據(jù)四月份《白堊紀(jì)研究》（Cretaceous Research）報(bào)道，古生物學(xué)家近日發(fā)現(xiàn)了一種在顱骨頂端有壘球大小硬隆起的新恐龍物種,。
這份報(bào)道的主要作者,，來自美國耶魯大學(xué)的尼可拉斯?隆里奇（Nicholas Longrich）介紹說，這種和中等大小的狗差不多體型的素食恐龍生活在7000至8000萬年前,。2008年，這個研究小組就在位于德克薩斯州西南部的大彎曲國家公園（Big Bend National Park）發(fā)現(xiàn)了兩副恐龍的顱骨碎片,。他們把碎片和一些在加拿大和美國蒙大拿州發(fā)現(xiàn)的具有二足和厚顱骨特征的恐龍化石做了比較,，之后他們確定這是一種新腫頭龍,，腫頭龍是一種依靠雙足行走、遲鈍的恐龍,。
研究人員把這個新發(fā)現(xiàn)的恐龍叫做“隆里奇德克薩斯頭龍”（Texacephale langstoni,，“Texacephale”是在特克薩斯發(fā)現(xiàn)的恐龍頭的意思，“langstoni”是為了紀(jì)念古生物學(xué)家Wann Langston所做的貢獻(xiàn)）,。這種恐龍是眾多擁有硬顱骨突起的恐龍物種之一,，隆里奇推測這個隆起是用來出于禮貌撞擊對方的，就像現(xiàn)在的的麝牛和南非水牛一樣,。
這個發(fā)現(xiàn)更加使人確信,，在加拿大和北美洲發(fā)現(xiàn)的恐龍和它們生活在南邊的鄰居截然不同。
這個說法在最近幾年越來越被人們所接受,。“我們發(fā)現(xiàn)很多袖珍恐龍互相之間相當(dāng)孤立,，而不是在美洲大陸隨處走動，”隆里奇說,。“每次我們在德克薩斯州找到新化石,，都發(fā)現(xiàn)它們和北部的不一樣。”
由于在大彎曲國家公園發(fā)現(xiàn)的化石非常珍貴,，卻又沒有受到很好的保護(hù),，科學(xué)家們很難得到關(guān)于這個新恐龍物種的完整圖像。
但是,，研究小組或許已經(jīng)通過這個新發(fā)現(xiàn)揭開了難題的一角,。他們發(fā)現(xiàn)的這個一直以來被認(rèn)為是源于亞洲的恐龍族群，很可能是在來到北美后開始進(jìn)化,。
隆里奇期待在未來得到更多有關(guān)線索,，能在德克薩斯州或其他地方發(fā)現(xiàn)更多化石以供研究。
“我想我低估了這個地方的恐龍種類數(shù)量,，”他說,。
這份報(bào)道的另外兩個作者是來自美國加州州立大學(xué)斯坦尼斯洛斯分校（California State University, Stanislaus）的茱莉亞?薩奇（Julia Sankey）和加拿大皇家泰勒恐龍博物館（Royal Tyrrell Museum）的達(dá)倫?塔克（Darren Tanke）。茱莉亞領(lǐng)導(dǎo)了發(fā)現(xiàn)化石的實(shí)地考察工作,，達(dá)倫則為新恐龍命名找到了更多完整樣本,。（生物谷Bioon.com）
生物谷推薦原文出處：
Cretaceous Research doi:10.1016/j.cretres.2009.12.002
Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA
Nicholas R. Longrich a, Julia Sankey b and Darren Tanke c
a Department of Geology, Yale University, P.O. Box 208109, New Haven, CT 06520-8109, USA
b Department of Physics and Geology, California State University, Stanislaus, One University Circle, Turlock, California 95382, USA
c Royal Tyrrell Museum, P.O. Box 7500, Drumheller, Alberta T0J 0Y0, Canada
Recent work in the Campanian Aguja Formation of Big Bend, Texas, has resulted in the recovery of two frontoparietal domes from a new genus of pachycephalosaur. Texacephale langstoni gen. et sp. nov. is diagnosed by a tall, arched nasal boss, flange-like processes articulating the dome with the peripheral elements, and a low pedicel separating the cerebral fossa from the skull roof. The skull dome is composed largely of the fused frontals and parietals, with limited participation of the peripheral elements, and the supratemporal fenestrae remain open. Phylogenetic analysis indicates that Texacephale langstoni is a basal member of the Pachycephalosauria. The discovery of Texacephale supports previous suggestions that the dinosaur fauna of Texas was distinct from that of contemporary assemblages to the north. The phylogenetic analysis presented here indicates that the Asian pachycephalosaurs form a monophyletic group, deeply nested within the Pachycephalosauridae, and that the basal members of the group are all North American. This finding indicates that pachycephalosaurids originated in North America, rather than Asia, as previously believed. The high diversity of North American pachycephalosaurs and the late appearance of pachycephalosaurs in Asia are consistent with this hypothesis. The biology of Texacephale and other Pachycephalosauridae are also discussed. The morphology of the dome in Texacephale and other pachycephalosaurs supports the hypothesis that pachycephalosaurids engaged in intraspecific combat, while the occurrence of Texacephale and other pachycephalosaurs in nearshore deposits argues that the pachycephalosaurs were not restricted to inland habitats.
