据国外媒体报道，在巴西一个小镇，研究人员发现了距今7000万年的鳄鱼化石，有着狗一样头和巨大的牙齿，被命名为Pissarrachampsa sera。早先由一名市政工人在米纳斯吉拉斯发现，科学家认为在白垩纪这种鳄鱼能够捕食恐龙，回到恐龙时代的末期，这次发现的鳄鱼化石奇怪的头骨让人联想到它应该属于已经灭绝的波罗鳄血统。
研究牵头人，魁北克省麦吉尔大学的Hans Larsson说，尽管现代的两栖鳄鱼有着扁平的头，但是这一新的发现给了我们新的启示：应该去探寻这种已经灭绝的奇怪种群——波罗鳄，它们有着高大的类似于狗一样的骨头和犬齿，四肢较长。它们或许和现代的野狗有某种关系。
根据它们的牙齿的数量和大小，研究者称，这些食肉鳄鱼以15到20英尺的动物为食——而这种体积的动物包括恐龙和同类的一些鳄鱼。它们可能是利用自己立体的视觉去跟踪猎物，而不是像现在的鳄鱼一样去争夺食物，甚至是用细长的四肢跑动追击。一幅由Larsson博士绘制的素描图或许能够显示出这一物种是如何捕食的。
尽管从外形上来看，它们更与恐龙相像而不是现代的鳄鱼，但是头骨化石却能够证明一些那个时代鳄鱼的基本特征。包括拥有发育良好的继发腭、嵌齿、颅骨空间以及粗糙的骨头表面等。
最近，CT扫描揭示了这一化石的一些细节，例如它的大脑大小和规模，听觉能力。波罗鳄有着鲜明的解剖学特点，例如牙齿稀少，向前的鼻孔和衍生的下巴闭合肌肉附件。
通过和以往发现的波罗鳄种类相对比，研究者发现，这一新发现化石在形态上有巨大的差异。研究者试图对这一化石的脑部结构进行数字还原。(生物谷 Bioon.com)
doi:10.1371/journal.pone.0021916
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A New Baurusuchid (Crocodyliformes, Mesoeucrocodylia) from the Late Cretaceous of Brazil and the Phylogeny of Baurusuchidae
Felipe C. Montefeltro, Hans C. E. Larsson, Max C. Langer
Background
Baurusuchidae is a group of extinct Crocodyliformes with peculiar, dog-faced skulls, hypertrophied canines, and terrestrial, cursorial limb morphologies. Their importance for crocodyliform evolution and biogeography is widely recognized, and many new taxa have been recently described. In most phylogenetic analyses of Mesoeucrocodylia, the entire clade is represented only by Baurusuchus pachecoi, and no work has attempted to study the internal relationships of the group or diagnose the clade and its members.
Methodology/Principal Findings
Based on a nearly complete skull and a referred partial skull and lower jaw, we describe a new baurusuchid from the Vale do Rio do Peixe Formation (Bauru Group), Late Cretaceous of Brazil. The taxon is diagnosed by a suite of characters that include: four maxillary teeth, supratemporal fenestra with equally developed medial and anterior rims, four laterally visible quadrate fenestrae, lateral Eustachian foramina larger than medial Eustachian foramen, deep depression on the dorsal surface of pterygoid wing. The new taxon was compared to all other baurusuchids and their internal relationships were examined based on the maximum parsimony analysis of a discrete morphological data matrix.
Conclusion
The monophyly of Baurusuchidae is supported by a large number of unique characters implying an equally large morphological gap between the clade and its immediate outgroups. A complex phylogeny of baurusuchids was recovered. The internal branch pattern suggests two main lineages, one with a relatively broad geographical range between Argentina and Brazil (Pissarrachampsinae), which includes the new taxon, and an endemic clade of the Bauru Group in Brazil (Baurusuchinae).
