关系；2)研究了这些鼻目动物的食草动物/食草动物习性。肯尼亚纳卡利、埃塞俄比亚中瓦希亚、那空地区早期口鼻虫的新发现。Ratchasima和缅甸证实了剑齿科的单系性，否定了之前认为的剑齿象和早期大象之间的姐妹群关系。在伊洛瓦底群中，发现了从剑齿龙到早期剑齿龙的几乎连续的进化转变。另一方面，Nakali发现了最早的大象样本，这表明它们与四齿象有密切的亲缘关系。晚第三纪的Anancus和Sinomastodon的功能表明，它们中的一些人通过复杂的冠部结构完成了磨牙的觅食功能，有些人在上新世的乞讨下统治了食草动物协会中的早期大象和剑齿象。后来，那些吃草的野象衰落了，大概是被后来的大象打败了，后者通过增加舌象的数量，迅速提高了磨牙水平剪刀的效率。前腭部的下颌运动似乎促进了这种快速的进化。另一方面，剑齿龙在它们的历史上仍然是极端的腕齿，只有在岛屿矮小的形式中可以看到的微小例外。

In order to illuminate the impact of the late Neogene climatic change on the proboscidean evolution in the realm of the Old World 1) the phylogenetic relationship among the late Neogene probosideans, mainly early elephants, stegdons and sinomasotodons and 2) the grazer /browser habit in those proboscideans are investigated. The new finding of the early proboscideans from the Nakali, Kenya, Middle Awash Ethiopia, Nakhon. Ratchasima, and Myanmar, confirmed the monophyly of the Stegodontidae negating previously supposed sister group relationship between stegodons and early elephants. In the Irrawaddy Group, nearly continuous evolutionary transition from the Stegolophodon to early stegodon is recognized. On the other hand, the earliest example of the elephantids are found from Nakali, which suggest close kinship with tetralophoodons.The function of the late Neogene gomphotheres, Anancus and Sinomastodon, suggest some of them accomplished the grazing function of their molars by means of the complication of the crown structure, and some of them dominate the early elephants and stegodonts in the grazer guild at the begging of the Pliocene. Later those grazing gomphotheres are declined, presumably defeated by the later elephants which has rapidly increased the efficiency of the horizontal shearing blade of the molar by means of the increase of the lophid number. Propalinal jaw movements appears to have facilitated such rapid evolution. On the other hand, stegodon remains extreme brachiodonty thorough out their history with the minor exception seen in the island dwarf forms.