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

新近纪晚期旧世界长鼻动物的进化。

• 批准号: 17540445
• 负责人: SAEGUSA Haruo
• 金额: $ 2.37万
• 依托单位: University of Hyogo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17540445/
• 关键词: Late Miocene; Proboscidea; phylogeny; masticaiton; elephantidae; Anancus; Steeodon; Sinomastodon; 中新世; 分類学; テトラフォドン類; ゴンフォテリウム類; 骨格; タイ; 咬耗面; 機能形態; テトラロフォドン類; ケニア:エチオピア:タイ

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.

为了阐明新近纪晚期气候变化对旧大陆拟吻动物进化的影响，研究了新近纪晚期拟吻动物（主要是早期大象、剑齿兽和中剑齿兽）的系统发育关系，以及这些拟吻动物的食食习性。新发现的来自Nakali， Kenya, Middle Awash, Ethiopia， Nakhon的早期长鼻目动物。Ratchasima和Myanmar证实了剑齿虎科的单系性，否定了之前假设的剑齿虎和早期大象之间的姐妹群关系。在伊洛瓦底群中，从剑龙到早期剑龙的进化过渡几乎是连续的。另一方面，最早的象类是在Nakali发现的，这表明它们与四爪象有着密切的亲缘关系。新近世晚期象鼻兽Anancus和Sinomastodon的功能表明，它们中的一些通过冠状结构的复杂性完成了磨牙的放牧功能，而另一些则在上新世乞讨时主导了早期大象和剑齿兽的食草行会。后来，这些食草类象类逐渐减少，大概是被后来的大象打败了。后来的大象通过象类数量的增加，迅速提高了臼齿水平剪切刃的效率。前腭部的运动似乎促进了如此快速的进化。另一方面，剑齿虎在它们的整个历史中都保持着极端的腕齿性，只有岛上侏儒兽例外。

项目成果

Neogene mammalian fauna in Myanmar

• 发表时间: 2006
• 作者: M. Takai;H. Saegusa;Thaung-Htike;Zin-Maung-Maung-Thein-Zin-Maung-Maung-Thein-1402677736

Preliminary investigations on the Neogene proboscideans from Myanmar

缅甸新近纪长鼻动物的初步调查

• 发表时间: 2006
• 作者: Saegusa;H.;Thaung-Htike;Zin-Maung-Maung-Thein;Takai;M.;Chit Sein
• 通讯作者: Chit Sein

Earliest elephantid remains from Nakali, Kenya

肯尼亚纳卡利最早的大象遗骸

• 发表时间: 2006
• 作者: Saegusa;H.;Nakaya;H.;Kunimatsu;Y.;Nakatsukasa;M.;Tsujikawa;H
• 通讯作者: H

Jaw movement and the wear facets of proboscideans

长鼻动物的下颌运动和磨损面

• 发表时间: 2005
• 作者: Saegusa;H
• 通讯作者: H

The paleoecology an paleogeographic conteXt of Lemudong'o,Locality 1,a late Miocene terrestrial fossil site in southern Kenya

肯尼亚南部中新世晚期陆地化石遗址 1 号地点 Lemudongo 的古生态学和古地理环境

• 发表时间: 2007
• 期刊: Kirtlandia 56
• 作者: Ambrose;H.S.;et. al.
• 通讯作者: et. al.